Streptozotocin-induced Type 2 Diabetes Mellitus Research Articles

Network pharmacology-based screening of the active ingredients and mechanisms of Cymbaria daurica against diabetes mellitus

Cymbaria daurica L. has a long history as a folk medicine and tea for the treatment of diabetes. However, the biological activity and mechanism of its hypoglycemic effect have not been fully elucidated. In this study, the potential mechanism of C. daurica against type 2 diabetes mellitus (T2DM) was postulated via pharmacological network analysis. Based on data mining techniques involving topological parameters, gene ontology, and pathway enrichment, we established a compound-target, protein-protein interaction, and target-pathway network to identify central targets and pathways. Pathway enrichment analysis revealed that the most important pathway associated with C. daurica in treating T2DM is the PI3K-Akt signaling pathway. Molecular docking was performed to validate the predicted results. Then, a HepG2 cell insulin resistance model and a high-fat, high-glucose diet combined with a streptozotocin-induced T2DM rat model was established to assess the fasting glucose changes and lipid profile after C. daurica treatment, respectively. Finally, real-time PCR and western blotting were used to verify changes in key targets. The anti-diabetic mechanism of the active ingredient in C. daurica may involve the regulation of IRS-2, Akt1, GLUT4, and GSK3β.

The Effect of Low Doses of Radon on Ghrelin and Glucose Levels in Rats with Multiple Low-Dose Streptozotoccin-induced Type 2 Diabetes Mellitus

AIM: The aim of our research was to identify the ghrelin concentration in experimental animals with type 2 diabetes mellitus (T2DM) and to study the effect of radon hormesis balneotherapy using natural thermal waters of Tskaltubo spring, practically, its effect on ghrelin and glucose metabolism. MATERIALS AND METHODS: To study the effect of radon in balneotherapy, group of experimental animals (multiple low doses streptozotocin-induced T2DM Wistar rats were used) went through the procedure of inhalation of radon by the Tskaltubo mineral water pool, once daily, during 10 days. In animals of the control groups, inhalation with radon was not used. The experimental group and the control group were brought from Tskaltubo to Tbilisi to the Ivane Beritashvili experimental biomedicine center, where the blood of the rats was analyzed. RESULTS: After radon inhalation therapy with Tskaltubo mineral water, a normalization of the ghrelin levels was observed in the experimental group and despite the different body weight, the levels were approximately the same and close to those of the control group. In the experimental group, ghrelin level normalization was accompanied by glycemia normalization. CONCLUSION: This research showed that Tskaltubo mineral water radon inhalation caused hormesis, which consequently decreased ghrelin levels in rodents with T2DM and obesity and the result was stable during 3 months. Ghrelin level stabilization positively influenced on glucose levels. The result of our experiment gives us a stimulus to continue future research to find more specific neurochemical mechanisms participating in radon hormesis processes and positively influencing on glucose levels and T2DM outcome.

Cyclocarya paliurus triterpenoids suppress hepatic gluconeogenesis via AMPK-mediated cAMP/PKA/CREB pathway

