Diet-induced Diabetic Mice Research Articles

Coffee pulp improves glucose and lipid metabolism disorder in high-fat diet-induced diabetic mice

BackgroundCoffee berry extracts are anti-lipogenic and lipolytic. This study aims to investigate the effect and mechanism of coffee pulp on high-fat diet (HFD)-induced glucose and lipid metabolism disorder in mice. MethodsThe type 2 diabetes (T2D) mouse model was established by feeding the C57BL/6 J mice with HFD. Mice were administered with coffee pulp diluted in drinking water before or after the establishment of the T2D mouse model. After treatment, the body weight and fasting blood glucose (FBG) of mice were monitored; the intraperitoneal glucose tolerance test (IPGTT) of mice was performed; plasma insulin was determined by ELISA; serum total cholesterol (TC), triglyceride (TG) and liver TG were determined by biochemical analysis; hematoxylin-eosin (H&E) staining was used to evaluate organ histomorphology. Gene expression of key genes in de novo lipogenesis (DNL) in the liver was examined by quantitative reverse transcription PCR (RT-qPCR). ResultsMice that consumed coffee pulp after modeling showed reduced FBG and liver TG, improved IPGTT, and alleviated fatty liver. Consuming coffee pulp before modeling prevented HFD-induced blood glucose and plasma TG increases. Mice consuming coffee pulp also had lower body fat and liver TG compared to the model group. qPCR results showed that the expression of transcription factors (Srebp1, PPARγ) and genes (Fasn, CideA, Plin3, Plin4, Plin5) related to DNL and lipid droplets (LD) formation in the liver of mice consuming coffee pulp were significantly lower than those of the control group. ConclusionsOur study demonstrated that coffee pulp can attenuate HFD-induced disorders of glucose and lipid metabolism, and this effect may be related to the key pathways of lipid synthesis DNL and LD formation pathways in the liver.

Intermittent hypoxia exacerbates anxiety in high-fat diet-induced diabetic mice by inhibiting TREM2-regulated IFNAR1 signaling

BackgroundType 2 diabetes mellitus (T2DM) and obstructive sleep apnea (OSA) are mutual risk factors, with both conditions inducing cognitive impairment and anxiety. However, whether OSA exacerbates cognitive impairment and anxiety in patients with T2DM remains unclear. Moreover, TREM2 upregulation has been suggested to play a protective role in attenuating microglia activation and improving synaptic function in T2DM mice. The aim of this study was to explore the regulatory mechanisms of TREM2 and the cognitive and anxiety-like behavioral changes in mice with OSA combined with T2DM.MethodsA T2DM with OSA model was developed by treating mice with a 60% kcal high-fat diet (HFD) combined with intermittent hypoxia (IH). Spatial learning memory capacity and anxiety in mice were investigated. Neuronal damage in the brain was determined by the quantity of synapses density, the number and morphology of brain microglia, and pro-inflammatory factors. For mechanism exploration, an in vitro model of T2DM combined with OSA was generated by co-treating microglia with high glucose (HG) and IH. Regulation of TREM2 on IFNAR1-STAT1 pathway was determined by RNA sequencing and qRT-PCR.ResultsOur results showed that HFD mice exhibited significant cognitive dysfunction and anxiety-like behavior, accompanied by significant synaptic loss. Furthermore, significant activation of brain microglia and enhanced microglial phagocytosis of synapses were observed. Moreover, IH was found to significantly aggravate anxiety in the HFD mice. The mechanism of HG treatment may potentially involve the promotion of TREM2 upregulation, which in turn attenuates the proinflammatory microglia by inhibiting the IFNAR1-STAT1 pathway. Conversely, a significant reduction in TREM2 in IH-co-treated HFD mice and HG-treated microglia resulted in the further activation of the IFNAR1-STAT1 pathway and consequently increased proinflammatory microglial activation.ConclusionsHFD upregulated the IFNAR1-STAT1 pathway and induced proinflammatory microglia, leading to synaptic damage and causing anxiety and cognitive deficits. The upregulated TREM2 inT2DM mice brain exerted a negative regulation of the IFNAR1-STAT1 pathway. Mice with T2DM combined with OSA exacerbated anxiety via the downregulation of TREM2, causing heightened IFNAR1-STAT1 pathway activation and consequently increasing proinflammatory microglia.Graphical

Dihydromyricetin ameliorates diabetic renal fibrosis via regulating SphK1 to suppress the activation of NF-κB pathway

