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Background and Purpose Cerebral organoids (COs) have been used for studying brain development, neural disorders, and species‐specific drug pharmacology and toxicology, but the potential of COs transplantation therapy for brain injury remains to be answered. Methods With preparation of traumatic brain injury (TBI) model of motor dysfunction, COs at 55 and 85 days (55 and 85 d‐CO) were transplanted into damaged motor cortex separately to identify better transplantation donor for brain injury. Further, the feasibility, effectiveness, and underlying mechanism of COs transplantation therapy for brain injury were explored. Results 55 d‐CO was demonstrated as better transplantation donor than 85 d‐CO, evidenced by more neurogenesis and higher cell survival rate without aggravating apoptosis and inflammation after transplantation into damaged motor cortex. Cells from transplanted COs had the potential of multilinage differentiation to mimic in‐vivo brain cortical development, support region‐specific reconstruction of damaged motor cortex, form neurotransmitter‐related neurons, and migrate into different brain regions along corpus callosum. Moreover, COs transplantation upregulated hippocampal neural connection proteins and neurotrophic factors. Notably, COs transplantation improved neurological motor function and reduced brain damage. Conclusions This study revealed 55 d‐CO as better transplantation donor and demonstrated the feasibility and efficacy of COs transplantation in TBI, hoping to provide first‐hand preclinical evidence of COs transplantation for brain injury.

Metrnl is a newly identified secreted protein highly expressed in the intestinal epithelium. This study aimed to explore the role and mechanism of intestinal epithelial Metrnl in ulcerative colitis. Metrnl−/− (intestinal epithelial cell-specific Metrnl knockout) mice did not display any phenotypes of colitis under basal conditions. However, under administration of 3% dextran sodium sulfate (DSS) drinking water, colitis was more severe in Metrnl−/− mice than in WT mice, as indicated by comparisons of body weight loss, the presence of occult or gross blood per rectum, stool consistency, shrinkage in the colon, intestinal damage, and serum levels of inflammatory factors. DSS-induced colitis activated autophagy in the colon. This activation was partially inhibited by intestinal epithelial Metrnl deficiency, as indicated by a decrease in Beclin-1 and LC3-II/I and an increase in p62 in DSS-treated Metrnl−/− mice compared with WT mice. These phenomena were further confirmed by observation of autophagosomes and immunofluorescence staining for LC3 in epithelial cells. The autophagy-related AMPK-mTOR-p70S6K pathway was also activated in DSS-induced colitis, and this pathway was partially blocked by intestinal epithelial Metrnl deficiency, as indicated by a decrease in AMPK phosphorylation and an increase in mTOR and p70S6K phosphorylation in DSS-treated Metrnl−/− mice compared with WT mice. Therefore, Metrnl deficiency deteriorated ulcerative colitis at least partially through inhibition of autophagy via the AMPK-mTOR-p70S6K pathway, suggesting that Metrnl is a therapeutic target for ulcerative colitis.

Stroke is the second leading cause of death and main cause of disability worldwide, but with few effective therapies. Although stem cell-based therapy has been proposed as an exciting regenerative medicine strategy for brain injury, there are limitations. The developed cerebral organoids (COs) represent a promising transplantation source for stroke that remains to be answered. Here, we transplanted COs at 55 days and explored the feasibility in the rat middle cerebral artery occlusion (MCAO) model of stroke. COs transplantation at 6 h or even 24 h after MCAO significantly reduces brain infarct volume and improves neurological motor function. Transplanted COs show the potential of multilineage differentiation to mimic in vivo cortical development, support motor cortex region-specific reconstruction, form neurotransmitter-related neurons, and achieve synaptic connection with host brain via in situ differentiation and cell replacement in stroke. Cells from transplanted COs show extensive migration into different brain regions along corpus callosum. The mechanisms underlying COs transplantation therapy are also associated with enhanced neurogenesis, synaptic reconstruction, axonal regeneration and angiogenesis, and decreased neural apoptosis with more survival neurons after stroke. Moreover, COs transplantation promotes predominantly exogenous neurogenesis in the transplantation periphery of ipsilateral cortex and predominantly endogenous neurogenesis in the hippocampus and subventricular zone. Together, we demonstrate the efficacy and underlying mechanisms of COs transplantation in stroke. This preliminary but promising study provides first-hand preclinical evidence for COs transplantation as a potential and effective intervention for stroke treatment. Electronic supplementary material The online version of this article (10.1007/s12975-019-00773-0) contains supplementary material, which is available to authorized users.