BackgroundAbnormal enhancement of hepatic gluconeogenesis is a vital mechanism of the pathogenesis of Type 2 diabetes mellitus (T2DM); thus, its suppression may present an efficient therapeutic strategy for T2DM. Cyclocarya paliurus (CP), a plant species native to China, has been reported to have anti-hyperglycemia activity. Our previous studies have revealed that Cyclocarya paliurus triterpenic acids (CPT) exert the favorable glucose-lowering activity, but the regulatory effect of CPT on hepatic gluconeogenesis is still unclarified. PurposeThis study aimed to investigate the potential role and mechanism of CPT in gluconeogenesis. Study designIn this study, the ameliorative effect and underlying mechanism of CPT on gluconeogenesis were investigated: high-fat diet and streptozotocin-induced T2DM mice and glucagon-challenged mouse primary hepatocytes. MethodsT2DM model mice with or without oral administration of CPT for 4 weeks were monitored for body weight, glucose and lipid metabolism. Hematoxylin and eosin staining was used to observe liver lipid deposition. Real-time PCR assays were performed to examine the mRNA expression of glucose-6-phosphate (G6Pase), and phosphoenolpyruvate carboxykinase (PEPCK), two key enzymes involved in liver gluconeogenesis. Western blotting was used to determine AMP-dependent protein kinase (AMPK) expression and induction of the glucagon signaling pathway. The possible mechanism of CPT on liver gluconeogenesis was further explored in glucagon-induced mouse primary hepatocytes. ResultsIn vivo and in vitro experiments revealed that CPT treatment significantly reduced fasting blood glucose, total cholesterol and triglyceride levels, and improved insulin resistance. Furthermore, CPT could obviously decreased the mRNA and protein expression of G6Pase and PEPCK, the cyclic AMP content, the phosphorylation level of protein kinase A and cyclic AMP response element-binding protein. But CPT promoted the phosphorylation of AMP-dependent protein kinase (AMPK) and activation of phosphodiesterase 4B. Mechanistically, intervention with Compound C (an AMPK inhibitor) partially blocked the suppressive effect of CPT on hepatic gluconeogenesis. ConclusionThese findings suggested that CPT may inhibit hepatic gluconeogenesis against T2DM by activating AMPK.

Antidiabetic activity of Physalis angulata L. fruit juice on streptozotocin-induced diabetic rats

Physalis angulata L. is a plant applied in traditional treatment as a remedy for numerous ailments, which include diabetes mellitus. This study examines the antidiabetic effects of P. angulata fruit extract on streptozotocin-induced type-2 diabetes mellitus in rats. Rats were sorted randomly into five clusters, which are a normal cluster, a diabetic cluster, two diabetic clusters administered with the fruit extract of P. angulata, and a diabetic cluster administered with metformin. The diabetic rats were treated orally using 1 mL and 2 mL of P. angulata fruit extract every day for two weeks. The effects of P. angulata fruit juice were studied by measuring the body weight, Fasting Blood Glucose level, GLUT-4 genes expression and histopathological changes. P. angulata fruit juice significantly decreased the blood glucose level, therefore there is no significant changes of the body weight and upregulate GLUT4 gene expression in the soleus muscle. Histopathological analysis showed significant improvement results of pancreatic tissues that were treated with 2 mL/day compared to 1 mL/day. Furthermore, P. angulata fruit juice contains high concentration of vitamin C and phenolic compounds that could effectively attenuate diabetes. The results obtained provides important information that supports the use of P. angulata fruit in management of diabetes.

Establishment of long-term high-fat diet and low dose streptozotocin-induced experimental type-2 diabetes mellitus model of insulin resistance and evaluation of seed extracts of Syzygium cumini

Introduction: The principal mechanism responsible for reducing blood glucose is through insulin-stimulated glucose transport into skeletal muscle. The transporter protein that mediates this uptake is GLUT-4. A defect in this step is associated with reduced glucose utilization in muscle and adipose tissue, as observed in insulin-resistant type-2 diabetes mellitus (T2DM) patients. This study aimed to develop an experimental T2DM model and evaluate altered glucose transporter type 4 (GLUT-4) levels as a biomarker of insulin resistance. Antidiabetic activities of Syzygium cumini hydro-ethanolic seed extracts (SCE) were also evaluated. Methods: Adult male Wistar albino rats were fed a high-fat diet for 12 weeks and dosed intraperitoneally with streptozotocin (35 mg/kg). After treatment for 21 days, all investigations were done. The homeostasis model of assessment (HOMA) was used for the calculation of insulin resistance (HOMA-IR) and beta-cell function (HOMA-B) index. Diaphragm muscle and retroperitoneal fat were collected for real-time polymerase chain reaction (RT-PCR) studies. Results: A significant increase in fasting blood glucose, HOMA-IR, and serum lipids, and a decrease in serum insulin and HOMA-B were observed in the diabetic group, effects that reversed following pioglitazone and SCE treatment. The diabetic group showed a downregulation of GLUT-4 expression in skeletal muscle while an increase was observed in adipose tissue. Conclusion: A high-fat diet and low dose streptozotocin-induced experimental T2DM model of insulin resistance was developed to screen novel insulin sensitizers. Data generated demonstrated that altered GLUT-4 levels could be used as a biomarker of insulin resistance. Antidiabetic activity of S. cumini hydro-ethanolic seed extract was also confirmed in this study.

