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According to previous reports, diabetes seems to be a risk factor which worsens the serious clinical events caused by COVID-19. But is diabetes per se a risk factor that increases the probability of getting the virus? This paper will discuss this point. There are not many research data on antidiabetic drugs in this context. The potential influence of glucose-lowering agents on the severity of COVID-19 has not been described yet. Dipeptidylpeptidase-4 (DPP-4) is a cell surface protein ubiquitously expressed in many tissues and it is also a soluble molecule found in serum/plasma fluids. DPP-4 is involved in infection of cells by some viruses. This paper reviews data about the use of DPP-4 inhibitors and others diabetes drugs on COVID-19 patients. As such, no available evidence has yet suggested that glucose-lowering drugs - including those targeting DPP4-related pathways - produce any significant harm or benefit in the context of human infections. However, insulin must remain the first-choice agent in the management of critically ill-hospitalized patients, while it is recommended to suspend other agents in unstable patients. This paper provides related French and international recommendations for people with diabetes who got infected by COVID-19 and upholds that infections may alter glucose control and may require additional vigilance., D’après les dernières analyses de cas notamment en Chine et en Italie, le diabète semble être un facteur de risque d’aggravation de l’état clinique d’un patient atteint par le COVID-19 mais est-il un facteur de susceptibilité ? Une analyse de la littérature à la date du 6 mai 2020 tente de répondre à la question. Les données concernant le type de traitement antidiabétique à utiliser dans ces circonstances et son impact éventuel sur l’état clinique d’un patient infecté par le COVID-19 sont très rares. La dipeptidylpeptidase 4 (DPP-4), glycoprotéine membranaire ubiquitaire présente à la surface de nombreuses cellules et existant aussi sous forme soluble, est impliquée dans les réponses immunitaires inflammatoires en modifiant la production de plusieurs cytokines. La DPP-4 est impliquée dans l'infection des cellules par certains virus. Nous abordons la question de l’utilisation des inhibiteurs des DPP-4 chez les patients diabétiques et il n’y a pas à ce jour de données qui indiquent que l’état clinique des patients dépend de leur utilisation. De la même façon, l’utilisation de la metformine, des sulfamides hypoglycémiants, des analogues du GLP1 comme de l’insuline n’ont pas fait l’objet d’études dans ce contexte. Il nous parait prudent en phase aigüe de la maladie, en particulier chez les patients nécessitant un séjour en unités de soins intensifs de privilégier l’insuline chez eux. A la lumière d’une revue des recommandations sur la prise en charge des diabétiques,l’optimisation du contrôle glycémique est à privilégier et plusieurs messages clefs délivrés par les Sociétés savantes concluent ce travail.

Background Patients with insulin-treated type 2 diabetes (T2D) have a high risk of major adverse cardiovascular events. Sodium-glucose cotransporter inhibitors (SGLTi) improve outcomes without hypoglycaemic risk. Aims To study the effect of SGLTi in patients with T2D with and without background insulin treatment in outcome-driven RCTs. Methods Random effects models. Results A total of 54 374 patients with T2D were included in the analysis, of which 26 551 (48.8%) were treated with insulin. For 3P-MACE in patients without insulin treatment, the HR (95% CI) for the effect of SGLTi vs placebo was 0.93 (0.81–1.05), with moderate heterogeneity (I2 = 49.2%, Q statistic P = 0.11). In insulin-treated patients, the HR (95% CI) was 0.88 (0.82–0.95), without evidence of heterogeneity (I2 =0.0%, Q statistic P =0.91). The pooled effect evidenced a 10% reduction of 3P-MACE with SGLTi (HR: 0.90, 95% CI: 0.85–0.96), without SGLTi-by-insulin interaction P = 0.53. For the composite outcome of HF hospitalisation or cardiovascular death in patients without insulin treatment, the HR (95% CI) for the effect of SGLTi vs placebo was 0.77 (0.61-0.92), with marked heterogeneity (I2 = 66.8%, Q statistic P = 0.02). In insulin-treated patients, the HR (95% CI) was 0.77 (0.68–0.86), without significant heterogeneity (I2 = 31.7%, Q statistic P = 0.25). The pooled effect evidenced a 23% reduction of HF hospitalisations or cardiovascular death with SGLTi (HR: 0.77, 95% CI: 0.68–0.85), without SGLTi-by-insulin interaction P = 0.98. Conclusion SGLTi reduces cardiovascular events regardless of insulin use. However, the treatment effect is more homogeneous among insulin-treated patients, supporting the use of SGLTi for the treatment of patients with T2D requiring insulin for glycaemic control.

The pathophysiological study of diabetes mellitus took an important place in the school of Montpellier since the end of the XIXth century with Emmanuel Hedon's (1863-1933) contribution to the demonstration of the endocrine function of the pancreas. In 1942, a new sulfonamide compound (2254RP) was tested in the infectious diseases department of Pr M. Janbon (1898-1996) on cases of typhoid fever, leading to several deaths rapidly related to hypoglycaemia. The physiologist Auguste Loubatières (1912-1977) rapidly demonstrated that this hypoglycaemic effect required the presence of pancreas and was explained by stimulation of insulin secretion. He contributed to the description of a hypoglycaemic effect of several other sulphonamide compounds. He considered the diagnostic and therapeutic relevance of this class of drugs. This is a good example of a medical discovery combining a favourable local environment, serendipity and perfect experimental approach., La physiopathologie du diabète tient une place importante au sein de l’École de Montpellier dès la fin du XIXe siècle, avec les travaux d’Emmanuel Hédon (1863–1933) qui contribuent à la démonstration de la fonction endocrine du pancréas. En 1942, l’essai à Montpellier dans le service d’infectiologie du Pr M. Janbon (1898–1996) d’un nouveau sulfamide, le 2254RP chez des patients atteints de typhoïde provoque plusieurs décès vite rapportés à une hypoglycémie provoquée par cette nouvelle molécule. Le physiologiste Auguste Loubatières (1912–1977) démontre vite que cette hypoglycémie suppose la présence du pancréas et résulte d’une stimulation de la production d’insuline. Il contribue à démontrer l’efficacité d’autres sulfamides. Il envisage d’emblée l’intérêt diagnostique et thérapeutique de cette classe de médicaments. Il s’agit d’un bel exemple d’avancée médicale alliant présence d’un terreau local porteur, hasard et travail expérimental exemplaire.

International audience; Background: A closed-loop system of insulin delivery (also called an artificial pancreas) may improve glycemic outcomes in children with type 1 diabetes.Methods: In a 16-week, multicenter, randomized, open-label, parallel-group trial, we assigned, in a 3:1 ratio, children 6 to 13 years of age who had type 1 diabetes to receive treatment with the use of either a closed-loop system of insulin delivery (closed-loop group) or a sensor-augmented insulin pump (control group). The primary outcome was the percentage of time that the glucose level was in the target range of 70 to 180 mg per deciliter, as measured by continuous glucose monitoring.Results: A total of 101 children underwent randomization (78 to the closed-loop group and 23 to the control group); the glycated hemoglobin levels at baseline ranged from 5.7 to 10.1%. The mean (±SD) percentage of time that the glucose level was in the target range of 70 to 180 mg per deciliter increased from 53±17% at baseline to 67±10% (the mean over 16 weeks of treatment) in the closed-loop group and from 51±16% to 55±13% in the control group (mean adjusted difference, 11 percentage points [equivalent to 2.6 hours per day]; 95% confidence interval, 7 to 14; P