Hypertension is a serious public health problem worldwide. MT-1207, chemically named 3-(4-(4-(1H-benzotriazole-1-yl)butyl)piperazine-1-yl) benzisothiazole hydrochloride, is a new chemical entity that has entered into clinical trial as antihypertensive agent in China. In this paper we report the pharmacological profile of MT-1207 regarding its acute, subacute, and long-term effects on hypertensive animal models, and its actions on isolated organs in vitro as well as its molecular targets. Blood pressure (BP) was measured in conscious animals; amlodipine was taken as a positive control drug. We showed that both single dose of MT-1207 (1.25−20 mg/kg, ig) in spontaneously hypertensive rats (SHR) and MT-1207 (0.25−6 mg/kg, ig) in two-kidney one-clip (2K1C) dogs dose-dependently decreased BP. MT-1207 quickly decreased BP within 5 min after administration; the hypotensive effect lasted for 8 and 12 h, respectively, in SHR and 2K1C dogs without reflex increase in heart rate. Multiple doses of MT-1207 (5 mg · kg(−1) · d(−1) in SHR; 2 mg · kg(−1) · d(−1) in 2K1C dogs, for 7 days) significantly decreased BP, slightly reduced heart rate, and both of them recovered after withdrawal. Long-term administration of MT-1207 (10 mg · kg(−1) · d(−1) for 4 months or more time) produced a stable BP reduction, improved baroreflex sensitivity, reduced renal and cardiovascular damage in SHR, and delayed stroke occurrence and death in stroke-prone SHR. In isolated rat aortic rings precontracted by adrenaline, KCl, noradrenaline or 5-hydroxytryptamine (5-HT), MT-1207 (10(−9)–10(−4) M) caused concentration-dependent relaxation. In a panel of enzyme activity or radioligand binding assays of 87 molecular targets, MT-1207 potently inhibited adrenergic α(1A), α(1B), α(1D), and 5-HT(2A) receptors with K(i)

Summary Aim NAMPT is a novel therapeutic target of ischemic stroke. The aim of this study was to investigate the effect of a potential NAMPT activator, P7C3-A20, an aminopropyl carbazole derivative, on ischemic stroke. Methods In vitro study, neuron protection effect of P7C3-A20 was investigated by co-incubation with primary neurons subjected to oxygen–glucose deprivation (OGD) or oxygen–glucose deprivation/reperfusion (OGD/R) injury. In vivo experiment, P7C3-A20 was administrated in middle cerebral artery occlusion (MCAO) rats and infarct volume was examined. Lastly, the brain tissue nicotinamide adenine dinucleotide (NAD) levels were detected in P7C3-A20 treated normal or MCAO mice. Results Cell viability, morphology, and Tuj-1 staining confirmed the neuroprotective effect of P7C3-A20 in OGD or OGD/R model. P7C3-A20 administration significantly reduced cerebral infarction in MCAO rats. Moreover, brain NAD levels were elevated both in normal and MCAO mice after P7C3-A20 treatment. Conclusions P7C3-A20 has neuroprotective effect in cerebral ischemia. The study contributes to the development of NAMPT activators against ischemic stroke and expands the horizon of the neuroprotective effect of aminopropyl carbazole chemicals.

Adult neurogenesis is the process of generating new neurons throughout life in the olfactory bulb and hippocampus of most mammalian species, which is closely related to aging and disease. Nicotinamide phosphoribosyltransferase (NAMPT), also an adipokine known as visfatin, is the rate-limiting enzyme for mammalian nicotinamide adenine dinucleotide (NAD) salvage synthesis by generating nicotinamide mononucleotide (NMN) from nicotinamide. Recent findings from our laboratory and other laboratories have provided much evidence that NAMPT might serve as a therapeutic target to restore adult neurogenesis. NAMPT-mediated NAD biosynthesis in neural stem/progenitor cells is important for their proliferation, self-renewal, and formation of oligodendrocytes in vivo and in vitro. Therapeutic interventions by the administration of NMN, NAD, or recombinant NAMPT are effective for restoring adult neurogenesis in several neurological diseases. We summarize adult neurogenesis in aging, ischemic stroke, traumatic brain injury, and neurodegenerative disease and review the advances of targeting NAMPT in restoring neurogenesis. Specifically, we provide emphasis on the P7C3 family, a class of proneurogenic compounds that are potential NAMPT activators, which might shed light on future drug development in neurogenesis restoration.

