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Inconsistencies have been reported on the effect of sex on aldosterone (ALDO) levels leading to clinical confusion. The reasons for these inconsistencies are uncertain but include estrogen and/or its receptor modulating target gene responses to mineralocorticoid receptor activation and ALDO secretagogues’ levels. This study’s goal was to determine whether ALDO’s biosynthesis also differed by sex. Two approaches were used. First, plasma renin activity and aldosterone were measured in rats. Both were significantly higher in males. Secondly, using rat zona glomerulosa (ZG) cells, we assessed three ex vivo areas: (1) activity/levels of early steps in ALDO’s biosynthesis (StAR and CYP11A1); (2) activity/levels of a late step (CYP11B2); and (3) the status of the mineralocorticoid receptor (MR)-mediated, ultrashort feedback loop. Females had higher expression of CYP11A1 and StAR and increased CYP11A1 activity (increased pregnenolone/corticosterone levels) but did not differ in CYP11B2 expression or activity (ALDO levels). Activating the ZG’s MR (thereby activating the ultrashort feedback loop) reduced CYP11B2’s activity similarly in both sexes. Exvivo, these molecular effects were accompanied, in females, by lower ALDO basally but higher ALDO with angiotensin II stimulation. In conclusion, we documented that not only was there a sex-mediated difference in the activity of ALDO’s biosynthesis but also these differences at the molecular level help explain the variable reports on ALDO’s circulating levels. Basally, both in vivo and ex vivo, males had higher ALDO levels, likely secondary to higher ALDO secretagogue levels. However, in response to acute stimulation, ALDO levels are higher in females because of the greater levels and/or activity of their StAR/CYP11A1.

Growth Hormone-Releasing Peptide 6 (GHRP-6) (His-(D-Trp)-Ala-Trp-(D-Phe)-Lys-NH2) is an agonist of the growth hormone secretagogue receptor. GHRP-6 mimics the effect of ghrelin. The present study focuses on the immunomodulatory effects of GHRP-6 in tilapia with and without the presence of Pseudomonas aeruginosa infection. GHRP-6 up-regulated the transcription levels of three piscidin-like antimicrobial peptides (Oreochromicins I, II, and III) and granzyme in a tissue-dependent manner. Antimicrobial activity stimulation in serum (lysozyme and anti-protease activity) was also confirmed. Besides, GHRP-6 enhanced the in vitro antimicrobial activity against P. aeruginosa in tilapia gills mucus and serum samples and decreased the bacterial load in vivo after infection with this Gram-negative bacterium. Our results evidenced, for the first time, a direct link between a growth hormone secretagogue ghrelin mimetic in fish and the enhancement of antimicrobial peptides transcription, which suggests that this secretagogue is capable to lead the activation of microbicidal activity in tilapia. Thus, these results open new possibilities for GHRP-6 application in aquaculture to stimulate the teleost immune system as an alternative treatment against opportunistic bacteria.

Coptis chinensis is an ancient Chinese herb treating diabetes in China for thousands of years. However, its underlying mechanism remains poorly understood. Here, we report the effects of its main active component, berberine (BBR), on stimulating insulin secretion. In mice with hyperglycemia induced by a high-fat diet, BBR significantly increases insulin secretion and reduced blood glucose levels. However, in mice with hyperglycemia induced by global or pancreatic islet β-cell-specific Kcnh6 knockout, BBR does not exert beneficial effects. BBR directly binds KCNH6 potassium channels, significantly accelerates channel closure, and subsequently reduces KCNH6 currents. Consequently, blocking KCNH6 currents prolongs high glucose-dependent cell membrane depolarization and increases insulin secretion. Finally, to assess the effect of BBR on insulin secretion in humans, a randomized, double-blind, placebo-controlled, two-period crossover, single-dose, phase 1 clinical trial (NCT03972215) including 15 healthy men receiving a 160-min hyperglycemic clamp experiment is performed. The pre-specified primary outcomes are assessment of the differences of serum insulin and C-peptide levels between BBR and placebo treatment groups during the hyperglycemic clamp study. BBR significantly promotes insulin secretion under hyperglycemic state comparing with placebo treatment, while does not affect basal insulin secretion in humans. All subjects tolerate BBR well, and we observe no side effects in the 14-day follow up period. In this study, we identify BBR as a glucose-dependent insulin secretagogue for treating diabetes without causing hypoglycemia that targets KCNH6 channels., Berberine is a compound with glucose-lowering effects in mice and humans. Here, the authors show that in mice berberine has beneficial glycemic effects by promoting insulin secretion, which requires the potassium channel KCNH6 in beta cells, and that berberine can promote insulin secretion in healthy men in a phase 1 clinical trial.

In the present study, we investigated the hypoglycemic effect of different extracts (i.e. organic and aqueous) derived from the fruits of Hyphaene thebaica (doum) on male streptozotocin-induced diabetic rats. Blood glucose levels as well as the relative gene expression of insulin, TNF-α, and TGF-β were determined in the pancreatic tissue of the experimental animals. Treatment of STZ-induced diabetic rats with aqueous extracts of the plant fruit over 7 weeks significantly reduced the elevated blood glucose and increased the relative expression of insulin, while the relative expression of inflammatory mediators (i.e. TNF-α and TGF-β) was significantly reduced. Histopathological investigation also revealed that the aqueous extract treatment effectively reversed the β-cell necrosis induced by STZ and restored its normal morphology. Furthermore, liquid chromatography high resolution mass spectrometry (LC-HRMS) and in silico chemical investigation of the aqueous extract elucidated its major bioactive phytochemicals (i.e. flavonoids) and putatively determined the pancreatic KATP channel as a target for these bioactive components. In vitro insulin secretion assay revealed that myricetin, luteolin, and apigenin were able to induce insulin secretion by human pancreatic cells (insulin production = 20.9 ± 1.3, 13.74 ± 1.8, and 11.33 ± 1.1 ng mL-1, respectively). Using molecular docking and dynamics simulations, we were able to shed the light on the insulin secretagogue's mode of action through these identified bioactive compounds and to determine the main structural elements required for its bioactivity. This comprehensive investigation of this native fruit will encourage future clinical studies to recommend edible and widely available fruits like doum to be a part of DM treatment plans.

The intestines have been recognized as important tissues for metabolic regulation, including glycemic control, but their vital role in promoting the anti-diabetic effects of bitter melon, the fruit of Momordica charantia L, has seldom been characterized, nor acknowledged. Evidence suggests that bitter melon constituents can have substantial interactions with the intestinal epithelial cells before circulating to other tissues. We therefore characterized the effects of bitter melon extract (BME) on intestinal epithelial cells. BME was found to contain substantial amounts of carbohydrates, proteins, and triterpenoids. TNF-α induced insulin resistance in an enterocyte cell line of IEC-18 cells, and BME promoted glucose utilization of the insulin-resistant cells. Further analysis suggested that the increased glucose consumption was a result of the combined effects of insulin sensitizing and insulin substitution functions of BME. The functions of insulin substitution were likely generated due to the activation of AMP-activated protein kinase. Meanwhile, BME acted as a glucagon-like peptide 1 (GLP-1) secretagogue on enteroendocrine cells, which may be mediated by the activation of bitter-taste receptors. Therefore, BME possesses insulin sensitizing, insulin substitution, and GLP-1 secretagogue functions upon intestinal cells. These effects of BME on intestinal cells likely play a significant part in the anti-diabetic action of bitter melon.

Ghrelin - a growth hormone (GH) secretagogue - presents a circadian rhythm with higher nocturnal than diurnal concentration (similar to GH). However, daily ghrelin production depends on food intake and nutritional state; it is increased in the fasting state and decreased after a meal. Since most past research concerning short stature children has relied on the morning ghrelin concentration for analyses, we decided to assess ghrelin concentration at the 60

Goals To assess short-term and long-term effects of lubiprostone, a type-2 chloride channel activator, on electrolyte homeostasis. Background Conventional laxatives are associated with electrolyte imbalances. Lubiprostone is a type-2 chloride channel activator approved for treating chronic idiopathic constipation (CIC), opioid-induced constipation (OIC), and constipation-predominant irritable bowel syndrome in women. It induces intestinal fluid secretion, possibly affecting water and electrolyte homeostasis. We investigated short-term and long-term effects of lubiprostone on electrolyte, blood urea nitrogen (BUN), and creatinine levels using pooled data from CIC and OIC patients. Study Data were pooled from 10 CIC and OIC studies-6 double-blind, randomized, placebo-controlled studies and 4 open-label, long-term studies. Total duration of lubiprostone exposure was from 3 weeks (short-term: CIC, 3 to 4 wk; OIC, placebo-controlled, 12 wk) to 48 weeks (long-term: CIC, 24 to 48 wk; OIC, 48 wk). Sodium, chloride, potassium, magnesium, BUN, and creatinine levels were examined at baseline and final assessment. Results Overall, 3209 patients were assessed. In the double-blind, placebo-controlled studies, there were no clinically meaningful differences in levels of electrolytes, BUN, and creatinine between lubiprostone and placebo groups, and in changes from baseline levels with long-term use of lubiprostone. Analyses of shifts in laboratory values (low/normal/high) at baseline and final assessment showed minimal effects on electrolytes, BUN, and creatinine. Conclusions Lubiprostone did not cause clinically meaningful electrolyte imbalances or affect markers of renal function in either the short-term or long-term treatment of CIC or OIC.