Objective Sodium-glucose cotransporter 2 (SGLT2) inhibitors (SGLT2i), or gliflozins, are anti-diabetic drugs that lower glycemia by promoting glucosuria, but they also stimulate endogenous glucose and ketone body production. The likely causes of these metabolic responses are increased blood glucagon levels, and decreased blood insulin levels, but the mechanisms involved are hotly debated. This study verified whether or not SGLT2i affect glucagon and insulin secretion by a direct action on islet cells in three species, using multiple approaches. Methods We tested the in vivo effects of two selective SGLT2i (dapagliflozin, empagliflozin) and a SGLT1/2i (sotagliflozin) on various biological parameters (glucosuria, glycemia, glucagonemia, insulinemia) in mice. mRNA expression of SGLT2 and other glucose transporters was assessed in rat, mouse, and human FACS-purified α- and β-cells, and by analysis of two human islet cell transcriptomic datasets. Immunodetection of SGLT2 in pancreatic tissues was performed with a validated antibody. The effects of dapagliflozin, empagliflozin, and sotagliflozin on glucagon and insulin secretion were assessed using isolated rat, mouse and human islets and the in situ perfused mouse pancreas. Finally, we tested the long-term effect of SGLT2i on glucagon gene expression. Results SGLT2 inhibition in mice increased the plasma glucagon/insulin ratio in the fasted state, an effect correlated with a decline in glycemia. Gene expression analyses and immunodetections showed no SGLT2 mRNA or protein expression in rodent and human islet cells, but moderate SGLT1 mRNA expression in human α-cells. However, functional experiments on rat, mouse, and human (29 donors) islets and the in situ perfused mouse pancreas did not identify any direct effect of dapagliflozin, empagliflozin or sotagliflozin on glucagon and insulin secretion. SGLT2i did not affect glucagon gene expression in rat and human islets. Conclusions The data indicate that the SGLT2i-induced increase of the plasma glucagon/insulin ratio in vivo does not result from a direct action of the gliflozins on islet cells., Highlights • Gliflozins (SGLT2 and SGLT1/2 inhibitors) increase plasma glucagon/insulin ratio. • SGLT2 is not expressed in rodent and human pancreatic α- and β-cells. • SGLT1 is however expressed in human α-cells. • SGLT2 and SGLT1/2 inhibitors do not directly affect glucagon and insulin secretion.

OBJECTIVE To evaluate the respective contributions of short-term glycemic variability and mean daily glucose (MDG) concentration to the risk of hypoglycemia in type 1 diabetes. RESEARCH DESIGN AND METHODS People with type 1 diabetes (n = 100) investigated at the University Hospital of Montpellier (France) underwent continuous glucose monitoring (CGM) on two consecutive days, providing a total of 200 24-h glycemic profiles. The following parameters were computed: MDG concentration, within-day glycemic variability (coefficient of variation for glucose [%CV]), and risk of hypoglycemia (presented as the percentage of time spent below three glycemic thresholds: 3.9, 3.45, and 3.0 mmol/L). RESULTS MDG was significantly higher, and %CV significantly lower (both P < 0.001), when comparing the 24-h glycemic profiles according to whether no time or a certain duration of time was spent below the thresholds. Univariate regression analyses showed that MDG and %CV were the two explanatory variables that entered the model with the outcome variable (time spent below the thresholds). The classification and regression tree procedure indicated that the predominant predictor for hypoglycemia was %CV when the threshold was 3.0 mmol/L. In people with mean glucose ≤7.8 mmol/L, the time spent below 3.0 mmol/L was shortest (P < 0.001) when %CV was below 34%. CONCLUSIONS In type 1 diabetes, short-term glycemic variability relative to mean glucose (i.e., %CV) explains more hypoglycemia than does mean glucose alone when the glucose threshold is 3.0 mmol/L. Minimizing the risk of hypoglycemia requires a %CV below 34%.

Objective: A single bout of exercise followed by intake of carbohydrates leads to glycogen supercompensation in prior exercised muscle. Our objective was to illuminate molecular mechanisms underlying this phenomenon in skeletal muscle of man. Methods: We studied the temporal regulation of glycogen supercompensation in human skeletal muscle during a 5 day recovery period following a single bout of exercise. Nine healthy men depleted (day 1), normalized (day 2) and supercompensated (day 5) muscle glycogen in one leg while the contralateral leg served as a resting control. Euglycemic hyperinsulinemic clamps in combination with leg balance technique allowed for investigating insulin-stimulated leg glucose uptake under these 3 experimental conditions. Cellular signaling in muscle biopsies was investigated by global proteomic analyses and immunoblotting. We strengthened the validity of proposed molecular effectors by follow-up studies in muscle of transgenic mice. Results: Sustained activation of glycogen synthase (GS) and AMPK in combination with elevated expression of proteins determining glucose uptake capacity were evident in the prior exercised muscle. We hypothesize that these alterations offset the otherwise tight feedback inhibition of glycogen synthesis and glucose uptake by glycogen. In line with key roles of AMPK and GS seen in the human experiments we observed abrogated ability for glycogen supercompensation in muscle with inducible AMPK deletion and in muscle carrying a G6P-insensitive form of GS in muscle. Conclusion: Our study demonstrates that both AMPK and GS are key regulators of glycogen supercompensation following a single bout of glycogen-depleting exercise in skeletal muscle of both man and mouse. Keywords: AMP-activated protein kinase (AMPK), TBC1 domain family member 4 (TBC1D4), Glycogen synthase (GS), Glucose uptake, Exercise, Insulin action

International audience; Adaptation of organisms to ever-changing nutritional environments relies on sensor tissues and systemic signals. Identification of these signals would help understand the physiological crosstalk between organs contributing to growth and metabolic homeostasis. Here we show that Eiger, the Drosophila TNF-α, is a metabolic hormone that mediates nutrient response by remotely acting on insulin-producing cells (IPCs). In the condition of nutrient shortage, a metalloprotease of the TNF-α converting enzyme (TACE) family is active in fat body (adipose-like) cells, allowing the cleavage and release of adipose Eiger in the hemolymph. In the brain IPCs, Eiger activates its receptor Grindelwald, leading to JNK-dependent inhibition of insulin production. Therefore, we have identified a humoral connexion between the fat body and the brain insulin-producing cells relying on TNF-α that mediates adaptive response to nutrient deprivation.

International audience; In occidental societies, high fat and high sugar diets often coincide with episodes of stress. The association is likely to modify brain energy control. Brain insulin signalling is rarely studied in stressed individuals consuming high fat diets. Furthermore the effects of cinnamon supplement are not known in these conditions. Therefore, we exposed rats, over a 12-week period, to a control (C) or a high fat/high fructose (HF/HFr) diet that induces peripheral insulin resistance. A cinnamon supplement (C+CN and HF/HFr +CN) was added or not. After diet exposure, one group of rats was exposed to a 30-min restraint followed by a 10-min open-field test, their combination featuring a moderate stressor, the other rats staying unstressed in their home cages. The insulin signalling in hippocampus and frontal cortex was studied through the mRNA expression of the following genes: insulin receptor (Ir), insulin receptor substrate (Irs1), glucose transporters (Glut1 and Glut3), glycogen synthase (Gys1) and their modulators, Akt1 and Pten. In C rats, stress enhanced the expression of Ir, Irs1, Glut1, Gys1 and Akt1 mRNA. In C+CN rats, stress induced an increase in Pten but a decrease in Gys1 mRNA expression. In HF/HFr rats, stress was associated with an increase in Pten mRNA expression. In HF/HFr+CN rats, stress increased Pten mRNA expression but also decreased Gys1 mRNA expression. This suggests that a single moderate stress favours energy refilling mechanisms, an effect blunted by a previous HF/HFr diet and cinnamon supplement.

Wolfram syndrome (WFS) is a rare autosomal recessive disease with non-autoimmune childhood onset insulin dependent diabetes and optic atrophy. WFS type 2 (WFS2) differs from WFS type 1 (WFS1) with upper intestinal ulcers, bleeding tendency and the lack ofdiabetes insipidus. Li-fespan is short due to related comorbidities. Only a few familieshave been reported with this syndrome with the CISD2 mutation. Here we report two siblings with a clinical diagnosis of WFS2, previously misdiagnosed with type 1 diabetes mellitus and diabetic retinopathy-related blindness. We report possible additional clinical and laboratory findings that have not been pre-viously reported, such as asymptomatic hypoparathyroidism, osteomalacia, growth hormone (GH) deficiency and hepatomegaly. Even though not a requirement for the diagnosis of WFS2 currently, our case series confirm hypogonadotropic hypogonadism to be also a feature of this syndrome, as reported before.Zespół Wolframa jest rzadką chorobą dziedziczoną autosomalnie recesywnie, wiążącą się z występowaniem nieautoimmunizacyjnej cukrzycy insulinozależnej i atrofii nerwu wzrokowego. Typ 2 zespołu Wolframa (WFS2) różni się od typu 1 (WFS1) występowaniem owrzodzeń górnej części przewodu pokarmowego, skłonnością do krwawień i niewystępowaniem moczówki prostej. Czas przeżycia jest krótki ze względu na współwystępujące choroby. Dotychczas opisano tylko kilka rodzin z tym zespołem i mutacją CISD2. W obecnej pracy opisujemy przypadek rodzeństwa z kliniczną diagnozą WFS2, wcześniej zdiagnozowanego jako cukrzyca typu 1 z retinopatią powikłaną utratą wzroku. Opisujemy możliwe dodatkowe kliniczne i laboratoryjne parametry, które nie były wcześniej opisywane, takie jak: bezobjawowa niedoczynność przytarczyc, osteomalacja, niedobór hormonu wzrostu i hepatomegalia. Pomimo braku wymogu do rozpoznania zespołu WSF2 prezentowane przypadki potwierdzają również hypogonadyzm hypogonadotropowy jako cechę tego zespołu.