Nicotinamide phosphoribosyltransferase (Nampt) is the rate-limiting enzyme of nicotinamide adenine dinucleotide (NAD) salvage biosynthesis in mammals, and is involved in fundamental physiological processes and pathophysiology of many diseases. Thus far, however, the role of Nampt in atherosclerosis development is still in debate. In this study, we crossed global Nampt transgenic mice (Nampt-Tg) with a well-established atherosclerosis animal model (ApoE knockout mice, ApoE(−/−)) to generate ApoE(−/−);Nampt-Tg mice and investigated the effects of Nampt overexpression on atherosclerosis development in ApoE(−/−) mice. Both ApoE(−/−) and ApoE(−/−);Nampt-Tg mice were fed with a pro-atherosclerotic high-fat diet (HFD) for 16 weeks. Their serum lipid contents and atherosclerotic lesion were assessed. The results showed that there was no significant difference in body weight or serum levels of glucose, total cholesterol, triglycerides, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol between the two strains of mice, but ApoE(−/−);Nampt-Tg mice had a significantly higher level of serum non-esterified fatty acid. Compared with ApoE(−/−) mice, ApoE(−/−);Nampt-Tg mice displayed significantly increased atherosclerotic lesion area and thickness, lower collagen content, decreased collagen I/III ratio (collagen immaturation), increased number of apoptotic cells, and enhanced activities of caspase-3, caspase-8, and caspase-9. Moreover, macrophage infiltration (F4/80 staining), tumor necrosis factor signaling, and chemokines expression (ICAM-1 and CXCR-4) were all activated in aortic atherosclerotic plaque of ApoE(−/−);Nampt-Tg mice compared with ApoE(−/−) mice. Our results provide in vivo evidence that Nampt transgene aggravates atherosclerotic inflammation and promotes atherosclerosis development in ApoE(−/−) mice.

Cancer metabolism and epigenetics are among the most intensely pursued research areas in anticancer drug discovery. Here we report the first small molecules that simultaneously inhibit nicotinamide phosphoribosyltransferase (NAMPT) and histone deacetylase (HDAC), two important targets of cancer metabolism and epigenetics, respectively. Through iterative structure-based drug design, chemical synthesis, and biological assays, a highly potent dual NAMPT and HDAC inhibitor was successfully identified. Compound 35 possessed excellent and balanced activities against both NAMPT (IC50 = 31 nM) and HDAC1 (IC50 = 55 nM). It could effectively induce cell apoptosis and autophagy and ultimately led to cell death. Importantly, compound 35 showed excellent in vivo antitumor efficacy in the HCT116 xenograft model. This proof-of-concept study demonstrates the feasibility of discovering an inhibitor targeting cancer metabolism and epigenetics and provides an efficient strategy for multitarget antitumor drug discovery.

Calorie restriction (CR) is one of the most reproducible treatments for weight loss and slowing aging. However, how CR induces these metabolic alterations is not fully understood. In this work, we studied whether nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme for nicotinamide adenine dinucleotide biosynthesis, plays a role in CR-induced beneficial metabolic effects using a specific inhibitor of NAMPT (FK866). CR upregulated NAMPT mRNA and protein levels in rat skeletal muscle and white adipose tissue. Inhibition of NAMPT activity by FK866 in rats did not affect the SIRT1 upregulation by CR but suppressed the CR-induced SIRT1 activity and deacetylation of Forkhead box protein O1/peroxisome proliferator-activated receptor γ coactivator-1α. Inhibition of NAMPT activity by FK866 also attenuated the CR-induced SIRT3 activity, evidenced by deacetylation of superoxide dismutase-2. Furthermore, FK866 not only weakened the CR-induced decrease of oxidative stress (dichlorofluorescin signal, superoxide , and malondialdehyde levels), but also greatly attenuated the CR-induced improvements of antioxidative activity (total superoxide dismutase, glutathione, and glutathione/oxidized glutathione ratio) and mitochondrial biogenesis (mRNA levels of nuclear respiratory factor 1, cytochrome c oxidase IV, peroxisome proliferator-activated receptor-γ coactivator-1α, and transcription factor A, mitochondrial and citrate synthase activity). At last, FK866 blocked the CR-induced insulin sensitizing, Akt signaling activation, and endothelial nitric oxide synthase phosphorylation. Collectively, our data provide the first evidence that the CR-induced beneficial effects in oxidative stress, mitochondrial biogenesis, and metabolic adaptation require NAMPT.