Circulating growth hormone (GH) concentrations increase during pregnancy in mice and remain pituitary-derived. Whether abundance or activation of the GH secretagogue ghrelin increase during pregnancy, or in response to dietary octanoic acid supplementation, is unclear. We therefore measured circulating GH profiles in late pregnant C57BL/6J mice and in aged-matched non-pregnant females fed with standard laboratory chow supplemented with 5% octanoic or palmitic (control) acid (n = 4–13/group). Serum total and acyl-ghrelin concentrations, stomach and placenta ghrelin mRNA and protein expression, Pcsk1 (encoding prohormone convertase 1/3) and Mboat4 (membrane bound O-acyl transferase 4) mRNA were determined at zeitgeber (ZT) 13 and ZT23. Total and basal GH secretion were higher in late pregnant than non-pregnant mice (P P = 0.004), but not acyl-ghrelin, and the density of ghrelin-positive cells in the gastric antrum (P = 0.019) were higher, and gastric Mboat4 and Pcsk1 mRNA expression were lower in pregnant than non-pregnant mice at ZT23. In the placenta, ghrelin protein was localised mostly to labyrinthine trophoblast cells. Serum acyl-, but not total, ghrelin was lower at mid-pregnancy than in non-pregnant mice, but not different at early or late pregnancy. In conclusion, dietary supplementation with 5% octanoic acid did not increase activation of ghrelin in female mice. Our results further suggest that increases in maternal GH secretion throughout murine pregnancy are not due to circulating acyl-ghrelin acting at the pituitary. Nevertheless, time-dependent increased circulating total ghrelin could potentially increase ghrelin action in tissues that express the acylating enzyme and receptor.

Objectives The aim of this study is to investigate the phytochemical and the long-term anti-neuropathic potentials of Crocus sativus cultivated in the University botanical garden, and explore its most bioactive compounds and their underlying mechanisms of action. Methods Phytochemical analysis and bio-guided isolation-procedures including RP-HPLC and 1H and 13C NMR utilizing biological models of diabetes, inflammation, and diabetic-neuropathy were used. Cultivated saffron (S-RCED) and Spanish-saffron stigma (S-SP) alone or in combination with Camellia sinus (CS) were investigated. Results The RP-HPLC analyses showed the presence of picrocrocin, crocin I, crocin II, crocin I’, crocin II’, and safranal (SAF) in both S-SP and S-RCED extracts with higher-concentrations. It had been shown that SAF was the most bioactive-compound in Crocus sativus. Both S-SP and S-RCED possessed significant (P Conclusion The oxidative stress reduction, insulin secretagogue, and pancreatic beta-cells regeneration potentials might be responsible for the mechanism underlying the anti-diabetic, anti-inflammatory and anti-diabetic neuropathy activities. Thus, the cultivated Crocus sativus might be clinically useful for protecting against many serious-disorders.

SummaryThe mammalian circadian clock drives daily oscillations in physiology and behavior through an autoregulatory transcription feedback loop present in central and peripheral cells. Ablation of the core clock within the endocrine pancreas of adult animals impairs the transcription and splicing of genes involved in hormone exocytosis and causes hypoinsulinemic diabetes. However, identification of druggable proteins and pathways to ameliorate the burden of circadian metabolic disease remains a challenge. Here, we generated β cells expressing a nano-luciferase reporter within the proinsulin polypeptide to screen 2,640 pharmacologically-active compounds and identify insulinotropic molecules that bypass the secretory defect in clock mutant β cells. We validated lead compounds in primary mouse islets and identified known modulators of ligandgated ion channels and G-protein coupled receptors, including the antihelmintic ivermectin. Single-cell electrophysiology in circadian mutant mouse and human cadaveric islets validated ivermectin as a glucose-dependent secretagogue. Genetic, genomic, and pharmacologic analyses established that the molecular clock controls the expression of the purinergic P2Y1 receptor to mediate the insulinotropic activity of ivermectin. These findings identify the P2Y1 purinergic receptor as a target to rescue circadian β-cell failure and establish a chemical genetic screen for endocrine therapeutics.

(1) Background: Artemia salina is a brine shrimp containing high concentrations of dinucleotides, molecules with properties for dry eye treatment. For this reason, the purpose of the study was to evaluate the effect of the artificial tears based on an extract of Artemia salina in a rabbit dry eye model. (2) Methods: A prospective and randomized study was carried out. Twenty rabbits were divided into 4 groups (n = 5, each group): healthy rabbits, dry eye rabbits, dry eye rabbits treated with hypromellose (HPMC), and dry eye rabbits treated with Artemia salina. Dry eye was induced by the topical instillation of 0.2% benzalkonium chloride. The measurements were performed before and after the treatment for 5 consecutive days. (3) Results: The topical instillation of artificial tears containing Artemia salina showed beneficial effects on tear secretion, tear break-up time, corneal staining, the density of Goblet cells, heigh of mucin cloud secreted by these cells, and mRNA levels of IL-1β and MMP9 in conjunctival cells. Compared with the HPMC, there was a statistically significant improvement (p &lt, 0.05) with the Artemia salina in all the variables under study, except for the conjunctival hyperemia, density of Goblet cells, and mRNA levels of IL-6. (4) Conclusions: The potential of artificial tears based on Artemia salina as a secretagogue agent for dry eye treatment was confirmed, opening the door for future clinical trials and studies to extrapolate the findings for dry eye patients.

In this article the author name Tetsuro Izumi was incorrectly written as Testuro Izumi. The original article has been corrected.

Background and aim: Angiotensin II type 1 (AT1) receptor blockers (ARBs), as antihypertensive drugs, have drawn attention for their benefits to individuals with diabetes and prediabetes. However, the direct effects of ARBs on insulin secretion remain unclear. In this study, we aimed to investigate the insulinotropic effect of ARBs and the underlying electrophysiological mechanism. Methods: Islets isolated from Wistar rats or db/db mice were incubated with drugs under different glucose conditions for 30 minutes, then supernatant liquid was collected for insulin secretion. Intracellular Ca2+ ([Ca2+]i) levels of β-cells were measured by calcium imaging technology. Patch-clamp technology was applied to detect effects on action potential duration (APD), Voltage-dependent potassium (Kv) channels, and voltage-gated calcium channels (VGCC). In our in vivo experiment, the 8-week-old and 11-week-old db/db mice were separately administered acute oral acute oral telmisartan treatment (15 mg/kg), then the oral glucose tolerance test (OGTT) was performed to observe the insulinotropic effect of telmisartan at 2 hours following drug intake.Results: Only telmisartan among the three ARBs（telmisartan, valsartan, and irbesartan）exhibited an insulin secretagogue role in rat islets. Independent of AT1 receptor and peroxisome proliferator-activated receptor γ (PPARγ), telmisartan exerted effects on ion channels including Kv channels and L-type VGCCs to promote extracellular Ca2+ influx, thereby potentiating insulin secretion in a glucose-dependent manner. Furthermore, we identified that telmisartan directly inhibited Kv2.1 channel on a Chinese hamster ovary cell line with Kv2.1 channel overexpression. Acute exposure of db/db mice to a telmisartan dose equivalent to therapeutic doses in humans resulted in lower blood glucose and increased plasma insulin concentration in OGTT. We further observed the telmisartan-induced insulinotropic and electrophysiological effects on pathological pancreatic islets isolated from db/db mice. Conclusions: Our results establish an important insulinotropic function of telmisartan distinct from other ARBs in the treatment of diabetes.

Background The hormone ghrelin is the endogenous agonist of the G-protein coupled receptor (GPCR) termed growth-hormone secretagogue receptor (GHSR). Ghrelin inhibits glucose-stimulated insulin secretion by activating pancreatic GHSR. Recently, Liver-Expressed Antimicrobial Peptide 2 (LEAP2) was recognized as an endogenous GHSR ligand that blocks ghrelin-induced actions. Nonetheless, the effect of LEAP2 on glucose-stimulated insulin secretion from pancreatic islets is unknown. Objectives We aimed at exploring the activity of LEAP2 on glucose-stimulated insulin secretion. Methods Islets of Langerhans isolated from rat pancreas were exposed to glucose in the presence or in the absence of LEAP2 and ghrelin and then insulin secretion was assayed. Results LEAP2 did not modulate glucose-stimulated insulin secretion. However, LEAP2 blocked the insulinostatic action of ghrelin. Conclusion Our data show that LEAP2 behaves as an antagonist of pancreatic GHSR.