Introduction: diabetes is a common disease with a steadily increasing prevalence. It predisposes to cardiovascular diseases including myocardial infarction. The aim of the study is to analyse the impact of diabetes on clinical presentation, management and prognosis on patients with myocardial infarction in a modern therapeutic context. Methods: the data were collected from the national multicentric registry (Fast-MI 2010) which included 4169 consecutive patients admitted for myocardial infarction in october 2010 and with a clinical follow-up of 36 months. Results: diabetes was found at admission in 835 patients (20.0%) of the cohort of whom 236 patients (5.7%) were treated with insulin. These patients are older (70.1 vs. 63.3 years, p

Background: The association between the orosensory detection of lipids, preference for fatty foods, and body mass index (BMI; in kg/m 2 ) is controversial in humans. Objective: We explored the oral lipid-sensing system and the orosensory-induced autonomic reflex system in lean and obese subjects. Design: Lean (BMI: 19 to ,25; n = 30) and obese (BMI .30; n = 29) age-matched men were enrolled. Their oral threshold sensitivity to linoleic acid (LA) was determined by using a 3-alternative forced-choice ascending procedure, and their eating habits were established by the analysis of 4 consecutive 24-h food-consumption diaries. The effect of brief oral lipid stimulations on plasma triglyceride [(TG)pl] concentrations was analyzed in overnight-fasted lean and obese individuals subjected to a whole-mouth stimulation (sipand-spit procedure) with a control or 1% LA emulsions for 5 min according to a within-subject randomized design. Results: A large distribution of LA detection was shown in both groups. Mean detection thresholds were 0.053% (wt:wt) and 0.071% (wt:wt) in lean and obese subjects, respectively. No relation between the LA detection threshold and BMI was observed. The 5 subjects who detected only the higher concentration of LA (5% wt: wt) or were unable to distinguish properly between control and LA emulsions were obese. An analysis of dietary habits showed that these obese LA nontasters consumed more lipids and energy than did all other subjects. Brief whole-mouth stimulations (sip-and-spit procedure) with a control or 1% LA emulsion revealed an LAmediated rise in (TG)pl concentrations in overnight-fasted, lean subjects. The origin of this change seemed to be hepatic. This (TG)pl upregulation was not shown in obese subjects, which suggested that obesity led to disturbances in the oral-brainstem-periphery loop. Conclusion: Altogether, these data strongly suggest that obesity may interfere with the orosensory system responsible for the detection of free long-chain fatty acids in humans. This trial was registered at clinicaltrials.gov as NCT02028975. Am J Clin Nutr doi: 10. 3945/ajcn.113.077198.

Aims To evaluate if a single inpatient education training programme can achieve individualized therapeutic targets. Methods Patients with Type 1 diabetes participating in a flexible intensive therapy programme were consecutively included in a prospective monocentric study. They all participated in the same education programme which had a patient-centred approach. Before the intervention, patients were divided into three groups according to their main therapeutic target: Group 1, to decrease HbA1c concentration in patients with baseline HbA1c ≥ 58 mmol/mol (7.5%); Group 2, to improve quality of life and satisfaction with treatment in patients with baseline HbA1c < 58 mmol/mol (7.5%); and Group 3, to decrease the frequency of hypoglycaemic episodes in patients with severe or frequent hypoglycaemic episodes. Therapeutic targets were evaluated at 12 months. Quality of life and treatment satisfaction were evaluated with validated questionnaires completed at baseline and 6 months. Results In Group 1 (n = 74), the mean ± sd HbA1c concentration decreased from 75 ± 15 mmol/mol (9.0 ±1.4%) to 68 ±15 mmol/mol (8.4 ± 1.4%; P < 0.001), with 53% of patients experiencing a decrease in HbA1c concentration of at least 6 mmol/mol (0.5%), without weight gain or more frequent hypoglycaemia. In Group 2 (n = 12), patient satisfaction with treatment improved significantly (P < 0.0001). In Group 3 (n = 35), minor hypoglycaemia significantly decreased from a mean ± sd of 6.6 ± 4.7 to 3.2 ± 3.0 hypoglycaemic episodes/week (P < 0.001) and the incidence of severe hypoglycaemia dropped significantly from a mean ± sd of 2.31 ± 3.07 to 0.86 ± 2.46 episodes/patient/year (P < 0.001). Conclusions Many patients with different needs, who attended the same flexible intensive therapy education programme, which had a patient-centred approach, were able to achieve their individual therapeutic targets.

International audience; The nuclear receptor peroxisome proliferator-activated receptor (PPAR) is a transcription factor whose expression is induced during adipogenesis and that is required for the acquisition and control of mature adipocyte functions. Indeed, PPAR induces the expression of genes involved in lipid synthesis and storage through enhancers activated during adipocyte differentiation. Here, we show that PPAR also binds to enhancers already active in preadipocytes as evidenced by an active chromatin state including lower DNA methylation levels despite higher CpG content. These constitutive enhancers are linked to genes involved in the insulin/insulin-like growth factor signaling pathway that are transcriptionally induced during adipogenesis but to a lower extent than lipid metabolism genes, because of stronger basal expression levels in preadipocytes. This is consistent with the sequential involvement of hormonal sensitivity and lipid handling during adipocyte maturation and correlates with the chromatin structure dynamics at constitutive and activated enhancers. Interestingly, constitutive enhancers are evolutionary conserved and can be activated in other tissues, in contrast to enhancers controlling lipid handling genes whose activation is more restricted to adipocytes. Thus, PPAR utilizes both broadly active and cell type-specific enhancers to modulate the dynamic range of activation of genes involved in the adipogenic process.

International audience; Objectives. Although a relationship between obesity and metabolic consequences with thyroid function has been reported, the underlying pathogenesis is not completely known. In the current study, we evaluated the thyroid function in obese and/or diabetic patients compared to healthy normal weight peers, exploring the possible association between components of metabolic syndrome and thyroid function parameters. Methods. We recruited 108 subjects (56 male and 52 female). In all subjects, thyroid stimulating hormone (TSH), free thyroxine (FT4), fasting plasma levels of insulin and glucose, homeostasis model assessment for insulin resistance, and obesity parameters were assessed. Results. We found that circulating levels of TSH and FT4 were significantly increased in overweight and obese subjects. However, the data do not reveal any change of these hormones in diabetics. Multivariate linear regression analysis showed that TSH was directly associated with both obesity and insulin resistance parameters (p < 0.05). FT4 was negatively associated only with obesity parameters (p < 0.05). Conclusions. Our data strongly support that the changes of thyroid hormones may be influenced by adiposity and its metabolic consequences, such as insulin resistance. This relationship can be explained by a cross talk between adipose tissue release and thyroid function. Nevertheless, metformin treatment seems to affect thyroid function in diabetic patients by maintaining plasma thyrotropin levels to subnormal levels.

International audience; The role of the gut microbiota in the induction of metabolic diseases has now been increasingly recognized worldwide. Indeed, a specific gut microbiota has been shown to characterize lean versus obese phenotypes both in humans and mice. We have also recently demonstrated that a precise gut microbiota is associated with the host's responsiveness to a high-fat diet. Therefore, we hypothesized that insulin resistance in humans could also be linked to a specific gut microbiota. To this aim, microbial DNA and RNA were extracted from the appendix contents of insulin-resistant versus insulin-sensitive obese subjects, matched for body mass index and age, and analyzed by DNA- and RNA-DGGE. Microbial DNA analysis showed that the patients fully segregated according to their degree of insulin action. Conversely, microbial RNA investigation showed that some degree of homology still existed between insulin-sensitive and insulin-resistant patients. Quantitative trait analysis, ordinary least squares regression, principal components regression, partial least squares, canonical correlation analysis, and canonical correspondence analysis also showed a net separation of the two phenotypes analyzed. We conclude that a specific gut microbial profile is associated with insulin action in humans.