Dihydromyricetin (DHM) is a flavonoid from vine tea with broad pharmacological benefits, which improve inflammation by blocking the NF-κB pathway. A growing body of research indicates that chronic kidney inflammation is vital to the pathogenesis of diabetic renal fibrosis. Sphingosine kinase-1 (SphK1) is a key regulator of diabetic renal inflammation, which triggers the NF-κB pathway. Hence, we evaluated whether DHM regulates diabetic renal inflammatory fibrosis by acting on SphK1. Here, we demonstrated that DHM effectively suppressed the synthesis of fibrotic and inflammatory adhesion factors like ICAM-1, and VCAM-1 in streptozotocin-treated high-fat diet-induced diabetic mice and HG-induced glomerular mesangial cells (GMCs). Moreover, DHM significantly suppressed NF-κB pathway activation and reduced SphK1 activity and protein expression under diabetic conditions. Mechanistically, the results of molecular docking, molecular dynamics simulation, and cellular thermal shift assay revealed that DHM stably bound to the binding pocket of SphK1, thereby reducing sphingosine-1-phosphate content and SphK1 enzymatic activity, which ultimately inhibited NF-κB DNA binding, transcriptional activity, and nuclear translocation. In conclusion, our data suggested that DHM inhibited SphK1 phosphorylation to prevent NF-κB activation thus ameliorating diabetic renal fibrosis. This supported the clinical use and further drug development of DHM as a potential candidate for treating diabetic renal fibrosis.

MiR-449a disturbs atherosclerotic plaque stability in streptozotocin and high-fat diet-induced diabetic mice by targeting CEACAM1

BackgroundEmerging evidence indicates carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) is involved in the development of atherosclerosis (AS). However, the roles and functions of CEACAM1 in AS remain unknown. Therefore, this study aims to investigate the roles and molecular functions of CEACAM1 in AS.MethodsWe constructed a diabetes mellitus (DM) + high-fat diet (HFD) mouse model based on the streptozotocin (STZ)-induced apolipoprotein E-knockdown (ApopE−/−) mouse to investigate the roles and regulatory mechanism of miR-449a/CEACAM1 axis. The mRNA expression and protein levels in this study were examined using quantity PCR, western blot, immunofluorescence (IF), enzyme-linked immunosorbent assay (ELISA), and immunohistochemistry (IHC), respectively. And the lipid deposition and collagen content were detected using Oil Red O and Sirius Red staining. Cell apoptosis, migration, invasion, and tuber formation were detected by Annexin-V FITC/PI, wound healing, transwell, and tuber formation assays, respectively. The relationship between miR-449a and CEACAM1 was determined by a dual-luciferase reporter gene assay.ResultsmiR-449a and MMP-9 were upregulated, and CEACAM1 was downregulated in the DM + HFD MOUSE model. Upregulation of CEACAM1 promoted atherosclerotic plaque stability and inhibited inflammation in the DM + HFD mouse model. And miR-449a directly targeted CEACAM1. Besides, miR-449a interacted with CEACAM1 to regulate atherosclerotic plaque stability and inflammation in DM-associated AS mice. In vitro, the rescue experiments showed miR-449a interacted with CEACAM1 to affect apoptosis, migration, invasion, and tuber formation ability in high glucose (HG)-induced HUVECs.ConclusionThese results demonstrated that miR-449a promoted plaque instability and inflammation in DM and HFD-induced mice by targeting CEACAM1.

Fucoidan Improves Early Stage Diabetic Nephropathy via the Gut Microbiota-Mitochondria Axis in High-Fat Diet-Induced Diabetic Mice.

Diabetic nephropathy (DN) is a common microvascular complication of diabetes. Fucoidan, a polysaccharide containing fucose and sulfate group, ameliorates DN. However, the underlying mechanism has not been fully understood. This study aimed to explore the effects and mechanism of fucoidan on DN in high-fat diet-induced diabetic mice. A total of 90 C57BL/6J mice were randomly assigned to six groups (n = 15) as follows: normal control (NC), diabetes mellitus (DM), metformin (MTF), low-dose fucoidan (LFC), medium-dose fucoidan (MFC), and high-dose fucoidan (HFC). A technique based on fluorescein isothiocyanate (FITC-sinistin) elimination kinetics measured percutaneously was applied to determine the glomerular filtration rate (GFR). After 24 weeks, the mice were sacrificed and an early stage DN model was confirmed by GFR hyperfiltration, elevated urinary creatinine, normal urinary albumin, tubulointerstitial fibrosis, and glomerular hypertrophy. Fucoidan significantly improved the GFR hyperfiltration and renal fibrosis. An enriched SCFAs-producing bacteria and increased acetic concentration in cecum contents were found in fucoidan groups, as well as increased renal ATP levels and improved mitochondrial dysfunction. The renal inflammation and fibrosis were ameliorated through inhibiting the MAPKs pathway. In conclusion, fucoidan improved early stage DN targeting the microbiota-mitochondria axis by ameliorating mitochondrial oxidative stress and inhibiting the MAPKs pathway.