The pancreatic beta-cell transduces the availability of nutrients into the secretion of insulin. While this process is extensively modified by hormones and neurotransmitters, it is the availability of nutrients, above all glucose, which sets the process of insulin synthesis and secretion in motion. The central role of the mitochondria in this process was identified decades ago, but how changes in mitochondrial activity are coupled to the exocytosis of insulin granules is still incompletely understood. The identification of ATP-sensitive K+-channels provided the link between the level of adenine nucleotides and the electrical activity of the beta cell, but the depolarization-induced Ca2+-influx into the beta cells, although necessary for stimulated secretion, is not sufficient to generate the secretion pattern as produced by glucose and other nutrient secretagogues. The metabolic amplification of insulin secretion is thus the sequence of events that enables the secretory response to a nutrient secretagogue to exceed the secretory response to a purely depolarizing stimulus and is thus of prime importance. Since the cataplerotic export of mitochondrial metabolites is involved in this signaling, an orienting overview on the topic of nutrient secretagogues beyond glucose is included. Their judicious use may help to define better the nature of the signals and their mechanism of action.

Background Glucose-dependent insulinotropic polypeptide (GIP) has been suggested to stimulate the secretion of pancreatic polypeptide (PP), an islet hormone thought to regulate gut motility, appetite, and glycemia. Objective To determine whether human GIP1-42 (hGIP) stimulates PP secretion. Method As glycemia modulates the secretion of PP, we measured plasma PP concentrations from 2 studies in healthy men (n = 10) and in patients with type 2 diabetes (T2D) (n = 12), where hGIP1-42 had been administered intravenously during fasting glycemia, hyperglycemia (12 mmol/L), and insulin-induced hypoglycemia (targets: 2.5 mmol/L [healthy]; 3.5 mmol/L [T2D]). Porcine GIP1-42 (pGIP) was also infused intra-arterially in isolated porcine pancreata (n = 4). Results Mean fasting plasma glucose concentrations were approximately 5 mmol/L (healthy) and approximately 8 mmol/L (T2D). At fasting glycemia, PP concentrations were higher during intravenous hGIP1-42 infusion compared with saline in healthy men (mean [standard error of the mean, SEM], net incremental areas under the curves (iAUCs)[0-30min], 403 [116] vs –6 [57] pmol/L × min; P = 0.004) and in patients with T2D (905 [177] vs –96 [86] pmol/L × min; P = 0.009). During hyperglycemic clamping, mean [SEM] PP concentrations were significantly higher during hGIP1-42 infusion compared with saline in patients with T2D (771 [160] vs –183 [117] pmol/L × min; P = 0.001), but not in healthy individuals (–8 [86] vs –57 [53] pmol/L × min; P = 0.69). When plasma glucose levels were declining in response to exogenous insulin, mean [SEM] PP concentrations were higher during hGIP1-42 infusion compared with saline in healthy individuals (294 [88] vs –82 [53] pmol/L × min; P = 0.0025), but not significantly higher in patients with T2D (586 [314] vs –120 [53]; P = 0.070). At target hypoglycemia, PP levels surged in both groups during both hGIP1-42 and saline infusions. In isolated pancreata, pGIP1-42 increased mean [SEM] PP output in the pancreatic venous effluent (baseline vs infusion, 24[5] vs 79 [16] pmol/min x min; P = 0.044). Conclusion GIP1-42 increases plasma PP secretion in healthy individuals, patients with T2D, and isolated porcine pancreata. Hyperglycemia blunts the stimulatory effect of hGIP1-42 in healthy individuals, but not in patients with T2D.

Genetic susceptibility to type 2 diabetes is primarily due to β cell dysfunction. However, a genetic study to directly interrogate β cell function ex vivo has never been previously performed. We isolated 233,447 islets from 483 Diversity Outbred (DO) mice maintained on a Western-style diet, and measured insulin secretion in response to a variety of secretagogues. Insulin secretion from DO islets ranged greater than 1000-fold even though none of the mice were diabetic. The insulin secretory response to each secretagogue had a unique genetic architecture; some of the loci were specific for one condition, whereas others overlapped. Human loci that are syntenic to many of the insulin secretion quantitative trait loci (QTL) from mice are associated with diabetes-related SNPs in human genome-wide association studies. We report on 3 genes, Ptpn18, Hunk, and Zfp148, where the phenotype predictions from the genetic screen were fulfilled in our studies of transgenic mouse models. These 3 genes encode a nonreceptor type protein tyrosine phosphatase, a serine/threonine protein kinase, and a Krϋppel-type zinc-finger transcription factor, respectively. Our results demonstrate that genetic variation in insulin secretion that can lead to type 2 diabetes is discoverable in nondiabetic individuals.

Astragalin is a flavonol glycoside with several biological activities, including antidiabetic properties. The objective of this study was to investigate the effects of astragalin on glycaemia and insulin secretion, in vivo, and on calcium influx and insulin secretion in isolated rat pancreatic islets, ex vivo. Astragalin (1 and 10 mg / kg) was administered by oral gavage to fasted Wistar rats and serum glucose and plasma insulin were measured. Isolated pancreatic islets were used to measure basal insulin secretion and calcium influx. Astragalin (10 mg/ kg) decreased glycaemia and increased insulin secretion significantly at 15–180 min, respectively, in the glucose tolerance test. In isolated pancreatic cells, astragalin (100 μM) stimulated calcium influx through a mechanism involving ATP-dependent potassium channels, L-type voltage-dependent calcium channels, the sarcoendoplasmic reticulum calcium transport ATPase (SERCA), PKC and PKA. These findings highlight the dietary coadjuvant, astragalin, as a potential insulin secretagogue that may contribute to glucose homeostasis.

Summary: Repaglinide (RPG) is a short-acting insulin secretagogue widely prescribed for the treatment of type 2 diabetes. It boosts insulin secretion by inhibiting the pancreatic ATP-sensitive potassium channel (KATP). However, the mechanisms by which RPG binds to the KATP channel are poorly understood. Here, we describe two cryo-EM structures: the pancreatic KATP channel in complex with inhibitory RPG and adenosine-5’-(γ-thio)-triphosphate (ATPγS) at 3.3 Å and a medium-resolution structure of a RPG-bound mini SUR1 protein in which the N terminus of the inward-rectifying potassium channel 6.1 (Kir6.1) is fused to the ABC transporter module of the sulfonylurea receptor 1 (SUR1). These structures reveal the binding site of RPG in the SUR1 subunit. Furthermore, the high-resolution structure reveals the complex architecture of the ATP binding site, which is formed by both Kir6.2 and SUR1 subunits, and the domain-domain interaction interfaces. : Ding et al. report the detailed binding site and the inhibitory mechanism of the insulin secretagogue repaglinide on the pancreatic KATP channel, revealed by a 3.3 Å cryo-EM structure and electrophysiology experiments. Keywords: diabetes, KATP channel, repaglinide, glibenclamide, sulfonylurea, glinides, Kir, SUR, ABC transporter, KNtp

A potentiating effect of medium-chain triglycerides on glucose-stimulated insulin secretion (GSIS) has been observed since the 1960s. Subsequent observations identified octanoic acid (OA), the main component of medium-chain triglyceride, as the potentiator of GSIS, but the mechanism was unclear. We used wild-type (WT), short-chain 3-hydroxyacyl-CoA dehydrogenase knockout (Hadh(-/-)), and sulfonylurea receptor 1 knockout (Sur1(-/-)) mouse islets to define the mechanism of OA potentiation of insulin secretion. Application of OA alone induced a 2- to 3- fold increase of insulin secretion with an apparent threshold of 3 mM in WT mouse islets, suggesting that OA itself is a weak insulin secretagogue. However, OA at 1 mM strongly potentiated fuel-stimulated insulin secretion, especially GSIS. The potentiating effect on fuel-stimulated insulin secretion by OA did not require fatty acid β-oxidation because OA also potentiated amino acid-stimulated insulin secretion in islets isolated from Hadh(-/-) mice, which cannot fully oxidize OA. Measurements using Sur1(-/-) islets indicated that the potentiating effect of OA on fuel-stimulated insulin secretion is Ca(2+) dependent and is often accompanied by β-cell membrane potential depolarization, and may also involve the Ca(2+)/calmodulin complex. Experiments using DCPIB, an ethacrynic acid derivative, to inhibit volume-sensitive anion channels (VSACs) in Sur1(-/-) islets demonstrated that the potentiation effects of OA on insulin secretion are in part medicated by activation of VSAC. In addition, inhibition of IP3 receptor also abolishes the OA-induced intracellular Ca(2+) increase in Sur1(-/-) islets.