International audience; BACKGROUND: Phthalic acid esters are widely used in the manufacture of plastics. Numerous studies have shown that these phthalates impair testicular testosterone production in the rat. However, the scarce and contradictory data concerning humans have cast doubt over whether these compounds are also anti-androgenic in man. We therefore investigated the direct effects of di-(2-ethylhexyl) phthalate (DEHP) and mono-(2-ethylhexyl) phthalate (MEHP) on organo-cultured adult human testis and a human cell line. METHODS: Adult human testis explants or NCI-H295R adrenocortical human cells were cultured with DEHP or MEHP. The effects of ketoconazole, used as a reference molecule, were also assessed. RESULTS: In both models, DEHP and MEHP significantly inhibited testosterone production. The effects of both phthalates appeared to be specific for steroidogenesis, as INSL3 production by Leydig cells was not altered. Furthermore, the phthalates of interest had no effect on inhibin B production by Sertoli cells or on germ cell apoptosis. As only a small fraction of the phthalates added was found in the testis explants, and as these compounds were found to be metabolized, we estimate that the anti-androgenic effects observed occurred at concentrations of phthalates that are of the same order of magnitude as exposures reported in the literature for men. CONCLUSIONS: We provide the first evidence that DEHP and MEHP can inhibit testosterone production in the adult human testis. This is consistent with recent epidemiological findings of an inverse correlation between exposure to MEHP and testosterone concentrations.

International audience; Endoplasmic reticulum (ER) stress is proposed as a novel link between elevated fatty acids levels, obesity and insulin resistance in liver and adipose tissue. However, it is unknown whether ER stress also contributes to lipid-induced insulin resistance in skeletal muscle, the major tissue responsible of insulin-stimulated glucose disposal. Here, we investigated the possible role of ER stress in palmitate-induced alterations of insulin action, both in vivo, in gastrocnemius of high-palm diet fed mice, and in vitro, in palmitate-treated C(2)C(12) myotubes. We demonstrated that 8 weeks of high-palm diet increased the expression of ER stress markers in muscle of mice, whereas ex-vivo insulin-stimulated PKB phosphorylation was not altered in this tissue. In addition, exposure of C(2)C(12) myotubes to either tuncamycine or palmitate induced ER stress and altered insulin-stimulated PKB phosphorylation. However, alleviation of ER stress by either TUDCA or 4-PBA treatments, or by overexpressing Grp78, did not restore palmitate-induced reduction of insulin-stimulated PKB phosphorylation in C(2)C(12) myotubes. This work highlights that, even ER stress is associated with palmitate-induced alterations of insulin signaling, ER stress is likely not the major culprit of this effect in myotubes, suggesting that the previously proposed link between ER stress and insulin resistance is less important in skeletal muscle than in adipose tissue and liver.

International audience; Inhibition of dipeptidyl peptidase-4 (DPP-4) activity improves glucose homeostasis through a mode of action related to the stabilization of the active forms of DPP-4-sensitive hormones such as the incretins that enhance glucose-induced insulin secretion. However, the DPP-4 enzyme is highly expressed on the surface of intestinal epithelial cells; hence, the role of intestinal vs. systemic DPP-4 remains unclear. To analyze mechanisms through which the DPP-4 inhibitor sitagliptin regulates glycemia in mice, we administered low oral doses of the DPP-4 inhibitor sitagliptin that selectively reduced DPP-4 activity in the intestine. Glp1r(-/-) and Gipr(-/-) mice were studied and glucagon-like peptide (GLP)-1 receptor (GLP-1R) signaling was blocked by an i.v. infusion of the corresponding receptor antagonist exendin (9-39). The role of the dipeptides His-Ala and Tyr-Ala as DPP-4-generated GLP-1 and glucose-dependent insulinotropic peptide (GIP) degradation products was studied in vivo and in vitro on isolated islets. We demonstrate that very low doses of oral sitagliptin improve glucose tolerance and plasma insulin levels with selective reduction of intestinal but not systemic DPP-4 activity. The glucoregulatory action of sitagliptin was associated with increased vagus nerve activity and was diminished in wild-type mice treated with the GLP-1R antagonist exendin (9-39) and in Glp1r(-/-) and Gipr(-/-) mice. Furthermore, the dipeptides liberated from GLP-1 (His-Ala) and GIP (Tyr-Ala) deteriorated glucose tolerance, reduced insulin, and increased portal glucagon levels. The predominant mechanism through which DPP-4 inhibitors regulate glycemia involves local inhibition of intestinal DPP-4 activity, activation of incretin receptors, reduced liberation of bioactive dipeptides, and activation of the gut-to-pancreas neural axis.

International audience; Over the past 2 years, more than 1300 manuscripts have been published on glucagon-like peptide-1 (GLP-1) and yet, what do we know about it for sure? The European Club for the Study of GLP-1 (EuCSGLP-1) has debated the latest controversies concerning GLP-1, including both fundamental and clinical aspects, and concluded that the control of glucose metabolism by GLP-1 requires paracrine activation of the enteric nervous system to regulate numerous physiological functions. This involves-but is not limited to-the endocrine pancreas, liver, cardiovascular system, gastric-emptying and the brain. For this reason, the role of GLP-1 as an endocrine hormone has come under question. As systemic concentration of the peptide was not thought to be relevant to its physiological action, it was proposed that dipeptidyl peptidase-4 (DPP4) inhibitors would involve the control of enteric, rather than circulating, DPP4 activity to effectively regulate glycaemia. In any case, the concomitant insulinotropic and glucagonostatic roles of GLP-1 were believed to be of equal importance to glucose control. Another important question was related to the role of GLP-1 on beta cell apoptosis, regeneration and differentiation in type 2 diabetic patients. Although evidence in vitro showed that GLP-1 controls these functions, such effects remain elusive in humans in vivo. Nevertheless, the consensus was that GLP-1 could control glucose responsiveness, one of the first impaired physiological functions at the onset of diabetes. The therapeutic efficiency of GLP-1 would be related to the initial restoration of glucose competence, while an increase of beta cell mass has not yet been demonstrated. From a clinical and fundamental point of view, it was concluded that, at the onset of diabetes, an initial triggering of GLP-1 secretion-by metformin coupled with a DPP4 inhibitor-would help to activate the gut-peripheral axis and, hence, restore adequate regulation of glycaemia. GLP-1 analogues would certainly be helpful in association with long-acting insulin (albeit off-label) in patients with impaired beta cells and GLP-1 secretory potential. However, a reliable and routine feasible test to systematically assess dynamic insulin secretion is essential. More important, factors that influence therapeutic response, such as compliance and lifestyle, as well as pharmacokinetics and dosing, disease duration, age, gender, ethnicity, patients' clinical characteristics, autonomic nervous system integrity and genotype characteristics also need to be considered. A few innovative perspectives have been debated, such as the recently discovered cardiovascular protective effects of the native GLP-1 peptide and its degradation product GLP-1(9-36), as well as the neuroprotection offered by GLP-1. Although still considered speculative, these perspectives remain hopeful and promising.

OBJECTIVE A strong association between genetic variants and obesity was found for the fat mass and obesity-associated gene (FTO). However, few details are known concerning the expression and function of FTO in skeletal muscle of patients with metabolic diseases. RESEARCH DESIGN AND METHODS We investigated basal FTO expression in skeletal muscle from obese nondiabetic subjects and type 1 and type 2 diabetic patients, compared with age-matched control subjects, and its regulation in vivo by insulin, glucose, or rosiglitazone. The function of FTO was further studied in myotubes by overexpression experiments. RESULTS We found a significant increase of FTO mRNA and protein levels in muscle from type 2 diabetic patients, whereas its expression was unchanged in obese or type 1 diabetic patients. Moreover, insulin or glucose infusion during specific clamps did not regulate FTO expression in skeletal muscle from control or type 2 diabetic patients. Interestingly, rosiglitazone treatment improved insulin sensitivity and reduced FTO expression in muscle from type 2 diabetic patients. In myotubes, adenoviral FTO overexpression increased basal protein kinase B phosphorylation, enhanced lipogenesis and oxidative stress, and reduced mitochondrial oxidative function, a cluster of metabolic defects associated with type 2 diabetes. CONCLUSIONS This study demonstrates increased FTO expression in skeletal muscle from type 2 diabetic patients, which can be normalized by thiazolidinedione treatment. Furthermore, in vitro data support a potential implication of FTO in oxidative metabolism, lipogenesis and oxidative stress in muscle, suggesting that it could be involved in the muscle defects that characterize type 2 diabetes.