Deficiency of neutral cholesterol ester hydrolase 1 (NCEH1) impairs endothelial function in diet-induced diabetic mice

BackgroundNeutral cholesterol ester hydrolase 1 (NCEH1) plays a critical role in the regulation of cholesterol ester metabolism. Deficiency of NCHE1 accelerated atherosclerotic lesion formation in mice. Nonetheless, the role of NCEH1 in endothelial dysfunction associated with diabetes has not been explored. The present study sought to investigate whether NCEH1 improved endothelial function in diabetes, and the underlying mechanisms were explored.MethodsThe expression and activity of NCEH1 were determined in obese mice with high-fat diet (HFD) feeding, high glucose (HG)-induced mouse aortae or primary endothelial cells (ECs). Endothelium-dependent relaxation (EDR) in aortae response to acetylcholine (Ach) was measured.ResultsResults showed that the expression and activity of NCEH1 were lower in HFD-induced mouse aortae, HG-exposed mouse aortae ex vivo, and HG-incubated primary ECs. HG exposure reduced EDR in mouse aortae, which was exaggerated by endothelial-specific deficiency of NCEH1, whereas NCEH1 overexpression restored the impaired EDR. Similar results were observed in HFD mice. Mechanically, NCEH1 ameliorated the disrupted EDR by dissociating endothelial nitric oxide synthase (eNOS) from caveolin-1 (Cav-1), leading to eNOS activation and nitric oxide (NO) release. Moreover, interaction of NCEH1 with the E3 ubiquitin-protein ligase ZNRF1 led to the degradation of Cav-1 through the ubiquitination pathway. Silencing Cav-1 and upregulating ZNRF1 were sufficient to improve EDR of diabetic aortas, while overexpression of Cav-1 and downregulation of ZNRF1 abolished the effects of NCEH1 on endothelial function in diabetes. Thus, NCEH1 preserves endothelial function through increasing NO bioavailability secondary to the disruption of the Cav-1/eNOS complex in the endothelium of diabetic mice, depending on ZNRF1-induced ubiquitination of Cav-1.ConclusionsNCEH1 may be a promising candidate for the prevention and treatment of vascular complications of diabetes.

TOX3 deficiency mitigates hyperglycemia by suppressing hepatic gluconeogenesis through FoxO1

BackgroundExcessive hepatic glucose production is a hallmark that contributes to hyperglycemia in type 2 diabetes (T2D). The regulatory network governing this process remains incompletely understood. Here, we demonstrate that TOX3, a high-mobility group family member, acts as a major transcriptional driver for hepatic glucose production. MethodsTox3-overexpressed and knockout mice were constructed to explore its metabolic functions. Transcriptomic and chromatin-immunoprecipitation sequencing (ChIP-seq) were used to identify downstream targets of TOX3. Both FoxO1 silencing and inhibitor approaches were used to assess the contribution of FoxO1. TOX3 expression levels were examined in the livers of mice and human subjects. Finally, Tox3 was genetically manipulated in diet-induced obese mice to evaluate its therapeutic potential. ResultsHepatic Tox3 overexpression activates the gluconeogenic program, resulting in hyperglycemia and insulin resistance in mice. Hepatocyte-specific Tox3 knockout suppresses gluconeogenesis and improves insulin sensitivity. Mechanistically, integrated hepatic transcriptomic and ChIP-seq analyses identify FoxO1 as a direct target of TOX3. TOX3 stimulates FoxO1 transcription by directly binding to and activating its promoter, whereas FoxO1 silencing abrogates TOX3-induced dysglycemia in mice. In human subjects, hepatic TOX3 expression shows a significant positive correlation with blood glucose levels under normoglycemic conditions, yet is repressed by high glucose during T2D. Importantly, hepatic Tox3 deficiency markedly protects against and ameliorates the hyperglycemia and glucose intolerance in diet-induced diabetic mice. ConclusionsOur findings establish TOX3 as a driver for excessive gluconeogenesis through activating hepatic FoxO1 transcription. TOX3 could serve as a promising target for preventing and treating hyperglycemia in T2D.

Validating the Health Benefits of Coffee Berry Pulp Extracts in Mice with High-Fat Diet-Induced Obesity and Diabetes.