Objective: The objective of this study was to establish the cytotoxicity profile and to evaluate the insulin secretagogue effect of ethanolic root extract of Ravenala madagascariensis Sonn. Methods: The cell viability of rat insulinoma 5F (RIN5F) cell lines over the treatment of plant extract was assessed by 3-(4,5-dimethyl-2-thiazolyl)- 2,5-diphenyltetrazolium bromide assay. The insulin-releasing effect was evaluated by insulin secretion assay over RIN5F cell lines by enzyme-linked immunosorbent assay. Results: The ethanolic extract of the roots of R. madagascariensis Sonn. showed negligible cytotoxicity at 20–40 μg/ml, and hence, concentrations up to 40 μg/ml were used in insulin secretion assay. The ethanolic root extract at 20 and 40 μg/ml significantly (p

Through the integration of results from an imaging analysis of intracellular trafficking of labelled neurosecretory vesicles in chromaffin cells, we develop a Markov state model to describe their transport and binding kinetics. Our simulation results indicate that a spatial redistribution of neurosecretory vesicles occurs upon secretagogue stimulation leading vesicles to the plasma membrane where they undergo fusion thereby releasing adrenaline and noradrenaline. Furthermore, we find that this redistribution alone can explain the observed up-regulation of vesicle transport upon stimulation and its directional bias towards the plasma membrane. Parameter fitting indicates that in the deeper compartment within the cell, vesicle transport is asymmetric and characterised by a bias towards the plasma membrane. We also find that crowding of neurosecretory vesicles undergoing directed transport explains the observed accelerated recruitment of freely diffusing vesicles into directed transport upon stimulation.

We adapted a radioligand receptor binding assay for measuring insulin levels in unknown samples. The assay enables rapid and accurate determination of insulin concentrations in experimental samples, such as from insulin-secreting cells. The principle of the method is based on the binding competition of insulin in a measured sample with a radiolabeled insulin for insulin receptor (IR) in IM-9 cells. Both key components, radiolabeled insulin and IM-9 cells, are commercially available. The IR binding assay was used to determine unknown amounts of insulin secreted by MIN6 β cell line after stimulation with glucose, arginine, ornithine, dopamine, and serotonin. The experimental data obtained by the IR binding assay were compared to the results determined by RIA kits and both methods showed a very good agreement of results. We observed the stimulation of glucose-induced insulin secretion from MIN6 cells by arginine, weaker stimulation by ornithine, but inhibitory effects of dopamine. Serotonin effects were either stimulatory or inhibitory, depending on the concentration of serotonin used. The results will require further investigation. The study also clearly revealed advantages of the IR binding assay that allows the measuring of a higher throughput of measured samples, with a broader range of concentrations than in the case of RIA kits. The IR binding assay can provide an alternative to standard RIA and ELISA assays for the determination of insulin levels in experimental samples and can be especially useful in scientific laboratories studying insulin production and secretion by β cells and searching for new modulators of insulin secretion.

Background Bisacodyl is a member of the diphenylmethane family and is considered to be a stimulant laxative. It has a dual prokinetic and secretory action and needs to be converted into the active metabolite bis‐(p‐hydroxyphenyl)‐pyridyl‐2‐methane (BHPM) in the gut to achieve the desired laxative effect. Bisacodyl acts locally in the large bowel by directly enhancing the motility, reducing transit time, and increasing the water content of the stool. A recent network meta‐analysis concluded that bisacodyl showed similar efficacy to prucalopride, lubiprostone, linaclotide, tegaserod, velusetrag, elobixibat, and sodium picosulfate for the primary endpoint of ≥3 complete spontaneous bowel movements (CSBM)/week and an increase of ≥1 CSBM/week over baseline. The meta‐analysis also found that bisacodyl may be superior to the other laxatives for the secondary endpoint of change from baseline in the number of spontaneous bowel movements per week in patients with chronic constipation. This observation stimulated the authors to review the available literature on bisacodyl, which has been available on the market since the 1950 s. Purpose The aim of the current review was to provide an overview of the historic background, structure, function, and mechanism of action of bisacodyl. Additionally, we discuss the important features and studies for bisacodyl to understand its peculiar characteristics and guide its use in clinical practice, but also stimulate research on open questions.

Context We hypothesize, based on the degree of residual hypothalamic-pituitary function, that some, but not all, children with growth hormone deficiency (GHD) may have beneficial growth responses to the orally administered growth hormone (GH) secretagogue LUM-201. Objective To determine if pretreatment testing can identify predictive enrichment markers (PEM) for subjects with adequate residual function who are responsive to LUM-201. Methods We performed an analysis of a completed, randomized, placebo-controlled trial of LUM-201, a GH secretagogue receptor agonist, in which all randomized subjects had pretreatment testing. This international multicenter study conducted in pediatric endocrinology clinics included 68 naïve-to-treatment, prepubertal children with established diagnoses of GHD. Outcome measures included the sensitivity, specificity, and predictive accuracy of potential markers to predict 6-month growth responses to oral LUM-201 and daily rhGH. Results Two PEM were identified for use in defining PEM-positive status: (1) baseline insulin-like growth factor I (IGF-I) concentration >30 ng/mL and (2) peak GH response of ≥5 ng/mL upon administration of single-dose LUM-201. PEM-positive status enriches a population for better growth responses to LUM-201. PEM-negative status enriches a population for better growth responses to rhGH. Conclusion Combined, the peak GH response to single-dose LUM-201 and the baseline IGF-I concentration are effective PEMs for 6-month growth responses to LUM-201 and rhGH in prepubertal children with GHD.

Evidence based immunological cross-reactivity studies and anti-diabetic investigations have suggested the presence of insulin-like peptides in plants. Mcy protein, isolated from the fruits of Momordicacymbalaria, was shown to have antihyperglycemic, antihyperlipidemic activities along with renal as well as hepatoprotective activities in Streptozotocin induced diabetic rats.Mcy protein was shown to have insulin like and/or insulin secretagoguestructure and/or functions. Hence, the present study was conducted to elucidate molecular mechanism wherebyMcy protein elicits its therapeutic role and also to know whether the Mcyprotein has any structural and functional similarity with insulin. Results of our experiments revealed that the Mcyprotein is insulin like protein. Further, we assessed the effect of treatment of Mcy protein on the levels of glucose transport (glucose transporter (GLUT-2) and on the levels of key regulators of glucose and lipid metabolisms like hepatic glucokinase (GK) and sterol regulated element binding protein-1c (SREBP-1c). Our findings demonstrated that Mcy protein decreased the elevated expressions of GK, SREBP-1c and GLUT-2 that were observed in diabetic animals. Insulin-receptor binding studies using rat erythrocytes demonstrated that mean specific binding of insulin with insulin receptors was significantly increased in Mcy treated diabetic rats when compared to diabetic control rats. Scatchard analyses of insulin-binding studies yielded curvilinear plots, and the number of receptor sites per cell was found to be 180±21.1 in Mcy treated diabetic animals calculated to be significantly superior to that of diabetic control animals. Kinetic analyses also revealed an increase in the average receptor affinity of erythrocytes from Mcy treated rats compared to diabetic control rats suggesting acute alteration in the number and affinity of insulin receptors on the membranes of erythrocytes.

Context Recombinant human growth hormone (rhGH) is approved for treatment of pediatric growth hormone deficiency (GHD), with greatest growth responses observed in those with severe GHD. Orally administered GH secretagogues (GHS) may be useful treatment in patients with moderate GHD. Distinguishing children with severe vs moderate GHD could identify children who would be better treated with rhGH or GHS. Objectives Evaluate baseline insulin-like growth factor-I (IGF-I) and stimulated peak GH response as predictors of 12-month height velocity (HV) in children with GHD. Design Data on children with GHD were analyzed in a legacy data base (GeNeSIS data). Participants 514 naïve to rhGH-treatment, prepubertal children with idiopathic isolated GHD for whom stimulated GH, baseline serum IGF-I, and first-year HV during rhGH treatment data are available. Outcome Measures Children with severe or moderate GHD were categorized based on GH and IGF-I data and evaluated based on baseline auxologic and hormone profiles and first-year growth response to rhGH. Results Cohorts of severe and moderate GHD were 81/514 (15.8%) and 433/514 (84.2%). Cohorts differed significantly with regard to indicators of GHD [eg, baseline height SD score (SDS), height SDS minus target height SDS, HV, HV SDS, and change in height SDS during rhGH treatment]. Multiple regression analysis showed IGF-I and stimulated GH were significant predictors of HV independent of other known variables. Expected first-year HV in moderate GHD was 8.3 cm/y. Conclusions The combination of peak GH to GH stimulation testing and baseline IGF-I concentration are predictive enrichment markers for annualized HV responses to rhGH therapy.