Summary Background Ambulatory arterial stiffness index (AASI) has been proposed as a new measure of arterial stiffness for predicting cardio–cerebro–vascular morbidity and mortality. However, there has been no research on the direct relationships between AASI and arterial stiffness-determining factors. Methods We utilized beat-to-beat intra-aortic blood pressure (BP) telemetry to characterize AASI in Wistar–Kyoto (WKY) and spontaneously hypertensive rats (SHR). By determination of aortic structural components and analysis of their correlations with AASI, we provided the first direct evidence for the associations between AASI and arterial stiffness-determining factors including the collagen content and collagen/elastin. Results Ambulatory arterial stiffness index was positively correlated with pulse pressure in both WKY and SHR, less dependent on BP and BP variability than pulse pressure, and relatively stable, especially the number of BP readings not less than ~36. The correlations between AASI and aortic components were comparable for various AASI values derived from BP readings not less than ~36. Not only AASI but also BP variability and pulse pressure demonstrated a direct relationship with arterial stiffness. Conclusions These findings indicate AASI may become a routine measure in human arterial stiffness assessment. It is recommended to use a cluster of parameters such as AASI, BP variability, and pulse pressure for evaluating arterial stiffness.

Whether the well-known metabolic switch AMP-activated protein kinase (AMPK) is involved in the insulin-sensitizing effect of calorie restriction (CR) is unclear. In this study, we investigated the role of AMPK in the insulin-sensitizing effect of CR in skeletal muscle. Wild-type (WT) and AMPK-α2−/− mice received ad libitum (AL) or CR (8 weeks at 60% of AL) feeding. CR increased the protein level of AMPK-α2 and phosphorylation of AMPK-α2. In WT and AMPK-α2−/− mice, CR induced comparable changes of body weight, fat pad weight, serum triglycerides, serum nonesterified fatty acids, and serum leptin levels. However, decreasing levels of fasting/fed insulin and fed glucose were observed in WT mice but not in AMPK-α2−/− mice. Moreover, CR-induced improvements of whole-body insulin sensitivity (evidenced by glucose tolerance test/insulin tolerance test assays) and glucose uptake in skeletal muscle tissues were abolished in AMPK-α2−/− mice. Furthermore, CR-induced activation of Akt-TBC1D1/TBC1D4 signaling, inhibition of mammalian target of rapamycin−S6K1−insulin receptor substrate-1 pathway, and induction of nicotinamide phosphoribosyltransferase−NAD+−sirtuin-1 cascade were remarkably impaired in AMPK-α2−/− mice. CR serum increased stability of AMPK-α2 protein via inhibiting the X chromosome-linked ubiquitin-specific protease 9–mediated ubiquitylation of AMPK-α2. Our results suggest that AMPK may be modulated by CR in a ubiquitylation-dependent manner and acts as a chief dictator for the insulin-sensitizing effects of CR in skeletal muscle.

Visfatin (also known as nicotinamide phosphoribosyltransferase and pre-B cell colony-enhancing factor) is a multifunctional protein. Visfatin has been reported to be involved in several biological processes in the cardiovascular system, . However, the role of visfatin in hypertension is still unclear. In this study, we examined the circulating and local adipose visfatin levels in spontaneously hypertensive rats (SHR), stroke-prone spontaneously hypertensive rats (SHR-SP), and in their normotensive control Wistar-Kyoto (WKY). SHR and SHR-SP rats exhibited lower body weight, lower fat tissue and hypolipidemia. No differences of serum visfatin levels were observed in SHR/SHR-SP and WKY. Serum visfatin levels did not correlate to serum glucose, lipids, insulin, and fat pad weights, but significantly correlated to weights of skeletal muscle. Visfatin expression in visceral fat tissue was slightly lower in SHR-SP compared with that in WKY. Moreover, there were no significant differences of visfatin expression in skeletal muscles among WKY, SHR and SHR-SP. Finally, visfatin protein was detected in L6 rat skeletal muscle cell culture medium, indicating that visfatin was secreted from skeletal muscle cells. Thus, our results may provide useful information for understanding the characteristic of visfatin in hypertensive models, and support the view that visfatin may be a myokine.