The effects of coffee (Coffea arabica L.) berry pulp extracts (CBP extracts) on the improvement of diabetes, obesity, and non-alcoholic fatty liver disease (NAFLD) were evaluated using various in vitro antioxidant activity assays and through a high-fat diet-induced mild diabetic obese mouse model. After an 84-day oral administration of CBP extracts (400-100 mg/kg), bioactivities were evaluated. The in vitro analysis showed the highest DPPH● scavenging activity of 73.10 ± 4.27%, ABTS● scavenging activity of 41.18 ± 1.14%, and SOD activity of 56.24 ± 2.81%, at a CBP extract concentration of 1000 µg/mL. The in vivo analysis of the CBP extracts showed favorable and dose-dependent anti-obesity, anti-diabetic, NAFLD, nephropathy, and hyperlipidemia refinement effects through hepatic glucose enzyme activity, 5'-AMP-activated protein kinase (AMPK) up-regulation, antioxidant activity, lipid metabolism-related gene expression, and pancreatic lipid digestion enzyme modulatory activities. This study shows that an appropriate oral dosage of CBP extracts could function as a potent herbal formulation for a refinement agent or medicinal food ingredient to control type 2 diabetes and related complications.

Licochalcone A alleviates abnormal glucolipid metabolism and restores energy homeostasis in diet-induced diabetic mice.

Licochalcone A (LCA) is a bioactive chalcone compound identified in licorice. This study aimed to investigate the effects of LCA on glucolipid metabolism and energy homeostasis, as well as the underlying mechanisms. Blood glucose levels, oral glucose tolerance, serum parameters, and histopathology were examined in high-fat-high-glucose diet (HFD)-induced diabetic mice, with metformin as a positive control. Additionally, changes in key markers related to glucolipid metabolism and mitochondrial function were analyzed to comprehensively assess LCA's effects on metabolism. The results showed that LCA alleviated metabolic abnormalities in HFD-induced diabetic mice, which were manifested by suppression of lipogenesis, promotion of lipolysis, reduction of hepatic steatosis, increase in hepatic glycogenesis, and decrease in gluconeogenesis. In addition, LCA restored energy homeostasis by promoting mitochondrial biogenesis, enhancing mitophagy, and reducing adenosine triphosphate production. Mechanistically, the metabolic benefits of LCA were associated with the downregulation of mammalian target of rapamycin complex 1 and activation of adenosine monophosphate-activated protein kinase, the two central regulators of metabolism. This study demonstrates that LCA can alleviate abnormal glucolipid metabolism and restore energy balance in diet-induced diabetic mice, highlighting its therapeutical potential for the treatment of diabetes.

Intermedin alleviates diabetic vascular calcification by inhibiting GLUT1 through activation of the cAMP/PKA signaling pathway

Background and aimsVascular calcification (VC) is regarded as an independent risk factor for cardiovascular events in type 2 diabetic patients. Glucose transporter 1 (GLUT1) involves VC. Intermedin/Adrenomedullin-2 (IMD/ADM2) is a cardiovascular protective peptide that can inhibit multiple disease-associated VC. However, the role and mechanism of IMD in diabetic VC remain unclear. Here, we investigated whether IMD inhibits diabetic VC by inhibiting GLUT1. Methods and resultsIt was found that plasma IMD concentration was significantly decreased in type 2 diabetic patients and in fructose-induced diabetic rats compared with that in controls. Plasma IMD content was inversely correlated with fasting blood glucose level and VC severity. IMD alleviated VC in fructose-induced diabetic rats. Deficiency of Adm2 aggravated and Adm2 overexpression attenuated VC in high-fat diet-induced diabetic mice. In vitro, IMD mitigated high glucose-induced calcification of vascular smooth muscle cells (VSMCs). Mechanistically, IMD reduced advanced glycation end products (AGEs) content and the level of receptor for AGEs (RAGE). IMD decreased glucose transporter 1 (GLUT1) levels. The inhibitory effect of IMD on RAGE protein level was blocked by GLUT1 knockdown. GLUT1 knockdown abolished the effect of IMD on alleviating VSMC calcification. IMD receptor antagonist IMD17-47 and cyclic adenosine monophosphate/protein kinase A (cAMP/PKA) inhibitor H89 abolished the inhibitory effects of IMD on GLUT1 and VSMC calcification. ConclusionsThese findings revealed that IMD exerted its anti-calcification effect by inhibiting GLUT1, providing a novel therapeutic target for diabetic VC.

Impaired colonic motility in high-glycemic diet-induced diabetic mice is associated with disrupted gut microbiota and neuromuscular function.