A hallmark of enteroaggregative Escherichia coli (EAEC) infection is the formation of an intestinal biofilm, which comprises a mucus layer with immersed bacteria. Pic is an autotransporter secreted by EAEC, and other E. coli pathotypes, and has been involved in two apparently contradictory phenotypes, as a mucus secretagogue and as a mucinase. Here, we investigated this Pic dual activity, mucus secretagogue capability and mucinolytic activity, in human goblet cells that secrete MUC2 and MUC5AC. Pic induced mucus hypersecretion directly in the goblet cells, without other intestinal cell types involved. At the same time, Pic exhibited strong proteolytic activity on the secreted mucins. These activities were independent since a mutation in the serine protease motif (PicS258I) abolished mucin degradation while maintaining the mucus secretagogue activity intact. Furthermore, deoxycholic acid (DCA)-induced mucins were proteolytically degraded when goblet cells were co-incubated with DCA/Pic, while co-incubation with DCA/PicS258I induced a synergistic effect on mucus hypersecretion. Pic was more efficient degrading MUC5AC than MUC2, but no degradation was detected with Pic inactivated at the active site by mutation or pharmacological inhibition. Remarkably, Pic cleaved MUC2 and MUC5AC in the C-terminal domain, leaving N-terminal subproducts, impacting the feature of gel-forming mucins and allowing mucus layer penetration by EAEC. Astonishingly, Pic stimulated rapid mucin secretion in goblet-like cells by activating the intracellular calcium pathway resulting from the PLC signal transduction pathway, leading to the production of DAG and releasing IP3, a second messenger of calcium signaling. Therefore, the dual activity of Pic, as a mucus secretagogue and a mucinase, is relevant in the context of carbon source generation and mucus layer penetration, allowing EAEC to live within the layer of mucus but also access epithelial cells.

Background/Introduction The cardiovascular outcome study of linagliptin versus glimepiride in type 2 diabetes (CAROLINA) was designed to compare the effects on cardiovascular (CV) events, and other outcomes, of linagliptin with glimepiride in patients with relatively early type 2 diabetes with elevated CV risk Purpose These post hoc analyses of the CAROLINA randomized controlled trial explore outcomes in subgroups stratified by prior sulfonylurea (SU) or glinide use. Methods Participants with relatively early type 2 diabetes, high CV risk and HbA1c 6.5–8.5% were randomized to linagliptin 5 mg or glimepiride 1–4 mg once daily with standard of care. 29.5% of patients had prior SU/glinide use. SU/glinides were discontinued at trial entry. Outcomes included time to first CV death/MI/stroke (3P-MACE), time to all-cause mortality, HbA1c change from baseline and time to first hypoglycaemia event. Results 6033 participants received ≥1 study drug dose (mean [SD] age 64.0 [9.5] yrs, HbA1c 7.2 [0.6] %, median diabetes duration 6.3 yrs, 42% with CV disease); 897 linagliptin and 884 glimepiride participants had prior SU/glinide use. Results for 3P-MACE and all-cause mortality were consistent across subgroups with/without prior SU/glinide use (interaction p>0.05; Fig). After some initial differences, there was no meaningful difference in HbA1c between linagliptin vs glimepiride across SU/glinide subgroups and overall. Hypoglycaemia rates were lower with linagliptin vs glimepiride overall and across SU/glinide subgroups, with some heterogeneity for prior SU/glinide use (interaction p Conclusion There was no difference in linagliptin versus glimepiride on 3P-MACE and all-cause mortality, with consistent results across subgroups irrespective of prior SU/glinide use. Hypoglycaemia rates were consistently lower with linagliptin vs glimepiride, regardless of prior SU/glinide use. Funding Acknowledgement Type of funding source: Private company. Main funding source(s): Boehringer Ingelheim and Eli Lilly and Company

Oxalobacter formigenes has been investigated for years due to its proposed ability to produce a secretagogue compound that initiates net intestinal oxalate secretion, thereby theoretically reducing circulating oxalate and risk of kidney stone formation. Strains which have been shown to exhibit this function in vivo across native tissue include the human strain, HC1, and the wild rat strain, OxWR. While previous work on these secretagogue-relevant strains has focused on profiling their metabolome and lipidome in vitro, efforts to characterize their influence on host intestinal mucosal biochemistry in vivo are yet to be reported. Much work has been done over the years with O. formigenes in relation to the secretagogue hypothesis, but it has never been clearly demonstrated that this microorganism is capable of inducing metabolic changes in native host tissue, which would be expected with the production of a transport-inducing compound. In this work, we show how the distal colonic mucosal metabolomic profile in a mouse model exhibited significant changes in the levels of a variety of metabolites as a result of oral gavage with O. formigenes HC1. Among these significant metabolites was nicotinic acid, an essential nutrient shown in past work to be produced in the gut by the native microbiome. Our finding that the in vivo biochemical state of the distal colon was altered with O. formigenes lends support to the secretagogue hypothesis and serves as a pioneering step in characterizing the biochemical interplay between O. formigenes and the mammalian host.

Angiotensin II type 1 receptor blockers (ARBs), as antihypertensive drugs, have drawn attention for their benefits to individuals with diabetes and prediabetes. However, the effects of ARBs on insulin secretion remain unclear. Here, we investigated the insulinotropic effects of ARBs (telmisartan, valsartan, and irbesartan) and the underlying electrophysiological mechanism in rat islets. We found that only telmisartan among the three ARBs exhibited an insulin secretagogue role. Distinct from other ARBs, telmisartan exerted effects on ion channels including voltage-gated potassium (Kv) channels and voltage-gated Ca2+channels to promote extracellular Ca2+influx, thereby potentiating insulin secretion in a glucose-dependent manner. We observed that the peroxisome proliferator-activated receptor γ pathway was not involved in these telmisartan-induced effects. Furthermore, we identified that telmisartan at least directly inhibited Kv2.1 channel through construction of a Chinese hamster ovary cell line with Kv2.1 channel overexpression. Acute exposure of type 2 diabetes model (db/db) mice to a telmisartan dose equivalent to therapeutic doses in humans resulted in lower blood glucose and increased plasma insulin concentration in the oral glucose tolerance test. We further observed the telmisartan-induced insulinotropic and electrophysiological effects on pathological pancreatic islets isolated fromdb/dbmice. Collectively, our results establish an important function of telmisartan distinct from other ARBs in the treatment of diabetes.

Enteroendocrine (EE) cells within the intestinal epithelium produce a range of hormones that have key roles in modulating satiety and feeding behavior in humans. The regulation of hormone release from EE cells as a potential therapeutic strategy to treat metabolic disorders is highly sought after by the pharmaceutical industry. However, functional studies are limited by the scarcity of EE cells (or surrogates) in both in vivo and in vitro systems. Enterochromaffin (EC) cells are a subtype of EE cells that produce serotonin (5HT). Here, we explored simple strategies to enrich EC cells in in vitro monolayer systems derived from human primary intestinal stem cells. During differentiation of the monolayers, the EC cell lineage was significantly altered by both the culture method [air-liquid interface (ALI) vs submerged] and the presence of vasoactive intestinal peptide (VIP). Compared with traditional submerged cultures without VIP, VIP-assisted ALI culture significantly boosted the number of EC cells and their 5HT secretion by up to 430 and 390%, respectively. The method also increased the numbers of other subtypes of EE cells such as L cells. Additionally, this method generated monolayers with enhanced barrier integrity, so that directional (basal or apical) 5HT secretion was measurable. For all donor tissues, the enriched EC cells improved the signal-to-background ratio and reliability of 5HT release assays. The enhancement in the 5HT secretion behavior was consistent over time from a single donor, but significant variation in the amount of secreted 5HT was present among tissues derived from five different donors. To demonstrate the utility of the EC-enriched monolayer system, 13 types of pungent food ingredients were screened for their ability to stimulate 5HT secretion. Curcumin found in the spice turmeric derived from the Curcuma longa plant was found to be the most potent secretagogue. This EC-enriched cell monolayer platform can provide a valuable analytical tool for the high-throughput screening of nutrients and gut microbial components that alter the secretion of 5HT.