Effect of Lupinus rotundiflorus gamma conglutin treatment on JNK1 gene expression and protein activation in a rat model of type 2 diabetes

Context Gamma conglutin (Cγ) from lupine species represents a potential complementary treatment for type 2 diabetes mellitus (T2DM) because of its hypoglycaemic effect. However, its underlying mechanism of action is not fully known. Objective To evaluate whether Cγ from Lupinus rotundiflorus M. E. Jones (Fabaceae) modulates c-Jun N-terminal kinase 1 (JNK1) expression and activation in a T2DM rat model. Materials and methods Gamma conglutin isolated from L. rotundiflorus seeds was characterized by SDS-PAGE. Fifteen Wistar rats with streptozotocin-induced T2DM (HG) were randomized into three groups (n = 5): vehicle administration (HG-Ctrl), oral treatment with Cγ (120 mg/kg/day) (HG-Lr) for one week, and treatment with metformin (300 mg/kg/day) (HG-Met); a healthy group (Ctrl, n = 5) was included as control. The levels of glucose and biomarkers of renal and hepatic function were measured pre- and post-treatment. Hepatic Jnk1 expression and phosphorylation of JNK1 were evaluated by qRT-PCR and western blot, respectively. Results Oral treatment with either Cγ or metformin reduced serum glucose level to 86.30 and 74.80 mg/dL, respectively (p ˂ 0.05), from the basal levels. Jnk1 expression was 0.65- and 0.54-fold lower (p ˂ 0.05) in the HG-Lr and HG-Met groups, respectively, than in HG-Ctrl. Treatment with Cγ decreased JNK1 phosphorylation. However, Cγ did not change the levels of kidney and liver biomarkers. Discussion and conclusions Treatment with Cγ from L. rotundiflorus inhibited Jnk1 expression, in vivo, suggesting JNK1 as a potential therapeutic target in diabetes and revealing one mechanism underlying the hypoglycaemic effect of lupine Cγ. Nevertheless, further studies are required.

The potential therapeutic effects of Lactobacillus plantarum and inulin on serum and testicular reproductive markers in diabetic male rats

BackgroundIt is well established that diminished reproductive health is one of the notable long-term outcomes of type 2 diabetes mellitus (T2DM), especially among males. Due to the global increasing rate of T2DM and infertility, we aimed to investigate the impact of Lactobacillus plantarum (L. plantarum), inulin, and their combinatory supplementation on fertility markers as well as testicular kisspeptin and androgen receptor (AR)’s expression in diabetic male rats.MethodsThirty-five Male Wistar rats with Streptozotocin-induced T2DM were supplemented with L. plantarum, inulin, or their combination for 8 weeks. At the end-point, the animals were sacrificed and serum, testicular, and seminal parameters were studied.ResultsAdministration of L. plantarum and inulin in diabetic male rats improved sperm motility and viability (P < 0.001, both) as well as testicular tissue development via increasing leydig cell number, testicular spermatid count, and diameter of seminiferous tubules (P < 0.001, all). Testicular expression of Kisspeptin was elevated by inulin supplementation (P = 0.01). L. plantarum administration increased testicular AR expression (P = 0.01). The expression of Kisspeptin showed a remarkable correlation with fertility markers (P < 0.001).ConclusionSupplementation with either L. plantarum, inulin, or their combination can prevent infertility caused by T2DM in male rats via improving testicular kisspeptin and AR expression, leydig cell count, and effectively increasing epididymal sperm motility and viability.

An Integrated Fecal Microbiome and Metabolomics in T2DM Rats Reveal Antidiabetes Effects from Host-Microbial Metabolic Axis of EtOAc Extract from Sophora flavescens.