Similar to the high-fat diet (HFD), the high-glycemic diet (HGD) contributes to the development and progression of type 2 diabetes mellitus (T2DM). However, the effect of HGD on gastrointestinal motility in T2DM and its underlying mechanisms remain unclear. Thirty C57BL/6J mice were randomly designated into the normal-feeding diet (NFD) group, HFD group, and HGD group. The plasma glucose, plasma insulin, and gastrointestinal motility were examined. Meanwhile, the tension of isolated colonic smooth muscle rings was calculated, and the gut microbiota was analyzed by 16s rDNA high-throughput sequencing. After 16 weeks of HGD feeding, obesity, hyperglycemia, insulin resistance, and constipation were observed in HGD mice. Autonomic contraction frequency of the colonic neuromuscular system and electrical field stimulation-induced contractions were reduced in HGD mice. On the contrary, neuronal nitric oxide synthase activity and neuromuscular relaxation were found to be enhanced. Finally, gut microbiota analysis revealed that Rhodospirillaceae abundance significantly increased at the family level in HGD mice. At the genus level, the abundance of Insolitispirillum increased remarkably, whereas Turicibacter abundance decreased significantly in HGD mice. HGD induced constipation in obese diabetic mice, which we speculated that it may be related to neuromuscular dysmotility and intestinal microbiota dysbiosis.

Response surface methodology based development of an optimized polyherbal formulation and evaluation of its anti-diabetic and anti-obesity potential in high-fat diet-induced obese mice

Background and aimThe seeds of Nelumbo nucifera, Chenopodium quinoa and Salvia hispanica are known as super foods due to their various therapeutic properties. The present study aimed to develop an optimized polyherbal formulation from edible seeds aqueous extract and to evaluate its anti-diabetic and lipase inhibitory effect on diet-induced obese diabetic mice. Experimental procedureResponse surface methodology based various formulations were evaluated for their potent anti-diabetic, lipase-inhibitory and antioxidant activities. Acute toxicity of the best optimized formulation was conducted. The mice were fed a high fat diet for 10 weeks resulting in hyperglycemia and obesity. Oral tolerance tests (sucrose, starch and lipid) of the formulation were performed. The mice were supplemented with different doses (125, 250 and 500 mg/kg) of the formulation for 6 weeks. The body weight and blood glucose level were monitored on a weekly basis. Finally, histological alterations and lipid profiles were analysed. Results and conclusionThe formulation containing equal concentration (1.5 mg/ml) of each seed extract showed maximum bioactivities. The formulation was found to be safe during toxicity assay. The tolerance tests supported the anti-diabetic and anti-obesity effect. Higher dose (500 mg/kg) of the formulation significantly (p < 0.01) lowered elevated fasting blood glucose, lipid indices and ameliorated the histological alterations in liver, kidney and pancreas caused by high fat diet. We demonstrated for the first time that the developed aqueous extract optimized formulation possess anti-diabetic and anti-obesity potential and thus could be used as adjuvant therapy for holistic management of type 2 diabetes mellitus.

749-P: Selection of BI 456906 as a Dual GCGR/GLP-1R Agonist Based on In Vitro Potency and In Vivo Target Engagement Biomarkers

Glucagon (GCG) and glucagon-like peptide 1 (GLP-1) are peptide hormones that pharmacologically regulate bodyweight by increasing energy expenditure and reducing energy intake, respectively. Several dual (GCG receptor [GCGR]/GLP-1 receptor [GLP-1R]) agonistic peptides are in clinical development for obesity. We describe preclinical data leading to selection of BI 456906 as a dual agonist. Functional potencies of the compounds were determined in CHO-K1 cells stably expressing human GCGR and GLP-1R. EC50 for GCGR mediated cAMP increase were 0.52 nM for BI 456906, 0.92 nM for BI 456908 and 0.44 nM for BI 456987. EC50 for GLP-1R engagement were 0.33 nM, 0.61 nM and 1.43 nM, respectively. Upon acute, single dosing to lean mice, engagement of the GCGR and GLP-1R was determined by testing for improvement in oral glucose tolerance (30 nmol/kg) and increase in plasma FGF-21 and liver nicotinamide N-methyltransferase mRNA expression (100 nmol/kg), respectively. Specificity of the biomarkers was confirmed using the selective GLP-1R agonist semaglutide and GLP-1R knockout mice. Bodyweight and glucose lowering (HbA1c) efficacies were investigated in subchronic dosing studies in diet-induced obese (DIO) and diabetic (db/db) mice, respectively. In DIO mice, BI 456906 (30 nmol/kg qd), BI 456908 (30 nmol/kg qd) and BI 456897 (10 nmol/kg qd) achieved bodyweight lowering from baseline of 25%, 27%, and 26%, respectively. In db/db mice, BI 456906 and BI 456908 (10 and 20 nmol/kg qd) substantially lowered HbA1c (0.4-0.6%); no clear effect was observed for BI 456897 (3 and 7 nmol/kg qd). As a balanced GCGR/GLP-1R agonist with robust in vivo efficacy BI 456906 (30 nmol/kg qd) was further characterized, and superior bodyweight lowering (32% vs 27%; p&amp;lt;0.05) was seen versus a maximally effective semaglutide dose (100 nmol/kg qd). This was attributed to an increase in energy expenditure. The selected candidate, BI 456906, is currently in clinical development in people with obesity and NASH. Disclosure R.Augustin: None. L.Thomas: Employee; Boehringer Ingelheim Pharma GmbH&amp;Co.KG. T.Zimmermann: Employee; Boehringer Ingelheim Pharma GmbH&amp;Co.KG. E.Simon: Employee; Boehringer Ingelheim Pharma GmbH&amp;Co.KG. W.Rist: None. I.Uphues: Employee; Boehringer Ingelheim Pharma GmbH&amp;Co.KG. W.Reindl: None. T.Klein: Employee; Boehringer Ingelheim Pharma GmbH&amp;Co.KG. H.Neubauer: None. Funding Zealand Pharma A/S; Boehringer Ingelheim