International audience; Neurotensin (NT) is secreted from neurons and gastrointestinal endocrine cells. We previously reported that the three NT receptors (NTSRs) are expressed in pancreatic islets and beta cell lines on which we observed a protective effect of NT against cytotoxic agents. In this study, we explored the role of NT on insulin secretion in the endocrine pancreatic beta cells. We observed that NT stimulates insulin secretion at low glucose level and has a small inhibiting effect on stimulated insulin secretion from isolated islets or INS-1E cells. We studied the mechanisms by which NT elicited calcium concentration changes using fura-2 loaded islets or INS-1E cells. NT increases calcium influx through the opening of cationic channels. Similar calcium influxes were observed after treatment with NTSR selective ligands. NT-evoked calcium regulation involves PKC and the translocation of PKCalpha and PKCepsilon to the plasma membrane. Part of NT effects appears to be also mediated by PKA but not via the Erk pathway. Taken together, these data provide evidence for an important endocrine role of NT in the regulation of the secretory function of beta cells.

International audience; The aim of this study was to evaluate the relative contributions of various hormones involved in the regulation of lipid mobilization in subcutaneous adipose tissue (SCAT) during exercise and to assess the impact of obesity on this regulation. Eight lean and eight obese men performed a 60-min cycle exercise bout at 50% of their peak oxygen uptake on two occasions: during intravenous infusion of octreotide (a somatostatin analog) or physiological saline (control condition). Lipolysis in SCAT was evaluated using in situ microdialysis. One microdialysis probe was perfused with the adrenergic blockers phentolamine and propranolol while another probe was perfused with the phosphodiesterase and adenosine receptor inhibitor aminophylline. Compared with the control condition, infusion of octreotide reduced plasma insulin levels in lean (from approximately 3.5 to 0.5 microU/ml) and in obese (from approximately 9 to 2 microU/ml), blunted the exercise-induced rise in plasma GH and epinephrine levels in both groups, and enhanced the exercise-induced natriuretic peptide (NP) levels in lean but not in obese subjects. In both groups, octreotide infusion resulted in higher exercise-induced increases in dialysate glycerol concentrations in the phentolamine-containing probe while no difference in lipolytic response was found in the aminophylline-containing probe. The results suggest that insulin antilipolytic action plays a role in the regulation of lipolysis during exercise in lean as well as in obese subjects. The octreotide-induced enhancement of exercise lipolysis in lean subjects was associated with an increased exercise-induced plasma NP response. Adenosine may contribute to the inhibition of basal lipolysis in both subject groups.

International audience; AIM: Perioperative tight blood glucose (BG) control using insulin therapy after major surgery is a difficult, time-consuming task that also raises some concerns over the risk of severe hypoglycaemia. The aim of the present prospective study was to evaluate the efficacy and safety of an insulin therapy protocol in use at our institution. METHODS: A total of 230 consecutive patients (mean+/-SD age: 67+/-11 years; diabetic patients: n=62) undergoing cardiac surgery (coronary artery bypass grafting: n=137; 20% off-pump) or intrathoracic aortic (n=10) surgery were included. BG control was managed according to an insulin therapy protocol, described by Goldberg et al. (2004) [11], in use for 6 months in our intensive care unit. Insulin infusion rate and frequency of BG monitoring were both adjusted according to: (1) the current BG value; (2) the previous BG value; and (3) the current insulin infusion rate. Efficacy was assessed by the percentage of time spent at the target BG level (100-139 mg/dL) intraoperatively and during the first 2 postoperative days (POD). RESULTS: All patients received postoperative insulin therapy. Patients spent 57.3% and 69.7% of time within the BG target range on POD 1 and 2, respectively. The percentage of time was significantly higher in nondiabetics than in diabetics. Mean BG measurements per patient intraoperatively, on POD 1 and on POD 2 were 4+/-1, 10+/-2 and 7+/-2, respectively. No patient experienced any severe hypoglycaemic events (BG

International audience; AIMS/HYPOTHESIS: Risk factors for incident type 2 diabetes, in particular, hepatic markers, have rarely been studied in leaner individuals. We aimed to identify the metabolic and hepatic markers associated with incident diabetes in men and women with a BMI of or=27 kg/m(2). METHODS: Risk factors for 9 year incident diabetes were compared in the French Data from an Epidemiological Study on the Insulin Resistance Syndrome (DESIR) cohort. Comparisons were made between the 2,947 participants with a BMI of or=27 kg/m(2). RESULTS: There were 92 incident cases of diabetes in individuals with a BMI of or=27 kg/m(2). Among those who were not markedly overweight, classical biological markers were associated with 9 year incident diabetes, glycaemia being the strongest predictor. gamma-Glutamyltransferase (GGT), either considered as a continuous variable or at levels >or=20 U/l, was associated with incident diabetes, with a stronger effect in the BMI or=27 kg/m(2) (results after adjustment for alcohol intake, alanine aminotransferase, waist circumference and the HOMA insulin resistance index). CONCLUSIONS/INTERPRETATION: In individuals with a BMI of

OBJECTIVE Adipose tissue may contain few large adipocytes (hypertrophy) or many small adipocytes (hyperplasia). We investigated factors of putative importance for adipose tissue morphology. RESEARCH DESIGN AND METHODS Subcutaneous adipocyte size and total fat mass were compared in 764 subjects with BMI 18–60 kg/m2. A morphology value was defined as the difference between the measured adipocyte volume and the expected volume given by a curved-line fit for a given body fat mass and was related to insulin values. In 35 subjects, in vivo adipocyte turnover was measured by exploiting incorporation of atmospheric 14C into DNA. RESULTS Occurrence of hyperplasia (negative morphology value) or hypertrophy (positive morphology value) was independent of sex and body weight but correlated with fasting plasma insulin levels and insulin sensitivity, independent of adipocyte volume (β-coefficient = 0.3, P < 0.0001). Total adipocyte number and morphology were negatively related (r = −0.66); i.e., the total adipocyte number was greatest in pronounced hyperplasia and smallest in pronounced hypertrophy. The absolute number of new adipocytes generated each year was 70% lower (P < 0.001) in hypertrophy than in hyperplasia, and individual values for adipocyte generation and morphology were strongly related (r = 0.7, P < 0.001). The relative death rate (∼10% per year) or mean age of adipocytes (∼10 years) was not correlated with morphology. CONCLUSIONS Adipose tissue morphology correlates with insulin measures and is linked to the total adipocyte number independently of sex and body fat level. Low generation rates of adipocytes associate with adipose tissue hypertrophy, whereas high generation rates associate with adipose hyperplasia.

International audience; OBJECTIVE: To explore sex differences in the regulation of lipolysis during exercise, the lipid-mobilizing mechanisms in the subcutaneous adipose tissue (SCAT) of overweight men and women were studied using microdialysis. RESEARCH METHODS AND PROCEDURES: Subjects matched for age, BMI, and physical fitness performed two 30-minute exercise bouts in a randomized fashion: the first test at 30% and 50% of their individual maximal oxygen uptake (Vo(2max)) and the second test at 30% and 70% of their Vo(2max). RESULTS: In both groups, an exercise-dependent increment in extracellular glycerol concentration (EGC) was observed. Whatever the intensity, phentolamine [alpha-adrenergic receptor (AR) antagonist] added to a dialysis probe potentiated exercise-induced lipolysis only in men. In a probe containing phentolamine plus propranolol (beta-AR antagonist), no changes in EGC occurred when compared with the control probe when exercise was performed at 30% and 50% Vo(2max). A significant reduction of EGC (when compared with the control probe) was observed in women at 70% Vo(2max). At each exercise power, the plasma non-esterified fatty acid and glycerol concentrations were higher in women. Exercise-induced increase in plasma catecholamine levels was lower in women compared with men. Plasma insulin decreased and atrial natriuretic peptide increased similarly in both groups. DISCUSSION: Overweight women mobilize more lipids (assessed by glycerol) than men during exercise. alpha(2)-Anti-lipolytic effect was functional in SCAT of men only. The major finding is that during low-to-moderate exercise periods (30% and 50% Vo(2max)), lipid mobilization in SCAT relies less on catecholamine-dependent stimulation of beta-ARs than on an increase in plasma atrial natriuretic peptide concentrations and the decrease in plasma insulin.