Lixisenatide, a glucagon-like peptide-1 receptor agonist, is used to stimulate insulin secretion in patients with type 2 diabetes mellitus. However, its effect on insulin secretion in cancer patients, particularly during the cachexia course, has not yet been evaluated. The purpose of this study was to investigate the lixisenatide effect on INS secretion decline during the cachexia course (2, 6, and 12 days of tumor) in pancreatic islets isolated from Walker-256 tumor-bearing rats. Pancreatic islets of healthy and tumor-bearing rats were incubated in the presence or absence of lixisenatide (10 nM). Tumor-bearing rats showed reduction of body weight and fat and muscle mass, characterizing the development of cachexia, as well as reduction of insulinemia and INS secretion stimulated by glucose (5.6, 8.3, 11.1, 16.7, and 20 mM) on days 2, 6, and/or 12 of tumor. Lixisenatide increased the 16.7 mM glucose-stimulated insulin secretion, but not by 5.6 mM glucose, in the islets of healthy rats, without changing the insulin intracellular content. However, lixisenatide did not prevent the decreased 16.7 mM glucose-stimulated insulin secretion in the pancreatic islets of rats with 2, 6, and 12 days of tumor and neither the decreased insulin intracellular content of rats with 12 days of tumor. In consistency, in vivo treatment with lixisenatide (50 μg kg−1, SC, once daily, for 6 days) visually increased insulinemia of healthy fasted rats, but did not prevent hypoinsulinemia of tumor-bearing rats. In conclusion, Walker-256 tumor-bearing rats showed early decline (2 days of tumor) of insulin secretion, which followed the cachexia course (6 and 12 days of tumor) and was not improved by lixisenatide, evidencing that this insulin secretagogue, used to treat type 2 diabetes, does not have beneficial effect in cancer bearing-rats.

Aims/hypothesis Insulin-like peptide-5 (INSL5) is found only in distal colonic L cells, which co-express glucagon-like peptide-1 (GLP-1) and peptide YY (PYY). GLP-1 is a well-known insulin secretagogue, and GLP-1 and PYY are anorexigenic, whereas INSL5 is considered orexigenic. We aimed to clarify the metabolic impact of selective stimulation of distal colonic L cells in mice. Methods Insl5 promoter-driven expression of Gq-coupled Designer Receptor Exclusively Activated by Designer Drugs (DREADD) was employed to activate distal colonic L cells (LdistalDq). IPGTT and food intake were assessed with and without DREADD activation. Results LdistalDq cell stimulation with clozapine N-oxide (CNO; 0.3 mg/kg i.p.) increased plasma GLP-1 and PYY (2.67- and 3.31-fold, respectively); INSL5 was not measurable in plasma but was co-secreted with GLP-1 and PYY in vitro. IPGTT (2 g/kg body weight) revealed significantly improved glucose tolerance following CNO injection. CNO-treated mice also exhibited reduced food intake and body weight after 24 h, and increased defecation, the latter being sensitive to 5-hydroxytryptamine (5-HT) receptor 3 inhibition. Pre-treatment with a GLP1 receptor-blocking antibody neutralised the CNO-dependent improvement in glucose tolerance but did not affect the reduction in food intake, and an independent group of animals pair-fed to the CNO-treatment group demonstrated attenuated weight loss. Pre-treatment with JNJ-31020028, a neuropeptide Y receptor type 2 antagonist, abolished the CNO-dependent effect on food intake. Assessment of whole body physiology in metabolic cages revealed LdistalDq cell stimulation increased energy expenditure and increased activity. Acute CNO-induced food intake and glucose homeostasis outcomes were maintained after 2 weeks on a high-fat diet. Conclusions/interpretation This proof-of-concept study demonstrates that selective distal colonic L cell stimulation has beneficial metabolic outcomes.

Irisin is a hormone secreted by skeletal muscle following physical activity and excess of saturated fatty acids, able to improve metabolic homeostasis and promote energy expenditure. In a previous study, we have demonstrated that, in beta-cells, irisin promotes proliferation and glucose-stimulated insulin secretion (GSIS), increases insulin content levels, and reduces lipotoxicity-induced apoptosis. The aim of this study was to evaluate the effects of irisin on the function and survival of pancreatic islets isolated from patients with type 2 diabetes mellitus (T2DM), characterized by reduced ability to secrete insulin and high levels of apoptosis, and to investigate the molecular mechanisms underlying this action. Pancreatic islets isolated from T2DM patients (n=7) and nondiabetic subjects (ND) (n=3), as well as INS-1E cells, were exposed to 100 nM irisin for different times. GSIS, insulin content, apoptosis and cytoplasmic calcium levels were measured by ELISA assays; the activation of the main mediators of beta-cell intracellular signalling (AKT, CREB and PKA) was evaluated by immunoblotting. Irisin increased GSIS approximately 2-fold (p In conclusion, the myokine irisin is able to increase the secretory function and survival of human pancreatic islets and to improve the functional defects typical of the T2DM islets. The mechanisms underlying the secretagogue effects of irisin in the T2DM islets do not apparently involve the known signaling machinery of this novel hormone. Disclosure N. Marrano: None. A. Natalicchio: Consultant; Self; AstraZeneca, Novo Nordisk Inc., Sanofi-Aventis. G. Biondi: None. A. Cignarelli: None. L. Vincenti: None. L.G. Lupo: None. S. Perrini: None. L. Laviola: Advisory Panel; Self; Abbott, AstraZeneca, Boehringer Ingelheim International GmbH, Eli Lilly and Company, Novo Nordisk Inc., Roche Diabetes Care, Sanofi-Aventis. Speaker’s Bureau; Self; Abbott, Medtronic. F. Giorgino: Advisory Panel; Self; AstraZeneca, Eli Lilly and Company, Novo Nordisk Inc., Roche Diabetes Care, Sanofi. Consultant; Self; AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., LifeScan, Inc., MedImmune, Merck Sharp & Dohme Corp., Roche Diabetes Care, Sanofi. Research Support; Self; Eli Lilly and Company, LifeScan, Inc., Takeda Development Centre Europe Ltd. Funding European Union (AIM1810057)

Introduction: The number of disabilities due to age is expected to double by 2060. In this scenario, the development of sarcopenia is an important risk factor for the development of frailty, loss of independence and physical disability in the elderly and is associated with lower survival in critically ill patients. In this sense, the decline in fat-free mass correlates with the decline associated with the age of growth hormone (GH) secretion. Thus, GH secretagogue (MK-677) as the first orally active ghrelin mimetic may increase pulsatile GH secretion in the elderly. Objective: The main objectives were to determine whether oral MK-677 in healthy elderly would increase GH and IGF-I levels, prevent the decline of FFM and decrease abdominal visceral fat (AVF) with acceptable tolerability. Methods: A total of 18 articles were found involving MK-677, GH secretagogue, sarcopenia, insulin-like growth factor-1, safety, and efficacy. Initially, it was held the existing exclusion title and duplications following the interest described in this work. After this process, 5 articles were included and discussed in this study. The present study was elaborated according to the rules of systematic review- PRISMA (Transparent reporting of systematic reviews and meta-analysis- http://www.prisma-statement.org/). Results: In a clinical study, MK-677 neutralized three important factors contributing to the development of sarcopenia, which is reduced GH secretion, fat-free mass loss, and inadequate food intake. A recent study looked at the safety and efficacy of the oral GH secretagogue (MK-677) in humans, showing that MK-677 promotes pulsatile GH release that is subject to negative feedback and may prevent supra-therapeutic levels. of GH and its sequelae. Available studies indicate that MK-677 is well tolerated, however, there is a bias in decreased insulin sensitivity. There were no adverse effects attributable to MK-677. However, MK-677 had an unfavorable safety profile in individuals with congestive heart failure. Conclusion: The most confirmed sarcopenia treatment methods are nutritional overfeeding and resistance training, but studies have shown that supplementation with MK-677 can significantly reduce three important factors contributing to the development of sarcopenia, which is reduced secretion. GH loss, fat-free mass loss, and inadequate food intake, safely and effectively. However, it is imperative to increase randomized clinical trials to establish a consensus treatment. Keywords: MK-677. Ibutamoren. GH secretagogue. Sarcopenia. Elderly.

We have examined the effects of α-aminoadipic acid, an oxidized derivative from the amino acid lysine, on the physiology of mouse pancreatic acinar cells. Changes in intracellular free-Ca2+ concentration, the generation of reactive oxygen species, the levels of carbonyls and thiobarbituric-reactive substances, cellular metabolic activity and trypsin secretion were studied. Stimulation of mouse pancreatic cells with cholecystokinin (1 nM) evoked a transient increase in [Ca2+]i. In the presence of α-amoniadipic acid increases in [Ca2+]i were observed. In the presence of the compound, cholecystokinin induced a Ca2+ response that was smaller compared with that observed when cholecystokinin was applied alone. Stimulation of cells with cholecystokinin in the absence of Ca2+ in the extracellular medium abolished further mobilization of Ca2+ by α-aminoadipic acid. In addition, potential pro-oxidant conditions, reflected as increases in ROS generation, oxidation of proteins and lipids, were noted in the presence of α-aminoadipic acid. Finally, the compound impaired trypsin secretion induced by the secretagogue cholecystokinin. We conclude that the oxidized derivative from the amino acid lysine induces pro-oxidative conditions and the impairment of enzyme secretion in pancreatic acinar cells. α-aminoadipic acid thus creates a situation that could potentially lead to disorders in the physiology of the pancreas.