297-LB: Dorzagliatin, a Glucokinase Activator, Repairs Defective Islet Function in High-Fat Diet-Induced Diabetic Mice

The DREAM study showed long-term benefits for glucose control in newly diagnosed type 2 diabetes (T2D) patients even after withdrawal of dorzagliatin treatment, a newly approved glucokinase activator for T2D treatment, who were considered to be in the remission for diabetes. The purpose of the current study is to examine the mechanisms of dorzagliatin-induced diabetes remission by evaluating the changes in islet function over time after a period of administering dorzagliatin in high-fat diet (HFD) induced obesity and diabetes mouse models. Diabetes mice were generated after 7 months of HFD, then received dorzagliatin or vehicle controls via oral gavage once a day for 19 days (8 days of 30 mg/Kg and 11 days of 15 mg/Kg). After drug withdrawal, one group of mice remained in HFD and another group changed to a normal diet. Islets were then isolated at different time points after drug withdrawal, and the serum and liver were collected for evaluation. The glucose ramp-stimulated insulin secretion (GSIS) was evaluated in islet perifusion. Gene expression was measured by qPCR in islets and by RNA-seq in the liver. Compared to normal mouse islets, HFD-induced diabetic islets in vehicle groups have impaired GSIS with about 40% reduction in maximum insulin secretion. In contrast, GSIS was fully recovered to the levels of normal islets in 10, 18 and 38 days after dorzagliatin withdrawal, but returned to defective GSIS levels after 45 days of drug discontinuation. In addition, islet GSIS can be fully recovered after 80 days of diet change. In conclusion, the defective GSIS in HFD-induced diabetes mouse islets is reversible and can be fully restored by dorzagliatin even after a long period of drug withdrawal while still remaining in HFD. The mechanisms are likely due to increased glucokinase gene expression caused by a short treatment of dorzagliatin. Diet change alone can recover islet function but requires weight reduction and a longer duration. Disclosure D. Han: Employee; Nanjing AscendRare Pharmaceutical Technology. S. Meng: Employee; Nanjing AscendRare Pharmaceutical Technology. X. Zhou: Employee; Nanjing AscendRare Pharmaceutical Technology. R. Li: Employee; Nanjing AscendRare Pharmaceutical Technology. C. Li: Employee; Hua Medicine, Nanjing AscendRare Pharmaceutical Technology.

Gαi -coupled GPR41 activation increases Ca2+ influx in C2C12 cells and shows a therapeutic effect in diabetic animals.

This study aimed to investigate the possible mechanisms by which orphan G protein-coupled receptor GPR41 activation enhances glucose uptake into C2C12 myotubes using a GPR41-selective agonist, AR420626, and to examine the ability of this agent to improve insulin sensitivity and glucose homeostasis in vivo. Basal and insulin-stimulated glucose uptake and glucose transporter 4 translocations were measured in C2C12 myotubes. Ca2+ influx into cells was measured and GPR41-mediated signaling by AR420626 was examined. An oral glucose tolerance test was performed, and plasma insulin levels were measured in streptozotocin-treated or high-fat diet-fed diabetic mice. The glycogen content was measured in skeletal muscle tissue. AR420626 increased basal and insulin-stimulated glucose uptake, which was reduced by pertussis toxin, an inhibitor of Gαi -mediated signaling, and treatment with small interfering RNA for GPR41 (siGPR41). AR420626 increased intracellular Ca2+ influx and phosphorylated Ca2+ /calmodulin-dependent protein kinase type II, cyclic AMP-responsive element-binding protein, and mitogen-activated protein kinase (p38) in C2C12 myotubes, which were inhibited by treating with pertussis toxin, amlodipine (Ca2+ channel blocker), and siGPR41. AR420626 increased plasma insulin levels and skeletal muscle glycogen content and improved glucose tolerance in streptozotocin- and high-fat diet-induced diabetic mouse models. GPR41 activation with AR420626 increased glucose uptake mediated by Ca2+ signaling via GPR41, improving diabetes mellitus.