Aims Perivascular adipose tissue (PVAT) inhibits vascular smooth muscle cell (VSMC) contraction and stimulates VSMC proliferation by releasing protein factors. The present study was to determine whether visfatin is involved in these paracrine actions of PVAT, and if so, to explore the underlying mechanisms. Methods and results Visfatin was preferentially expressed in Sprague–Dawley rat and monkey aortic PVAT, compared with subcutaneous and visceral adipose tissues. The PVAT-derived visfatin was found to be a VSMC growth factor rather than a VSMC relaxing factor, which was proved by visfatin-specific antibody/inhibitor and direct observation of recombinant visfatin. Exogenous visfatin stimulated VSMC proliferation in a dose- and time-dependent manner via extracellular signal-regulated kinase (ERK 1/2) and p38 signalling pathways. This proliferative effect was further confirmed by enhancement of DNA synthesis and upregulation of proliferative marker Ki-67. Visfatin had no anti-apoptotic effect on normal cultured VSMCs, and it exerted an anti-apoptotic effect only during cell apoptosis induced by H2O2, excluding a role of anti-apoptosis in the visfatin-induced VSMC proliferation. Insulin receptor knockdown did not show any action on the visfatin effect. However, visfatin acted as a nicotinamide phosphoribosyltransferase to biosynthesize nicotinamide mononucleotide (NMN), which mediated proliferative signalling pathways and cell proliferation similar to the visfatin effect. Conclusion Visfatin stimulates VSMC proliferation via NMN-mediated ERK1/2 and p38 signalling. The present study provides a molecular link of visfatin to the paracrine action of PVAT, demonstrates a novel function of visfatin in promoting VSMC proliferation, and reveals NMN as a novel signalling molecule that triggers the proliferative process.

Nicotinamide phosphoribosyltransferase (NAMPT) is a promising antitumor target. Novel NAMPT inhibitors with diverse chemotypes are highly desirable for development of antitumor agents. Using high throughput screening system targeting NAMPT on a chemical library of 30000 small-molecules, we found a non-fluorescent compound F671-0003 and a fluorescent compound M049-0244 with excellent in vitro activity (IC50: 85 nM and 170 nM respectively) and anti-proliferative activity against HepG2 cells. These two compounds significantly depleted cellular NAD levels. Exogenous NMN rescued their anti-proliferative activity against HepG2 cells. Structure-activity relationship study proposed a binding mode for NAMPT inhibitor F671-0003 and highlighted the importance of hydrogen bonding, hydrophobic and π-π interactions in inhibitor binding. Imaging study provided the evidence that fluorescent compound M049-0244 (3 μM) significantly stained living HepG2 cells. Cellular fluorescence was further verified to be NAMPT dependent by using RNA interference and NAMPT over expression transgenic mice. Our findings provide novel antitumor lead compounds and a “first-in-class” fluorescent probe for imaging NAMPT.

To investigate the effect of chronic nicotine treatment on vascular function and to identify the underlying mechanisms.Adult rats were treated with nicotine (3 mg·kg(-1)·d(-1), sc) for 6 weeks. After the rats were sacrificed, aortic rings were prepared for detecting vascular reactivity, and thoracic aorta and periaortic fat samples were collected for histological and molecular biology studies.Chronic nicotine treatment significantly reduced periaortic fat, and specifically enhanced smooth muscle relaxation without altering the aortic adventitial fat and endothelium function. Pretreatment with the soluble guanylyl cyclase inhibitor ODQ (3 μmol/L) or PKG inhibitor Rp-8-Br-PET-cGMP (30 μmol/L) abolished the nicotine-induced enhancement of smooth muscle relaxation, whereas the cGMP analogue 8-Br-cGMP could mimic the nicotine-induced enhancement of smooth muscle relaxation. However, the chronic nicotine treatment did not alter PKG protein expression and activity in aortic media.Chronic nicotine treatment enhances vascular smooth muscle relaxation of rats via activation of PKG pathway.