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disease. Sophora flavescens (S. flavescens), also named Kushen, is a famous Chinese herbal medicine that has been used to prevent and cure T2DM both in folk medicine and in medical institution. However, its mechanism of action remains unclear. In this study, the pharmacodynamic effects of S. flavescens EtOAc extract (SFE) on high-fat diet and low-dose streptozotocin-induced T2DM rats were examined. Fecal metabolomics analysis and 16S rRNA gene sequencing were applied to determine the influence of T2DM and SFE treatment on gut microbiota and host metabolism. Based on the consistency of the results of metabolic pathways in metabolomics analysis and phylogenetic investigation of communities by reconstruction of unobserved state (PICRUSt) analysis of 16S rRNA gene sequencing, the level of metabolites and the operational taxonomic units of gut bacteria were combined, and Spearman's analysis was implemented. Our data showed that SFE significantly decreased fasted blood glucose levels and improved lipid profile, glycosylated serum protein, glycosylated hemoglobin index, and pancreas damage. Metabolomics and 16S rRNA gene sequencing analysis indicated gut bacteria disorder, disturbed lipid metabolism, carbohydrate metabolism, and especially amino acid metabolism in T2DM and that SFE can regulated these metabolic pathways through the influence on gut bacteria. Spearman's analysis indicated that the amino acid metabolism that included tryptophan, branched chain amino acid, aromatic amino acid, beta-alanine, and glycine, serine and threonine metabolism, lipid metabolism, including lysophosphatidylcholines and lysophosphatidylethanolamines, primary bile acid and linoleic acid metabolism, carbohydrate metabolism, and nucleotide metabolism positively correlated with Faecalibacterium, Flexispira, Phascolarctobacterium, Prevotella, Roseburia, and [Prevotella]. In addition, arginine and proline metabolism, steroid hormone, steroid biosynthesis, and sphingolipid metabolism positively correlated with Lactobacillus, Oscillospira, Parabacteroides, Ruminococcus, and Streptococcus. Taken together, we speculated that SFE may have an effect on T2DM by mediating host-microbial metabolic axis. Exploration of SFE treatment for T2DM by multiomics is expected to provide a reference for clinical treatment.

Inhibition of GDF11 could promote bone healing in the tooth extraction socket and facilitate mesenchymal stem cell osteogenic differentiation in T2DM pigs.

Growth differentiation factor 11 (GDF11) might be a key factor responsible for the weakening of mesenchymal stem cell (MSC) osteogenic differentiation in tooth extraction sockets in patients with type 2 diabetes mellitus (T2DM). This study aimed to confirm that inhibition of GDF11 could promote bone healing in tooth extraction sockets and facilitate MSC osteogenic differentiation under T2DM conditions. Three streptozotocin-induced T2DM pig models and two control pig models were established. The T2DM pigs were treated with an intrasocket injection of GDF11 inhibitor in the left mandible, whereas the right side was maintained for natural healing. The postextraction socket healing of the T2DM pigs was compared with that of nondiabetic controls. Healing was quantitatively verified by microcomputed tomography, and the GDF11 expression level was detected. MSCs from T2DM pig sockets were cultured and treated with a GDF11 inhibitor. The osteogenic differentiation ability of MSCs was also compared among groups. The expression of GDF11 in the tooth extraction sockets from T2DM pigs increased significantly post extraction. Bone healing was promoted by periodic injection of the GDF11 inhibitor into the extraction sockets of T2DM pigs. Furthermore, the osteogenic differentiation ability of T2DM-MSCs was improved in pigs treated with the GDF11 inhibitor. GDF11 inhibition could promote bone healing in the tooth extraction socket and facilitate MSC osteogenic differentiation under T2DM conditions. GDF11 could be a potential therapeutic target for undesirable alveolar bone healing in T2DM patients.

Anti-Lipid Peroxidation, α-Glucosidase and α-Amylase Inhibitory Effects of the Extract of Capitula of Coreopsis tinctoria Nutt. and Protection Effects on High-Fat/High-Sugar and Streptozotocin-Induced Type 2 Diabetes in Mice.