Flavonoids by Ultrasonic-Assisted Extraction from Herbal Formulation of Zingiber officinale, Portulaca oleracea, and Tamarindus indica Improved Type 2 Diabetes in C57BL6/J Mice

Background: Diabetes is a problem of public health, in consequence, the increasing prevalence of both diseases needs more functional food products with efficiency and low cost to support treatment. Methods: Flavonoids from the herbal formulation of Portulaca oleracea, Zingiber officinale, and Tamarindus indica were extracted by ultrasound-assisted extraction technology, where several experiments were conducted to determine the implication of three independent variables on the higher production of flavonoids. Extraction time, ethanol concentration, and the liquid-solid ratio were determined as optimal conditions. Furthermore, flavonoids of interest in the extract were determined by using HPLC with UV/vis and mass spectrum and direct comparison reference compounds. Then was determined and compared the effect of extracts from P. oleracea (P), Z. officinale (Z), T. indica (T), and its combination (PTZ) on high-fat-diet-induced diabetic C57BL6/J mice. Results: The optimum conditions provided by the model include an extraction time of 30 min, an ethanol concentration of 50%, and a liquid/solid ratio of 40:1 mL/g, The antidiabetic effect of an extract rich in polyphenolic compounds was evaluated using streptozotocin (STZ) and a high-fat diet-induced diabetic mouse. Effect of extracts on high-fat-diet-induced diabetic mice including decreased FER, improved insulin sensitivity, fasting blood glucose, and serum lipid, and shown reducing body weight gain associated with a reduction of food intake. Extracts have protective effects on kidneys and liver improve lipolysis and successively decrease adipose tissue. Treatment with the polyherbal mixture has shown no toxic effects, possesses potent antihyperlipidemic, antihyperglycemic effects, and decreased glycated hemoglobin. The serum insulin level was significantly increased (p &lt; 0.05) on the polyherbal extract treatment, supporting the evidence of β-cell re-establishment in the pancreas. reduce body weight and food intake, plasma adiponectin level increased while serum leptin level was significantly reduced compared with the HFD group. In addition, the activities of key enzymes of carbohydrate metabolism, antioxidant enzymes, lipid peroxidation markers, and glycogen content were also improved in diabetic mice. Conclusion: The combined form of P. oleracea, Z. officinale, and T. indica had better anti-diabetic properties compared to a single therapy, especially which could be related to their high content of phytochemicals in comparison with the bioactive content of a single plant. The results presented here indicated that the use of PTZ due to their synergistic effects can be useful against diabetes improving the factors associated with this disease.

Dendrobium officinale polysaccharide prevents neuronal apoptosis via TET2-dependent DNA demethylation in high-fat diet-induced diabetic mice

Dendrobium officinale polysaccharide (DP) has the potential function to prevent diabetes-induced neuronal apoptosis, whereas the mechanism is not completely clear. Ten eleven translocation dioxygenase 2 (TET2) is one of the most important therapeutic target for repairing neuronal damage in diabetic mice. The aim of the present study was to investigate whether DP could prevent neuronal apoptosis by regulating TET2 in the brain of HFD-induced diabetic mice. C57BL/6J mice were randomly divided into four groups (n = 12), control group (CON), high-fat diet group (HFD, negative control), metformin group (MET, positive control), and DP group (DP). Compared with HFD group, the neuronal apoptosis of brain was significantly lower in the DP group. The levels of TET2 protein, 5-hydroxymethylcytosine (5hmC) and 5-formylcytosine (5fC) were significantly lower in the HFD group than in both the DP and CON groups in the cerebral cortex of mice. The ratio of p-AMPK/AMPK and α-KG/(fumaric acid + succinic acid) were significantly lower in the HFD group than in the other groups. The present study suggests that DP has a preventive effect on diabetes-induced neuronal apoptosis by regulating TET2 function through improving phosphorylate AMPK and mitochondrial function, thus remodeling DNA epigenetics profile of mice brain.

Thinned young apple polyphenols may prevent neuronal apoptosis by up-regulating 5-hydroxymethylcytosine in the cerebral cortex of high-fat diet-induced diabetic mice.