Aims Endothelial dysfunction is an initial and vascular smooth muscle cell (VSMC) apoptosis, a later step of atherosclerosis. Hypothyroidism accelerates atherosclerosis. However, the early events responsible for this pro-atherosclerotic effect are unclear. Methods and results Rats were resistant to induction of atherosclerosis by high cholesterol diet alone, but became susceptible in hypothyroid state achieved by administration of propylthiouracil (PTU) for 6 weeks. VSMC dysfunction and apoptosis were obvious within 1 week after PTU treatment, without signs of endothelial dysfunction. This early VSMC damage was caused by hypothyroidism but not the high cholesterol diet. In ApoE knockout mice, PTU-induced hypothyroidism triggered early VSMC apoptosis, increased oxidative stress, and accelerated atherosclerosis development. Thyroid hormone supplementation (T4, 10, or 50 μg/kg) prevented atherogenic phenotypes in hypothyroid rats and mice. In rats, thyroidectomy caused severe hypothyroidism 5 days after operation, which also led to rapid VSMC dysfunction and apoptosis. In vitro studies did not show a direct toxic effect of PTU on VSMCs. In contrast, thyroid hormone (T3, 0.75 μg/L plus T4, 50 nmol/L) exerted a direct protection against VSMC apoptosis, which was reduced by knockdown of TRα1, rather than TRβ1 and TRβ2 receptors. TRα1-mediated inhibition of apoptotic signalling of JNKs and caspase-3 contributed to the anti-apoptotic action of thyroid hormone. Conclusion These findings provide an in vivo example for VSMC apoptosis as an early trigger of hypothyroidism-associated atherosclerosis, and reveal activation of TRα1 receptors to prevent VSMC apoptosis as a therapeutic strategy in this disease.

This study was to investigate the effect of nicotine on insulin sensitivity and explore the underlying mechanisms. Treatment of Sprague-Dawley rats with nicotine (3 mg/kg/day) for 6 weeks reduced 43% body weight gain and 65% blood insulin level, but had no effect on blood glucose level. Both insulin tolerance test and glucose tolerance test demonstrated that nicotine treatment enhanced insulin sensitivity. Pretreatment of rats with hexamethonium (20 mg/kg/day) to antagonize peripheral nicotinic receptors except for α7 nicotinic acetylcholine receptor (α7-nAChR) had no effect on the insulin sensitizing effect of nicotine. However, the insulin sensitizing effect but not the bodyweight reducing effect of nicotine was abrogated in α7-nAChR knockout mice. Further, chronic treatment with PNU-282987 (0.53 mg/kg/day), a selective α7-nAChR agonist, significantly enhanced insulin sensitivity without apparently modifying bodyweight not only in normal mice but also in AMP-activated kinase-α2 knockout mice, an animal model of insulin resistance with no sign of inflammation. Moreover, PNU-282987 treatment enhanced phosphorylation of signal transducer and activator of transcription 3 (STAT3) in skeletal muscle, adipose tissue and liver in normal mice. PNU-282987 treatment also increased glucose uptake by 25% in C2C12 myotubes and this effect was total abrogated by STAT3 inhibitor, S3I-201. All together, these findings demonstrated that nicotine enhanced insulin sensitivity in animals with or without insulin resistance, at least in part via stimulating α7-nAChR-STAT3 pathway independent of inflammation. Our results contribute not only to the understanding of the pharmacological effects of nicotine, but also to the identifying of new therapeutic targets against insulin resistance.

Obesity is an important risk factor for cardiovascular disease, diabetes and certain cancers. The fat mass– and obesity-associated (FTO) gene is tightly associated with the pathophysiology of obesity, whereas the exact role of FTO remains poorly understood. Here, we investigated the alternations of FTO mRNA and protein expression in the peripheral metabolic tissues and the brain upon energy restriction (ER) and explored the involvement of the leptin signaling pathway in FTO regulation under ER status. ER decreased the FTO mRNA and protein expression in hypothalamus and brainstem but not in periphery. Using double-immunofluorescence staining, FTO was found to be colocalized with the leptin receptor long isoform (LepRb) in arcuate nucleus of hypothalamus and the nucleus of the solitary tract. In LepRb mutant db/db mice, the FTO downregulation in brain and body weight reduction induced by ER were completely abolished. The enhanced phosphorylation of signal transducer and activator of transcription 3 (STAT3) induced by ER was also impaired in db/db mice. Moreover, leptin directly activated the STAT3 signaling pathway and downregulated FTO in in vitro arcuate nucleus of hypothalamus cultures and in vivo wild-type mice but not db/db mice. Thus, our results provide the first evidence that the LepRb-STAT3 signaling pathway is involved in the brain FTO downregulation during ER.