Coreopsis tinctoria capitula (CTC) of the Compositae family has been used traditionally to treat various diseases in China, particularly type 2 diabetes mellitus (T2DM). This study evaluated the anti-lipid peroxidation, α-glucosidase and α-amylase inhibitory effects of CTC extracts, and analyzed its chemical composition by HPLC. Moreover, the antioxidant activity and protection effects of CTC extracts were investigated on high-fat/high-sugar and streptozotocin-induced T2DM mice. In vitro study, the ethyl acetate extract (EAE) and butanol extract (BE) of CTC exhibited anti-lipid peroxidation (IC50 : BHA>BE or EAE>ascorbic acid, p<0.05) and α-glucosidase inhibitory activity (IC50 : BE>EAE, p<0.05). In vivo, the BE at the dose of 600 mg/kg was intragastrically given to T2DM mice, which exhibited a certain extent of repair and improvement of the levels of CAT, GSH, GSH-PX , SOD, as well as plasma biomarkers, compared with those in the model group (p<0.05). These results demonstrated that CTC extracts have a positive effect to treat T2DM and it can be used for the treatment of T2DM in the future.

Intake of Ganoderma lucidum polysaccharides reverses the disturbed gut microbiota and metabolism in type 2 diabetic rats

Ganoderma lucidum polysaccharides (GLP), a kind of medicinal mushrooms, were widely used in southeastern countries with putative anti-diabetic effects. In order to unravel the underlying mechanism of its anti-diabetic effect, this study examines the effects of GLP on gut microbiota composition and functions in type 2 diabetes mellitus (T2DM) status. In this study, the effects of GLP on the gut microbiota and fecal metabolites in high-fat diet and streptozotocin-induced T2DM rats were examined by 16S rDNA sequencing and 1H NMR profiling. As a result, administration of GLP led to significant decreases in the levels of fasting blood glucose and insulin. Moreover, GLP treatment reduced the abundance of harmful bacteria, such as Aerococcus, Ruminococcus, Corynebactrium and Proteus, and increased the level of Blautia, Dehalobacterium, Parabacteroides and Bacteroides. The PICRUSt analysis indicated that GLP could restore the disturbed amino acids metabolism, carbohydrates metabolism, inflammatory substances metabolism and nucleic acid metabolism of gut bacterial community in T2DM rats and most metabolic changes observed by metabolomics analysis were consistent with these consequences. Taken collectively, GLP can restore the disordered gut microbiota of T2DM rats to a normal level and modify metabolites of the host to realize its antidiabetic effects.

Effect of berberine on the HPA-axis pathway and skeletal muscle GLUT4 in type 2 diabetes mellitus rats.

PurposeActivation of the hypothalamus-pituitary-adrenal (HPA) axis pathway is closely related to insulin resistance (IR), glucose, and lipid metabolism disorders in type 2 diabetes mellitus (T2DM). Berberine (BBR) has effect on regulating disorder of glucose and lipid metabolism in T2DM. In fact, activation of the HPA axis pathway is closely related to IR, glucose, and lipid metabolism disorders in T2DM. Here, we investigated whether the therapeutic effect of BBR on T2DM rats is acted through the HPA axis pathway. MethodsIn this research, we investigated the effects of BBR on the HPA-axis pathway-related indicators and expression of skeletal muscle glucose transporter 4 (GLUT4) in the high-fat diet and streptozotocin-induced T2DM rats, and identify its possible mechanism of improving IR in T2DM.ResultsBBR significantly reduced fasting blood glucose, total cholesterol, and low-density lipoprotein cholesterol in model rats. It also improved the abnormalities of the high-density lipoprotein cholesterol, the insulin resistance index, the insulin sensitivity index, glucagon, and insulin levels. BBR decreased levels of hypothalamic Orexin-A, the OX2R receptor, the corticotropin-releasing hormone, the pituitary and the plasma adrenocorticotropic hormone, as well as serum and urine corticosterone. At the same time, BBR increased mRNA and protein expressions of GLUT4 in skeletal muscles of model rats as well.ConclusionThose results suggested that BBR can exert inhibition on the HPA-axis and increased skeletal muscle expression of GLUT4 proteins, which may be one of the important mechanisms in BBR to improve IR and regulating glucose and lipid metabolism in T2DM rats.