Repaglinide, an oral hypoglycemic agent, is a short-acting insulin secretagogue. We describe a case, in which an extremely low dose of repaglinide caused severe hypoglycemia and novel drug interactions are suggested. A 71-year-old man with type 2 diabetes was taken to the hospital due to consciousness disorder caused by severe hypoglycemia. He was taking repaglinide 0.25 mg once in the morning with nilotinib 400 mg/day and febuxostat 20 mg/day. Endogenous insulin secretion was not suppressed even in hypoglycemia. Detection of plasma repaglinide 10 h after administration in this case indicates delayed elimination of the agent, which might be derived from reduced hepatocyte uptake due to inhibitory effects of nilotinib on OATP1B1 and reduced oxidation of the agents by inhibitory effects of nilotinib, mainly on CYP3A4 activities, and of febuxostat on CYP2C8 activities. Repaglinide is eliminated by the liver, and is a short-acting insulin secretagogue with a good safety profile in patients with type 2 diabetes complicated by renal impairment, including elderly patients; however, its delayed elimination due to drug–drug interactions should be noted.

Objective Binding of ghrelin to its receptor, growth hormone secretagogue receptor (GHSR), stimulates GH release, induces eating, and increases blood glucose. These processes may also be influenced by constitutive (ghrelin-independent) GHSR activity, as suggested by findings in short people with naturally occurring GHSR-A204E mutations and reduced food intake and blood glucose in rodents administered GHSR inverse agonists, both of which impair constitutive GHSR activity. In this study, we aimed to more fully determine the physiologic relevance of constitutive GHSR activity. Methods We generated mice with a GHSR mutation that replaces alanine at position 203 with glutamate (GHSR-A203E), which corresponds to the previously described human GHSR-A204E mutation, and used them to conduct ex vivo neuronal electrophysiology and in vivo metabolic assessments. We also measured signaling within COS-7 and HEK293T cells transfected with wild-type GHSR (GHSR-WT) or GHSR-A203E constructs. Results In COS-7 cells, GHSR-A203E resulted in lower baseline IP3 accumulation than GHSR-WT; ghrelin-induced IP3 accumulation was observed in both constructs. In HEK293T cells co-transfected with voltage-gated CaV2.2 calcium channel complex, GHSR-A203E had no effect on basal CaV2.2 current density while GHSR-WT did; both GHSR-A203E and GHSR-WT inhibited CaV2.2 current in the presence of ghrelin. In cultured hypothalamic neurons from GHSR-A203E and GHSR-deficient mice, native calcium currents were greater than those in neurons from wild-type mice; ghrelin inhibited calcium currents in cultured hypothalamic neurons from both GHSR-A203E and wild-type mice. In brain slices, resting membrane potentials of arcuate NPY neurons from GHSR-A203E mice were hyperpolarized compared to those from wild-type mice; the same percentage of arcuate NPY neurons from GHSR-A203E and wild-type mice depolarized upon ghrelin exposure. The GHSR-A203E mutation did not significantly affect body weight, body length, or femur length in the first ∼6 months of life, yet these parameters were lower in GHSR-A203E mice after 1 year of age. During a 7-d 60% caloric restriction regimen, GHSR-A203E mice lacked the usual marked rise in plasma GH and demonstrated an exaggerated drop in blood glucose. Administered ghrelin also exhibited reduced orexigenic and GH secretagogue efficacies in GHSR-A203E mice. Conclusions Our data suggest that the A203E mutation ablates constitutive GHSR activity and that constitutive GHSR activity contributes to the native depolarizing conductance of GHSR-expressing arcuate NPY neurons. Although the A203E mutation does not block ghrelin-evoked signaling as assessed using in vitro and ex vivo models, GHSR-A203E mice lack the usual acute food intake response to administered ghrelin in vivo. The GHSR-A203E mutation also blunts GH release, and in aged mice leads to reduced body length and femur length, which are consistent with the short stature of human carriers of the GHSR-A204E mutation., Graphical abstract Image 1, Highlights • We generated mice with a GHSR mutation replacing Ala at position 203 with Glu. • The A203E mutation ablates constitutive GHSR activity & hyperpolarizes NPY neurons. • GHSR-A203E mice lack the usual orexigenic response to administered ghrelin. • The GHSR-A203E mutation blunts GH release and causes reduced body length. • This finding is consistent with short stature in human carriers of the GHSR-A204E mutation.

Background: Dyslipidaemias are common in patients with diabetes mellitus. A high prevalence of type 2 diabetes in hyperlipidaemic patients also exists. The aim of this study was to find a treatment that lowers both blood glucose and lipid levels simultaneously. Methods: The hypolipidaemic effect of (R)-(−)-carvone was investigated in a tyloxapol- induced hyperlipidaemia mice model. Furthermore, its effect on insulin secretion and proliferation of 1.1E7 human pancreatic β-cells was studied. In addition, using molecular docking, the binding affinity of (R)-(−)-carvone against 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG- CoA) reductase was estimated. Results: (R)-(−)-carvone (100 mg/kg) decreased plasma triglyceride, total cholesterol, low-density lipoprotein cholesterol (LDL-C) levels and atherogenic index by 90.6%, 49.3%, 56.6% and 70.3%, respectively, but it had no effect on high-density lipoprotein cholesterol (HDL-C). Furthermore, it increased hepatic triglyceride level and catalase activity by 79.6% and 59.6%, respectively. In-vitro, 500 μM (R)-(−)-carvone increased insulin secretion by 454.4% and proliferation of 1.1E7 cells with no cytotoxic effects up to a concentration of 100 μM. Molecular docking simulation demonstrated a good binding affinity with –5.03 Kcal/mol of (R)-(−)-carvone to HMG-CoA reductase. Conclusion: The hypolipidaemic effect of (R)-(−)-carvone is comparable to that of fenofibrate. (R)-(−)-carvone has the advantage over fenofibrate of not producing hypoglycaemia in animals. Furthermore, (R)-(−)-carvone increased proliferation and insulin secretion of human pancreatic β-cells.

Introduction: Motilin was first alluded to nearly a century ago. But it remains a rather abstruse peptide, in the shadow of its younger but more lucid 'cousin' ghrelin.Areas covered: The review aimed to bring to the fore multifarious aspects of motilin research with a view to aiding prioritization of future studies on this gastrointestinal peptide.Expert opinion: Growing evidence indicates that rodents (mice, rats, guinea pigs) do not have functional motilin system and, hence, studies in these species are likely to have a minimal translational impact. Both the active peptide and motilin receptor were initially localized to the upper gastrointestinal tract only but more recently - also to the brain (in both humans and other mammals with functional motilin system). Motilin is now indisputably implicated in interdigestive contractile activity of the gastrointestinal tract (in particular, gastric phase III of the migrating motor complex). Beyond this role, evidence is building that there is a cross-talk between motilin system and the brain-pancreas axis, suggesting that motilin exerts not only contractile but also orexigenic and insulin secretagogue actions.

Previously we identified a sodium caseinate (NaCas) hydrolysate, LFC25, which significantly increased secretion of satiety hormone glucagon-like peptide-1 (GLP-1) in vitro and reduced food intake in mice when administered intraperitoneally. This study investigates whether LFC25, administered orally, promotes GLP-1 secretion and/or reduces food intake in vivo. Over an 8-hour period, mice received LFC25 by oral gavage had similar food intake to mice received NaCas. Postprandial blood glucose, plasma active GLP-1, amino acids, insulin and food consumed at the next meal were not significantly different in pigs that consumed LFC25 compared to NaCas in a dairy beverage, at a dosage relevant for human consumption. Simulated in vitro gastro-duodenal digestion of LFC25 revealed a significant reduction in bioactivity. In contrast, the harsh conditions of the upper gut appear to functionalize intact NaCas as a GLP-1 secretagogue. In conclusion, LFC25 will need enteric protection to be used as a food ingredient for satiety.

Intra-pancreatic activation of the digestive proteases trypsin and chymotrypsin is an early event in the development of pancreatitis. Human genetic studies indicate that chymotrypsin controls trypsin activity via degradation, but there is no evidence of this from animal models. We used CRISPR-Cas9 to disrupt the chymotrypsinogen B1 gene (Ctrb1) in C57BL/6N mice and induced pancreatitis in CTRB1-deficient and C57BL/6N (control) mice by administration of cerulein. CTRB1-deficient mice given cerulein had significant increases in intra-pancreatic trypsin activity and developed more severe pancreatitis compared with control mice. CTRB1 therefore protects against secretagogue-induced pancreatitis by reducing trypsin activity. Protease inhibitors developed for treatment of pancreatitis should be designed to target trypsin but not chymotrypsin.