1. Visfatin (also known as nicotinamide phosphoribosyltransferase or Nampt) is a novel adipokine associated with metabolic abnormalities in obesity and diabetes. The aim of the present study was to determine whether visfatin levels in the circulation and visfatin expression in fat tissues are altered in Lyon hypertensive (LH) rats, a hypertensive strain with numerous metabolic abnormalities, and, if so, to explore the possible correlations between blood visfatin levels and the metabolic abnormalities in LH rats. 2. Male 18-20-week-old LH rats and their control, Lyon normotensive (LN) rats, were used. Blood pressure was recorded in conscious, unrestrained rats. Fat tissue weight was determined. Serum visfatin concentrations were determined by enzyme immunoassay, whereas visfatin expression in fat tissues was determined by western blotting. Relationships between two parameters were evaluated by linear regression analysis. 3. The LH rats had significantly higher bodyweight and fat tissue weight compared with LN rats. Serum lipid levels of total cholesterol (TC), high-density lipoprotein-cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C) and triglyceride (TG) were all significantly higher in LH rats than in LN rats. Moreover, serum visfatin levels were higher in LH rats than in LN rats and were positively correlated with bodyweight, fat tissue weight and serum lipid levels (i.e. TC, HDL-C, LDL-C, TG and the TG:HDL-C ratio). There were no significant differences in serum glucose and insulin concentrations, or in the whole-body insulin resistance index, between LN and LH rats, and serum visfatin levels were not correlated with any of these parameters. Visfatin expression in visceral fat tissue, but not in subcutaneous fat tissue, was markedly upregulated in LH compared with LN rats. 4. In conclusion, the results of the present study demonstrate that serum visfatin levels in LH rats are elevated and are associated with lipid metabolic abnormalities.

1. Endoplasmic reticulum (ER) stress plays a role in the pathogenesis of diabetes. The aim of the present study was to investigate the effect of 4-phenyl butyric acid (PBA), a novel chemical chaperone reducing ER stress, on serum glucose level in different strains of normal and diabetic rodents. 2. 4-Phenyl butyric acid (1 g/kg per day, i.g.) was administered to ob/ob Type 2 diabetic mice, alloxan-induced Type 1 diabetic mice and hydrocortisone (HC)-induced Type 2 diabetic mice as well as normal C57BL/6J mice and Kumming mice for 14 days to evaluate its effect on serum glucose levels. In addition, mice were treated simultaneously with PBA (1 g/kg per day) and HC for 9 days to determine its preventive effect against the development of insulin resistance. PBA (0.7 and 1.4 g/kg per day) was administered to non-obese Type 2 diabetic Goto-Kakizaki (GK) and normal Wistar-Kyoto (WKY) rats for 14 and 7 days, respectively, to determine its effects on serum glucose levels. 3. 4-Phenyl butyric acid significantly reduced serum glucose levels in obese Type 2 diabetic ob/ob mice. Normoglycaemia was obtained in ob/ob mice after 4 days of PBA treatment and was maintained for up to 14 days treatment. 4. 4-Phenyl butyric acid had no glucose-lowering effect in alloxan-induced Type 1 diabetic mice, HC-induced Type 2 diabetic mice and non-obese Type 2 diabetic GK rats. In addition, it had no beneficial effects on insulin resistance in HC-treated mice. 5. 4-Phenyl butyric acid did not affect normal serum glucose levels in C57BL/6 J mice, Kunming mice or WKY rats. 6. In conclusion, PBA does not generally reduce glucose levels in rodent models of diabetes, although it can normalize glucose levels in ob/ob diabetic mice, indicating that restoration of ER function as diabetes therapy is limited to conditions under which ER stress is involved in the high glucose levels.