Apple polyphenols exert neuroprotective effects by improving the mitochondrial tricarboxylic acid (TCA) cycle function, but the details of their mechanisms are still not fully understood. TCA cycle metabolites regulate the level of 5-hydroxymethylcytosine (5hmC) by affecting the ten-eleven translocation (TET) enzyme activity. Therefore, we hypothesized that thinned young apple polyphenols (TYAPs) inhibit neuronal apoptosis by up-regulating the level of 5hmC in the cerebral cortex of high-fat diet-induced diabetic mice. C57BL/6J mice were randomly divided into 5 groups (n = 10 each group): the control (CON) group, the high-fat diet (HFD, negative control) group, the lovastatin (LOV, positive drug control) group, the resveratrol (RES, positive polyphenol control) group and the TYAP group during an eight-week intervention. The presented results verified that in the HFD group, the level of 5hmC and the expression of TET2 in the cerebral cortex were significantly lower, and the ratio of (succinic acid + fumaric acid)/α-ketoglutarate and the neuronal apoptosis rate were significantly higher than those in the CON group. However, TYAP intervention effectively restored the level of 5hmC through up-regulating the expression and activity of TET2, so as to improve diabetes symptoms and prevent diabetes-induced neuronal apoptosis.

Puerarin alleviates depressive-like behaviors in high-fat diet-induced diabetic mice via modulating hippocampal GLP-1R/BDNF/TrkB signaling

ABSTRACT Objective Depression is one of the most common complications in patients with diabetes. Our previous study demonstrated puerarin, a dietary isoflavone, improved glucose homeostasis and β-cell regeneration in high-fat diet (HFD)-induced diabetic mice. Here, we aim to evaluate the potential effect of puerarin on diabetes-induced depression. Methods The co-occurrence of diabetes and depression with related biochemical alterations were confirmed in HFD mice and db/db mice, respectively using behavioral analysis, ELISA and western blotting assay. Furthermore, impacts of puerarin on depression-related symptoms and pathological changes were investigated in HFD mice. Results The results showed that puerarin effectively alleviated the depression-like behaviors of HFD mice, down-regulated serum levels of corticosterone and IL-1β, while up-regulated the content of 5-hydroxytryptamine. Simultaneously, puerarin increased the number of hippocampal neurons in HFD mice, and suppressed the apoptosis of neurons to protect the hippocampal neuroplasticity. GLP-1R expression in hippocampus of HFD mice was enhanced by puerarin, which subsequently activated AMPK, CREB and BDNF/TrkB signaling to improve neuroplasticity. Importantly, our data indicated that puerarin had an advantage over fluoxetine or metformin in treating diabetes-induced depression. Conclusion Taken together, puerarin exerts anti-depressant-like effects on HFD diabetic mice, specifically by improving hippocampal neuroplasticity via GLP-1R/BDNF/TrkB signaling. Puerarin as a dietary supplement might be a potential candidate in intervention of diabetes with comorbid depression.

N-acetyl-L-cysteine treatment reduces beta-cell oxidative stress and pancreatic stellate cell activity in a high fat diet-induced diabetic mouse model.

Obesity plays a major role in type II diabetes (T2DM) progression because it applies metabolic and oxidative stress resulting in dysfunctional beta-cells and activation of intra-islet pancreatic stellate cells (PaSCs) which cause islet fibrosis. Administration of antioxidant N-acetyl-L-cysteine (NAC) in vivo improves metabolic outcomes in diet-induced obese diabetic mice, and in vitro inhibits PaSCs activation. However, the effects of NAC on diabetic islets in vivo are unknown. This study examined if dosage and length of NAC treatment in HFD-induced diabetic mice effect metabolic outcomes associated with maintaining healthy beta-cells and quiescent PaSCs, in vivo. Male C57BL/6N mice were fed normal chow (ND) or high-fat (HFD) diet up to 30 weeks. NAC was administered in drinking water to HFD mice in preventative treatment (HFDpNAC) for 23 weeks or intervention treatment for 10 (HFDiNAC) or 18 (HFDiNAC+) weeks, respectively. HFDpNAC and HFDiNAC+, but not HFDiNAC, mice showed significantly improved glucose tolerance and insulin sensitivity. Hyperinsulinemia led by beta-cell overcompensation in HFD mice was significantly rescued in NAC treated mice. A reduction of beta-cell nuclear Pdx-1 localization in HFD mice was significantly improved in NAC treated islets along with significantly reduced beta-cell oxidative stress. HFD-induced intra-islet PaSCs activation, labeled by αSMA, was significantly diminished in NAC treated mice along with lesser intra-islet collagen deposition. This study determined that efficiency of NAC treatment is beneficial at maintaining healthy beta-cells and quiescent intra-islet PaSCs in HFD-induced obese T2DM mouse model. These findings highlight an adjuvant therapeutic potential in NAC for controlling T2DM progression in humans.