Objective: The objectives of this case report are to describe an unusual presentation of Graves disease presenting with life-threatening hypoglycemia and to discuss rarely considered physiological mechanisms involved in this patient's hypoglycemia.Methods: Clinical evaluation in this case report involved multiple laboratory assays directed towards the confirmation and further evaluation of the potential etiology of the hypoglycemia. Insulin-mediated etiologies of hypoglycemia, hypoglycemia secondary to ingestion of sulfonylureas and glinides, and the patient's hypothalamic-pituitary-adrenal axis were evaluated through assessment of serum insulin, C-peptide, proinsulin, ACTH-stimulated cortisol, and insulin secretagogue serum concentrations.Results: Hypoglycemia associated with thyrotoxicosis is a rare phenomenon. We excluded insulin-mediated causes of hypoglycemia (given undetectable serum proinsulin, insulin, and C-peptide in the setting of concomitant hypoglycemia), oral hypoglycemic agents (given negative serum screen for sulfonylureas and glinides), and adrenal insufficiency (given a normal cosyntropin stimulation test result). Given the negative workup for common causes of hypoglycemia, more esoteric etiologies of hypoglycemia were considered leading to our working hypothesis of hypoglycemia due to a combination of thyrotoxicosis, hepatic glycogen depletion, and β-blocker-induced impaired glucoregulation.Conclusion: We report a rare case of hypoglycemia that serves as a lesson in physiology and underscores the need to consider atypical combined etiologies for hypoglycemia and judicious use of therapeutic agents. Under certain conditions, hyperthyroidism may contribute to hypoglycemia, demonstrating the possible physiological interplay between hyperthyroidism and severe hepatic glycogen depletion, followed by the additional pharmacological insult of β-blockade therapy, resulting in further impairment in peripheral glucose mobilization.

BACKGROUND: Pre-operative detection of corticotropin (ACTH) secreting microadenomas causing Cushing's disease (CD) improves surgical outcomes. Current best magnetic resonance imaging fails to detect up to 40% of these microadenomas. (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET) is specific, but not sensitive in detecting corticotropinomas. Theoretically, secretagogue stimulation with corticotropin releasing hormone (CRH) could improve detection of adenomas with (18)F-FDG PET. Previous attempts with simultaneous CRH stimulation have failed to demonstrate increased (18)F-FDG uptake in corticotropinomas. We hypothesized that CRH stimulation leads to a delayed elevation in glucose uptake in corticotropinomas. METHODS: Clinical data was analyzed for efficacy of CRH in improving (18)FDG-PET detection of corticotropinomas in CD. Glucose transporter 1 (GLUT1) immunoreactivity was performed on surgical specimens. Ex-vivo, viable cells from these tumors were tested for secretagogue effects (colorimetric glucose uptake), and for fate of intracellular glucose (glycolysis stress analysis). Validation of ex-vivo findings was performed with AtT-20 cells. RESULTS: CRH increased glucose uptake in human-derived corticotroph tumor cells and AtT-20, but not in normal murine or human corticotrophs (p

Increasing evidence suggests a role for ghrelin in the control of articular inflammatory diseases like osteoarthritis (OA). In the present study we examined the ability of ghrelin to counteract LPS-induced necrosis and apoptosis of chondrocytes and the involvement of GH secretagogue receptor (GHS-R)1a in the protective action of ghrelin. The effects of ghrelin (10−7–10−11 mol/L) on equine primary cultured chondrocytes viability and necrosis in basal conditions and under LPS treatment (100 ng/ml) were detected by using both acridine orange/propidium iodide staining and annexin-5/propidium iodide staining. The presence of GHS-R1a on chondrocytes was detected by Western Blot. The involvement of the GHS-R1a in the ghrelin effect against LPS-induced cytotoxicity was examined by pretreating chondrocytes with D-Lys3-GHRP-6, a specific GHS-R1a antagonist, and by using des-acyl ghrelin (DAG, 10−7 and 10−9 mol/L) which did not recognize the GHS-R 1a. Low ghrelin concentrations reduced chondrocyte viability whereas 10−7 mol/L ghrelin protects against LPS-induced cellular damage. The protective effect of ghrelin depends on the interaction with the GHS-R1a since it is significantly reduced by D-Lys3-GHRP-6. The negative action of ghrelin involves caspase activation and could be due to an interaction with a GHS-R type different from the GHS-R1a recognized by both low ghrelin concentrations and DAG. DAG, in fact, induces a dose-dependent decrease in chondrocyte viability and exacerbates LPS-induced damage. These data indicate that ghrelin protects chondrocytes against LPS-induced damage via interaction with GHS-R1a and suggest the potential utility of local GHS-R1a agonist administration to treat articular inflammatory diseases such as OA.

Achillea millefolium L. (Asteraceae) is a perennial herb used in Mexican folk medicine for treatment of several pathologies, including inflammatory and spasmodic gastrointestinal disorders, hepatobiliary complaints, overactive cardiovascular, respiratory ailments and diabetes.To evaluate the potential antidiabetic effect in vivo and to establish the potential mode of action through in vitro approaches of Achillea millefolium.The antidiabetic effect of hydroalcoholic extract of Achillea millefolium (HAEAm) was evaluated on the oral glucose tolerance tests, in normoglycemic and experimental Type 2 diabetic mice models. In addition, we evaluated the possible mode of action in in vitro assays to determine α-glucosidases inhibition, the insulin secretion and calcium mobilization in RINm5F cells and PPARγ and GLUT4 expression in 3T3-L1 cells.HAEAm showed significant glucose diminution on oral glucose tolerance test and in acute experimental Type 2 diabetic assay with respect to the control (p0.05). In addition, HAEAm promoted the α-glucosidases inhibition by 55% at 1mg/ml respect to control. On the other hand, HAEAm increased the PPARγ (five-times) and GLUT4 (two-fold) relative expression than control (p0.05). Finally, HAEAm significantly increased the insulin secretion and [CaThe HAEAm possesses in vivo antidiabetic effect, having such effect through multitarget modes of action that involve antihyperglycemic (α-glucosidases inhibition), hypoglycemic (insulin secretion) and potential insulin sensitizer (PPARγ/GLUT4 overexpression) actions.

Eriodictyol, a flavonoid isolated from Lyonia ovalifolia, was found to be the most potent insulin secretagogue in our preliminary studies. Here, we explored mechanism(s) of insulin secretory activity of eriodictyol in vitro and in vivo. Mice islets and MIN6 cells were incubated in basal and stimulatory glucose containing eriodictyol with or without agonist/antagonist. Secreted insulin and cAMP contents were measured using ELISA kits. K+- and Ca2+-channels currents were recorded with patch-clamp technique. Oral glucose tolerance test and plasma insulin was evaluated in non-diabetic and diabetic rats. Eriodictyol stimulated insulin secretion from mice islets and MIN6 cells only at stimulatory glucose concentrations with maximum effect at 200μM. Eriodictyol showed no pronounced effect on inward rectifying K+ and Ca2+ currents. Furthermore, in KCl depolarized islets, in the presence of diazoxide, insulin secretory ability of eriodictyol was enhanced. IBMX, a phosphodiesterase inhibitor, significantly (P

Phototoxicity is the most common problem investigators may encounter when performing live cell imaging. It develops due to excess laser exposure of cells loaded with fluorophores and can lead to often overlooked but significant artifacts, such as massive increase of intracellular Ca2+ concentration, which would make data interpretation problematic. Because information about laser- and dye-related changes in cytoplasmic calcium concentration is very limited, we aimed to describe this phenomenon to help investigators using laser scanning confocal microscopy in a non-invasive way. Therefore, in the present study we evaluated fluorescent fluctuations, which evolved in Fluo-3/4/8 loaded mouse pancreatic acinar cells during very low intensity laser excitation. We demonstrate that after standard loading procedure (2 µM Fluo-3/4/8-AM, 30 min at room temperature), applying 488 nm laser at as low as ca. 10 µW incident laser power (0.18 µW/µm2) at 1 Hz caused repetitive, 2-3 fold elevations of the resting intracellular fluorescence. The first latency and the pattern of the fluorescence fluctuations were laser power dependent and were related to Ca2+-release from intracellular stores, as they were abolished by BAPTA-AM treatment in Ca2+-free medium, but were not diminished by the reactive oxygen species (ROS) scavenger DMPO. Worryingly enough, the qualitative and quantitative features of the Ca2+-waves were practically indistinguishable from the responses evoked by secretagogue stimulation. Since using similar imaging conditions, a number of other cell types were reported to display spontaneous Ca2+ oscillations, we propose strategies to distinguish the real signals from artifacts.