Effects of exenatide therapy on insulin resistance in the skeletal muscles of high-fat diet and low-dose streptozotocin-induced diabetic rats

Purpose: The glucagon-like peptide (GLP)-1 agonist exenatide shows the same multiple effects on glucose homeostasis as native GLP-1, which can reduce blood glucose levels in individuals with type-2 diabetes mellitus (T2DM). However, its underlying action mechanism on glucose metabolism in the skeletal muscle of T2DM cases is unknown. We investigated the effects and action mechanisms of exenatide on insulin resistance (IR) in the skeletal muscle of high-fat diet and low-dose streptozotocin-induced T2DM rats. Methods: Four groups of Sprague–Dawley rats were studied: non-T2DM (control, C); non-T2DM + exenatide (C + E); T2DM (D); and T2DM + exenatide (D + E). After eight weeks, isotope-tracer methodology was applied to measure the total rate of appearance (Ra) of glucose and glucose infusion rate (GIR) using a hyperinsulinemic–euglycemic clamp with 3-3H-glucose infusion. Glucose uptake in gastrocnemius muscles was determined by measuring 2-deoxy-D-14C-glucose radioactivity. Simultaneously, ultrastructural changes in the cells of gastrocnemius muscles were studied. Results: In the D + E group, body weight and levels of fasting plasma glucose, triglyceride, total cholesterol, low-density lipoprotein and insulin were decreased significantly (p < 0.01) compared with the D group. The Ra of glucose (94.70 ± 13.46 versus 121.07 ± 16.55 μmol/kg/min) was decreased (p < 0.01), whereas the exogenous GIR (144.68 ± 11.03 versus 114.50 ± 9.40 μmol/kg/min) and glucose uptake in muscle (0.24 ± 0.02 versus 0.17 ± 0.02 μmol/g/min) were increased markedly (p < 0.01). Ultrastructural observations revealed that exenatide attenuated the effect of swollen mitochondrial and endoplasmic reticulum within the cells of the skeletal muscle of T2DM rats. Conclusions: These data suggest that exenatide can significantly improve insulin sensitivity in skeletal muscle by increasing glucose uptake in T2DM rats.

Blunted sensitivity of intracardiac ganglion neurons to nicotine in type‐2 diabetic rats

Acetylcholine, a principal excitatory neurotransmitter at the intracardiac ganglionic synapse, acts on the nicotinic acetylcholine receptors (nAChRs) and induces the cell excitation in intracardiac ganglion (ICG) neurons. Our previous study showed that ICG neuron excitability was lowered by the decreased Ca2+ currents in high‐fat diet/low‐dose streptozotocin‐induced type‐2 diabetes mellitus (T2DM) rats. In the present study, we examined the effect of nicotine (a nAChR agonist) on Ca2+ currents and cell excitability in ICG neurons from sham and T2DM rats. Immunofluorescence data showed that there was no significant difference on the protein expression of nAChRs in ICG neurons from sham and T2DM rats. Using whole‐cell patch clamp technique, we found that nicotine concentration‐dependently increased ICG neuron excitation (action potential frequency) and the sensitivity of ICG neuron to nicotine in diabetic rats was lower than that in sham rats (EC50 value is 2.86 μM in T2DM rats and 0.48 μM in sham rats). Diabetes also decreased the response of Ca2+ channels to nicotine in ICG neurons, compared to sham rats. In addition, nicotinic receptor antagonist (100 μM hexamethonium) completely blocked the effect of nicotine on ICG neuron excitability and Ca2+ currents in sham and T2DM rats. Our results indicate that T2DM decreases the sensitivity of ICG neurons to nicotine.