We previously showed that pancreatic β-cells express neuronal nitric oxide synthase (nNOS) that controls insulin secretion through two catalytic activities: nitric oxide (NO) production and cytochrome c reductase activity. We now provide evidence that the endogenous protein inhibitor of nNOS (PIN) is expressed in rat pancreatic islets and INS-1 cells. Double-immunofluorescence studies showed a colocalization of PIN with both nNOS and myosin Va in insulin-secreting β-cells. Electron microscopy studies confirmed that PIN is mainly associated with insulin secretory granules and colocated with nNOS in the latter. In addition, PIN overexpression in INS-1 cells enhanced glucose-induced insulin secretion, which is only partly reversed by addition of an NO donor, sodium nitroprusside (SNP), and unaffected by the inhibitor of cytochrome c reductase activity, miconazole. In contrast, the pharmacological inhibitor of nNOS, Nω-nitro-l-arginine methyl ester, amplified glucose-induced insulin secretion, an effect insensitive to SNP but completely normalized by the addition of miconazole. Thus, PIN insulinotropic effect could be related to its colocalization with the actin-based molecular motor myosin Va and as such be implicated in the physiological regulation of glucose-induced insulin secretion at the level of the exocytotic machinery.

International audience; Serotonin (5-HT) transporter (SERT) regulates the level of 5-HT in placenta. Initially, we found that in gestational diabetes mellitus (GDM), whereas free plasma 5-HT levels were elevated, the 5-HT uptake rates of trophoblast were significantly down-regulated, due to impairment in the translocation of SERT molecules to the cell surface. We sought to determine the factors mediating the down-regulation of SERT in GDM trophoblast. We previously reported that an endoplasmic reticulum chaperone, ERp44, binds to Cys200 and Cys209 residues of SERT to build a disulfide bond. Following this posttranslational modification, before trafficking to the plasma membrane, SERT must be dissociated from ERp44; and this process is facilitated by insulin signaling and reversed by the insulin receptor blocker AGL2263. However, the GDM-associated defect in insulin signaling hampers the dissociation of ERp44 from SERT. Furthermore, whereas ERp44 constitutively occupies Cys200/Cys209 residues, one of the SERT glycosylation sites, Asp208 located between the two Cys residues, cannot undergo proper glycosylation, which plays an important role in the uptake efficiency of SERT. Herein, we show that the decrease in 5-HT uptake rates of GDM trophoblast is the consequence of defective insulin signaling, which entraps SERT with ERp44 and impairs its glycosylation. In this regard, restoring the normal expression of SERT on the trophoblast surface may represent a novel approach to alleviating some GDM-associated complications.

β3-Adrenoceptors promote glucose uptake in brown adipose tissue via both cAMP-mediated increases in GLUT1 transcription and mTORC2-stimulated translocation of newly synthesized GLUT1 to the plasma membrane., Brown adipose tissue is the primary site for thermogenesis and can consume, in addition to free fatty acids, a very high amount of glucose from the blood, which can both acutely and chronically affect glucose homeostasis. Here, we show that mechanistic target of rapamycin (mTOR) complex 2 has a novel role in β3-adrenoceptor–stimulated glucose uptake in brown adipose tissue. We show that β3-adrenoceptors stimulate glucose uptake in brown adipose tissue via a signaling pathway that is comprised of two different parts: one part dependent on cAMP-mediated increases in GLUT1 transcription and de novo synthesis of GLUT1 and another part dependent on mTOR complex 2–stimulated translocation of newly synthesized GLUT1 to the plasma membrane, leading to increased glucose uptake. Both parts are essential for β3-adrenoceptor–stimulated glucose uptake. Importantly, the effect of β3-adrenoceptor on mTOR complex 2 is independent of the classical insulin–phosphoinositide 3-kinase–Akt pathway, highlighting a novel mechanism of mTOR complex 2 activation.

International audience; BACKGROUND: How weight change affects the metabolic syndrome (MS) and its parameters is unknown, particularly, in a leaner European population such as the French prospective D.E.S.I.R. cohort. METHODS: In 3770 D.E.S.I.R. participants (sex ratio=1) averaging 47.5 years (range 30-64), with measured weight and MS parameters at baseline (D0) and at 6 year follow-up (D6), we assessed this relationship across five weight-change classes, using stable weight as the referent group (-2 to +2 kg). We used analysis-of-covariance to assess changes in each MS parameter and logistic regression to assess incident MS, according to the National Cholesterol Education Program (NCEP). We also assessed weight-change effect on MS status between D0 and D6. RESULTS: At D0, average weight was 68.4 kg (SD 12.3); BMI was 24.8 kg/m2 (SD 3.5). From D0-D6, the cohort gained a mean 2.1 kg (median 2.0; SD 4.4). After adjustment for age and D0 weight, there was a strong linear relationship with weight change and worsening of the following MS parameters at D6: fasting insulin, waist girth, fasting glucose, fasting triglycerides, HDL cholesterol, and systolic and diastolic blood pressure (P9 kg; 10% of those who lost >2 kg reverted to non-NCEP-MS. CONCLUSIONS: All continuous MS measures are linearly related to weight change, and MS can resolve with modest weight loss, underscoring the importance of maintaining lifelong normal weight.

The results presented herein demonstrate that apelin is expressed and secreted by both human and mouse adipocytes. Apelin mRNA levels in isolated adipocytes are close to other cell types present in white adipose tissue or other organs known to express apelin such as kidney, heart, and to a lesser extent brown adipose tissue. Apelin expression is increased during adipocyte differentiation stage. A comparison of four different models of obesity in mice showed a large increase in both apelin expression in fat cells and apelin plasma levels in all the hyperinsulinemia-associated obesities and clearly demonstrated that obesity or high-fat feeding are not the main determinants of the rise of apelin expression. The lack of insulin in streptozotocin-treated mice is associated with a decreased expression of apelin in adipocytes. Furthermore, apelin expression in fat cells is strongly inhibited by fasting and recovered after refeeding, in a similar way to insulin. A direct regulation of apelin expression by insulin is observed in both human and mouse adipocytes and clearly associated with the stimulation of phosphatidylinositol 3-kinase, protein kinase C, and MAPK. These data provide evidence that insulin exerts a direct control on apelin gene expression in adipocytes. In obese patients, both plasma apelin and insulin levels were significantly higher, suggesting that the regulation of apelin by insulin could influence blood concentrations of apelin. The present work identifies apelin as a novel adipocyte endocrine secretion and focuses on its potential link with obesity-associated variations of insulin sensitivity status.

International audience; The Drosophila miRNA-encoding gene bantam controls cell and tissue growth. A new study now reveals that a large part of its effects on growth could come from its inhibition of the production of the molting hormone ecdysone.

International audience; The beta-amyloid (Abeta) peptide Abeta25-35 provokes apoptosis of cerebellar granule cells through activation of caspase-3 while the neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) promotes granule cell survival by inhibiting caspase-3 activation through the intrinsic apoptotic pathway. The aim of the present study was to determine whether PACAP could prevent Abeta25-35 neurotoxicity by inhibiting caspase-3 activity. A 24-h exposure of cultured cerebellar granule cells to Abeta25-35 induced shrinkage of cell bodies, neurite retraction and alteration of mitochondrial activity. Administration of graded concentrations (10-80 microM) of Abeta25-35 induced a dose-related decrease of the number of living cells, and the neurotoxic effect was highly significant after a 24-h exposure to 80 microM Abeta25-35. Exposure of cerebellar granule cells to Abeta25-35 markedly enhanced caspase-3 but not caspase-9 activity. Co-incubation with 1 microM PACAP significantly reduced Abeta25-35-evoked caspase-3 activation. In contrast, PACAP did not prevent the deleterious effects of Abeta25-35 on mitochondrial potential and granule cell survival. Taken together, these data suggest that caspase-3 activation is not the main pathway activated by Abeta25-35 that leads to granule cell death. The results also demonstrate that PACAP cannot be considered as a potent neuroprotective factor against Abeta25-35-induced apoptosis in cerebellar granule neurons.

International audience; OBJECTIVE:Previous work from our laboratory has demonstrated that frog urotensin-II (UII), at a high concentration, inhibits glucose-induced insulin release in the rat pancreas. We have investigated the effect of rat UII and two structural analogs on insulin secretion and searched for the presence of UII-immunoreactivity in rat pancreatic extracts.METHODS:The study was performed in the perfused rat pancreas. UII as well as its analogs were synthesized by solid phase methodology. Pancreatic extracts were analyzed for UII by reversed-phase HPLC combined with a sensitive UII RIA.RESULTS:Infusion of synthetic rat UII inhibited glucose-induced insulin release in a dose-dependent manner (IC(50): 0.12 nmol/l). UII (1 nmol/l) also inhibited the insulin responses induced by carbachol, glucagon-like peptide-1, and a calcium channel agonist (BAY K 8644). The inhibitory effect of UII was mimicked by the potent G protein-coupled receptor (GPR14) agonist [3-iodo-Tyr(6)]UII(4-11). In contrast, [Ala(8)]UII(4-11), a UII analog devoid of contractile activity on rat aortic rings, did not affect glucose-induced insulin secretion. Analysis of rat pancreatic extracts revealed the presence of an immunoreactive peptide exhibiting the same retention time as synthetic rat UII.CONCLUSIONS:Our results demonstrate that UII is a potent insulinostatic peptide. The observation that UII is actually present in the pancreas suggests that this peptide may play a physiological role in the control of insulin secretion. Concerning the two UII analogs tested, only [3-iodo-Tyr(6)]UII(4-11), reportedly possessing GPR14-mediated contractile activity, mimics the insulinostatic effect of UII. This finding would support the view that UII acts on the pancreatic beta cell through the GPR14 receptor.

International audience; ID-1101 (4-hydroxyisoleucine), an amino acid extracted from fenugreek seeds, exhibits an interesting glucose-dependent insulin-stimulating activity. The present study was undertaken to investigate a possible extrapancreatic effect of ID-1101 on insulin signaling and action besides its previously described insulinotropic action. Insulin-sensitizing effects of ID-1101 were investigated in rat in vivo by three different approaches: 1) using euglycemic hyperinsulinemic clamps in two different rat models of insulin resistance, i.e., Zucker fa/fa rats and rats fed a sucrose-lipid diet; 2) measuring liver and muscle phosphatidylinositol (PI) 3-kinase activity after an acute injection of ID-1101 in normal and insulin-resistant diabetic rats; and 3) after chronic treatment in two rat models of insulin resistance. Euglycemic hyperinsulinemic clamp experiments revealed that ID-1101 can improve insulin resistance through an increase of peripheral glucose utilization rate in sucrose-lipid-fed rats and by decreasing hepatic glucose production in Zucker fa/fa rats. Moreover, we demonstrated that a single injection of ID-1101 activates the PI 3-kinase activity in liver and muscle from normal rats but also in muscle from diabetic rats. Finally, chronic ID-1101 treatment significantly reduced insulinemia in type 2 diabetic rats and reduced the progression of hyperinsulinemia in insulin-resistant obese Zucker fa/fa rats. These findings clearly demonstrate that ID-1101 can reduce insulin resistance through activation of the early steps of insulin signaling in peripheral tissues and in liver. In summary, ID-1101, besides its insulinotropic effect, directly improves insulin sensitivity, making it a potentially very valuable therapeutic agent for diabetes treatment.

NCB5OR is a highly conserved NAD(P)H reductase that contains a cytochrome b5-like domain at the N terminus and a cytochrome b5 reductase-like domain at the C terminus. The enzyme is located in the endoplasmic reticulum (ER) and is widely expressed in organs and tissues. Targeted inactivation of this gene in mice has no impact on embryonic or fetal viability. At 4 weeks of age, Ncb5or -/- mice have normal blood glucose levels but impaired glucose tolerance. Isolated Ncb5or -/- islets have markedly impaired glucose- or arginine-stimulated insulin secretion. By 7 weeks of age, these mice develop severe hyperglycemia with markedly decreased serum insulin levels and nearly normal insulin tolerance. As the animals age, there is a progressive loss of beta cells in pancreatic islets, but there is no loss of alpha, delta, or PP cells. Electron microscopy reveals degranulation of beta cells and hypertrophic and hyperplastic mitochondria, some of which contain electron dense inclusions. Four-week-old Ncb5or -/- mice have enhanced sensitivity to the diabetogenic agent streptozotocin. NCB5OR appears to play a critical role in protecting pancreatic beta cells against oxidant stress.

Chicken muscle ribosomal protein S6 kinase (S6K1) has been recently characterised and its enzymic activity is regulated by the nutritional and hormonal (insulin) status in vivo. The regulation of S6K1 is still unknown in neonatal chicks. The present study aimed to compare the activation of S6K1 in early-feeding (EF) and 48 h-delayed-feeding (DF) chicks from hatching to 4 d of age. During post-hatching starvation, S6K1 activity remained at the basal level measured in the control-hatched chicks. The maximum S6K1 activity was recorded on the first day of feeding with an increase of about 2·5-fold in the EF and DF chicks (P

International audience; In chickens, leptin is expressed mainly in the liver, where its receptor gene expression has also been reported, and in adipose tissue. In view of the key role played by the liver in lipogenesis in avian species, the hepatic expression of leptin may have physiological significance. In this study, we showed that leptin is constitutively expressed and secreted in a chicken-derived hepatoma cell line (LMH). Although insulin regulates leptin expression in vivo, incubation of LMH cells in the presence of 100 nM insulin for 24 or 48 h had no effect on leptin expression or its secretion in the culture medium. In addition, we developed a specific chicken leptin receptor real-time reverse transcription (RT)-PCR, and downregulation of leptin receptor gene expression by homologous and heterologous signals was demonstrated, as relative leptin receptor mRNA levels were significantly decreased after exposure of LMH cells to recombinant chicken leptin or porcine insulin. In conclusion, our results indicate that leptin is probably able to desensitize its own response in the chicken liver. Finally, the ability of insulin and leptin to regulate chicken leptin receptor gene expression suggests a direct role of leptin in the control of hepatic metabolism.

International audience; So far, there has been no evidence for any direct pancreatic effect of leptin in the chicken. The present study was aimed at detecting chicken leptin receptor (cOb-R) expression in isolated chicken islets of Langerhans and to examine the direct effect of leptin on insulin secretion after stimulation by acetylcholine (1 micro M) + glucose (14 mM) from isolated perfused chicken pancreas. We will show that i) full length cOb-R mRNA was expressed in isolated pancreatic islets of chickens, ii) recombinant chicken leptin (10 nM) or diazoxide (100 micro M) rapidly (within 2 min) and significantly suppressed insulin secretion induced by acetylcholine stimulation without any change in volume outflow rate, iii) tolbutamide (100 micro M) introduced 10 min after leptin and perfused for 10 min fully reversed the suppressive effect of leptin on pre-established acetylcholine-induced insulin release. In conclusion, we found that leptin has a profound inhibitory influence upon insulin secretion in perfused chicken pancreas. The results suggest that leptin inhibits insulin secretion by acting before or at the level of K ATP channels in chicken pancreatic beta-cells. Further studies are warranted to clarify the specific inhibitory mechanism.

Ghrelin is a recently recognized gut-brain peptide originally derived from the gastric mucosa. It stimulates growth hormone release, increases appetite and facilitates fat storage, and may interact with glucose metabolism. We studied the ghrelin gene in a group of 70 tall and obese children (mean age 9.4 year, Z body mass index [BMI] and Z height >3 and/or BMI percentile >99%). We found 10 single nucleotide polymorphisms. One common polymorphism of the ghrelin gene, which corresponds to an amino acid change in the tail of the prepro-ghrelin molecule, was significantly associated with children with a higher BMI (P = 0.001), and with lower insulin secretion during the first part of an oral glucose tolerance test (P = 0.05) although no difference in glucose levels was noted. This might suggest increased insulin sensitivity, although this is not supported by the lack of difference in fasting and 2 hour insulin levels; alternatively, this may be indicative of impaired first phase insulin secretion. These data suggest that variations in the ghrelin gene contribute to obesity in children and may modulate glucose-induced insulin secretion.

International audience; Early in life, leptin plays a crucial role in hypothalamic neural organization. Leptin, most likely, controls neural gene expression conferring then specific phenotype regarding energy homeostasis. MicroRNAs are new regulators for several physiological functions, including the regulation of metabolism. However, the impact of leptin on hypothalamic microRNA patterns remains unknown. Here, we demonstrate that miR-200a, miR-200b and miR-429 are up-regulated in the hypothalamus of genetically obese and leptin deficient ob/ob mice. Leptin treatment down-regulates these miRNAs in ob/ob hypothalamus. The hypothalamic silencing of miR-200a increased the expression level of leptin receptor and insulin receptor substrate 2, reduced body weight gain, and restored liver insulin responsiveness. In addition, the overexpression of pre-miR-200a in a human neuroblastoma cell line impaired insulin and leptin signaling. These findings link the alteration of leptin and insulin signaling to the up-regulation of hypothalamic miR-200a which could be a new target for treatment of obesity.

International audience; The nuclear receptor peroxisome proliferator-activated receptor (PPAR) is a transcription factor whose expression is induced during adipogenesis and that is required for the acquisition and control of mature adipocyte functions. Indeed, PPAR induces the expression of genes involved in lipid synthesis and storage through enhancers activated during adipocyte differentiation. Here, we show that PPAR also binds to enhancers already active in preadipocytes as evidenced by an active chromatin state including lower DNA methylation levels despite higher CpG content. These constitutive enhancers are linked to genes involved in the insulin/insulin-like growth factor signaling pathway that are transcriptionally induced during adipogenesis but to a lower extent than lipid metabolism genes, because of stronger basal expression levels in preadipocytes. This is consistent with the sequential involvement of hormonal sensitivity and lipid handling during adipocyte maturation and correlates with the chromatin structure dynamics at constitutive and activated enhancers. Interestingly, constitutive enhancers are evolutionary conserved and can be activated in other tissues, in contrast to enhancers controlling lipid handling genes whose activation is more restricted to adipocytes. Thus, PPAR utilizes both broadly active and cell type-specific enhancers to modulate the dynamic range of activation of genes involved in the adipogenic process.

International audience; Nicotinic acetylcholine receptors (nAChRs) are pentameric ligand-gated cation channels well characterized in neuronal signal transmission. Moreover, recent studies have revealed nAChR expression in nonneuronal cell types throughout the body, including tissues involved in metabolism. In the present study, we screen gene expression of nAChR subunits in pancreatic islets and adipose tissues. Mice pancreatic islets present predominant expression of α7 and β2 nAChR subunits but at a lower level than in central structures. Characterization of glucose and energy homeostasis in α7β2nAChR(-/-) mice revealed no major defect in insulin secretion and sensitivity but decreased glycemia apparently unrelated to gluconeogenesis or glycogenolysis. α7β2nAChR(-/-) mice presented an increase in lean and bone body mass and a decrease in fat storage with normal body weight. These observations were associated with elevated spontaneous physical activity in α7β2nAChR(-/-) mice, mainly due to elevation in fine vertical (rearing) activity while their horizontal (ambulatory) activity remained unchanged. In contrast to α7nAChR(-/-) mice presenting glucose intolerance and insulin resistance associated to excessive inflammation of adipose tissue, the present metabolic phenotyping of α7β2nAChR(-/-) mice revealed a metabolic improvement possibly linked to the increase in spontaneous physical activity related to central β2nAChR deficiency.

Effects of insulin on the expression of liver-specific genes are part of the adaptive mechanisms aimed at maintaining energy homeostasis in mammals. When the diet is rich in carbohydrates, secreted insulin stimulates the expression of genes for enzymes involved in glucose utilization (glucokinase, L-type pyruvate kinase and lipogenic enzymes) and inhibits genes for enzymes involved in glucose production (phosphenolpyruvate carboxykinase). The mechanisms by which insulin controls the expression of these genes have been poorly understood. Recently, the transcription factor sterol-regulatory-element-binding protein 1c has been proposed as a key mediator of insulin transcriptional effects. Here we review the evidence that has led to this proposal and the consequences for our understanding of insulin effects in physiological or pathological conditions.

Hyperinsulinemia increases lactate release by various organs and tissues. Whereas it has been shown that aerobic glycolysis is linked to Na+-K+-ATPase activity, we hypothesized that stimulation by insulin of skeletal muscle Na+-K+-ATPase is responsible for increased muscle lactate production. To test this hypothesis, we assessed muscle lactate release in healthy volunteers from the [13C]lactate concentration in the effluent dialysates of microdialysis probes inserted into the tibialis anterior muscles on both sides and infused with solutions containing 5 mmol/l [U-13C]glucose. On one side, the microdialysis probe was intermittently infused with the same solution additioned with 2.10−5M ouabain. In the basal state, [13C]lactate concentration in the dialysate was not affected by ouabain. During a euglycemic-hyperinsulinemic clamp, [13C]lactate concentration increased by 135% in the dialysate without ouabain, and this stimulation was nearly entirely reversed by ouabain (56% inhibition compared with values in the dialysate collected from the contralateral probe). These data indicate that insulin stimulates muscle lactate release by activating Na+-K+-ATPase in healthy humans.

International audience; no Abstract available

International audience; The beneficial metabolic actions of estrogen-based therapies are mainly mediated by estrogen receptor α (ERα), a nuclear receptor that regulates gene transcription through two activation functions (AFs): AF-1 and AF-2. Using mouse models deleted electively for ERαAF-1 (ERαAF-1°) or ERαAF-2 (ERαAF-2°), we determined their respective roles in the actions of estrogens on body composition and glucose homeostasis in response to either a normal diet or a high-fat diet (HFD). ERαAF-2° males and females developed accelerated weight gain, massive adiposity, severe insulin resistance, and glucose intolerance--quite reminiscent of the phenotype observed in mice deleted for the entire ERα protein (ERα(-/-)). In striking contrast, ERαAF-1° and wild-type (wt) mice shared a similar metabolic phenotype. Accordingly, 17β-estradiol administration regulated key metabolic genes in insulin-sensitive tissues and conferred a strong protection against HFD-induced metabolic disturbances in wt and ERαAF-1° ovariectomized mice, whereas these actions were totally abrogated in ERαAF-2° and ERα(-/-) mice. Thus, whereas both AFs have been previously shown to contribute to endometrial and breast cancer cell proliferation, the protective effect of estrogens against obesity and insulin resistance depends on ERαAF-2 but not ERαAF-1, thereby delineating new options for selective modulation of ERα.

International audience; Hypoxia is well known to affect carbohydrate metabolism through its action on liver function and thus on glucose homeostasis. The aim of this study was to examine the carbohydrate, lipid and protein metabolic responses to 48 h of hypoxia, as well as the hormonal adaptations using both normoxic controls and hypoxic animals in the fasted state to standardize for the marked hypophagia observed in response to hypoxia. Hypoxia exposure (inspiratory oxygen fraction (FI,O2) = 0.1) resulted in a greater weight loss (-23 +/- 3.6% versus -16 +/- 2% in controls, p

Elevated expression/activity of adipose triglyceride lipase (ATGL) and/or reduced activity of hormone-sensitive lipase (HSL) in skeletal muscle are causally linked to insulin resistance in vitro. We investigated here the effect of high-fat feeding on skeletal muscle lipolytic proteins, lipotoxicity, and insulin signaling in vivo. Five-week-old C3H mice were fed normal chow diet (NCD) or 45% kcal high-fat diet (HFD) for 4 weeks. Wild-type and HSL knockout mice fed NCD were also studied. Whole-body and muscle insulin sensitivity, as well as lipolytic protein expression, lipid levels, and insulin signaling in skeletal muscle, were measured. HFD induced whole-body insulin resistance and glucose intolerance and reduced skeletal muscle glucose uptake compared with NCD. HFD increased skeletal muscle total diacylglycerol (DAG) content, protein kinase Cθ and protein kinase Cϵ membrane translocation, and impaired insulin signaling as reflected by a robust increase of basal Ser1101 insulin receptor substrate 1 phosphorylation (2.8-fold, P < .05) and a decrease of insulin-stimulated v-Akt murine thymoma viral oncogene homolog Ser473 (−37%, P < .05) and AS160 Thr642 (−47%, P