Primary study on the hypoglycemic mechanism of 5rolGLP-HV in STZ-induced type 2 diabetes mellitus mice

Exploring the Oxidative Stress Regulation of Mice with Hyperglycemia by Lactiplantibacillus plantarum SCS4

The aim of this study was to evaluate the effects of Lactiplantibacillus plantarum SCS4 (L. plantarum SCS4) on oxidative stress in streptozocin-induced hyperglycemic mice. After establishment of the hyperglycemic model, control group mice were gavaged daily with phosphate-buffered saline, while different experimental groups (AG, BG, and CG) mice were gavaged with L. plantarum SCS4 suspension, cellular inclusion suspension, and inactivated inclusion suspension for 10 weeks, respectively. Compared with the model group (MG) group, the results showed that fasting blood glucose levels in BG and CG groups decreased, and postprandial 2-h blood glucose levels in BG groups decreased, whereas glucose tolerance improved. Meanwhile, ROS and MDA levels in serum of AG mice were decreased significantly (P < 0.05). Compared with the MG group, serum levels of GPx, HO-1, and NQO1 were increased in the BG group, whereas serum levels of CAT, HO-1, and GSH were increased in the CG group. Our results indicate that L. plantarum SCS4 can alleviate oxidative stress induced by hyperglycemia, and there may be synergistic effects among the different treatments.

Islet MC4R Regulates PC1/3 to Improve Insulin Secretion in T2DM Mice via the cAMP and β-arrestin-1 Pathways

Melanocortin-4 receptor (MC4R) plays an important role in energy balance regulation and insulin secretion. It has been demonstrated that in the pancreas, it is expressed in islet α and β cells, wherein it is significantly correlated with insulin and glucagon-like peptide-1 (GLP-1) secretion. However, the molecular mechanism by which it regulates islet function is still unclear. Therefore, in this study, our aim was to clarify the signaling and target genes involved in the regulation of insulin and GLP-1 secretion by islet MC4R. The results obtained showed that in islet cells, the expression of prohormone convertase 1/3 (PC1/3), which is correlated with islet GLP-1 and insulin secretion, increased significantly under the action of the MC4R agonist, NDP-α-MSH, but decreased under the action of the MC4R antagonist, AgRP. Additionally, we observed that to exert their regulatory functions in the islets, cAMP and β-arrestin-1 acted as important signaling mediators of MC4R, and compared with control islets, the cAMP, PKA, and β-arrestin-1 levels corresponding to NDP-α-MSH-treated islets were significantly elevated; however, in AgRP-treated islets, their levels decreased significantly. Islets treated with the PKA inhibitor, H89, and the ERK1/2 inhibitor, PD98059, also showed significant decreases in PC1/3 expression level, indicating that the cAMP and β-arrestin-1 pathways are significantly correlated with PC1/3 expression. These findings suggest that islet MC4R possibly affects PC1/3 expression via the cAMP and β-arrestin-1 pathways to regulate GLP-1 and insulin secretion. These results provide a new theoretical basis for targeting the molecular mechanism of type 2 diabetes mellitus.

Exploring the antioxidant effect of Lactobacillus plantarum SCS2 on mice with type 2 diabetes

This study aimed to evaluate the antioxidant effect of Lactobacillus plantarum SCS2 (L. plantarum SCS2). After 1 week of acclimation, 120 male KM mice were divided into normal group (NG), model group (MG), solvent control group (KG), and different test groups (TG1, TG2, TG3) (n = 20/group) randomly. In the second week, except NG mice, other mice were given 0.2 ml 50 mg/kg (body weight) streptozocin (STZ) through intraperitoneal injection for 5 days. After successful modeling, NG and MG mice were fed normally, KG mice was given 0.5 ml 0.1 mol/L phosphate buffer saline (PBS) per day, TG1, TG2, and TG3 mice were given 0.5 ml suspension, intracellular content and heat-killed intracellular content of L. plantarum SCS2 per day for 9 weeks. Body weight and blood glucose were observed and recorded during intragastric administration. Glucose tolerance levels were measured at the twelfth week, then mice were sacrificed and the serum was collected to measure insulin (INS), glycosylated hemoglobin (HbA1c), malondialdehyde (MDA), reactive oxygen species (ROS) and antioxidant enzymes. The results showed that the reduction of weight loss in TG1 and TG2 mice was observed, which was consistent with the blood glucose. At the same time, the INS level of TG1, TG2, and TG3 mice were increased and the HbA1c levels were decreased. Otherwise, the MDA and ROS content in the serum of TG1, TG2, and TG3 mice were decreased and the level of antioxidant enzymes was increased. Interestingly, the activity and content of antioxidant enzymes in TG2 group was the highest in the three test groups. PRACTICAL APPLICATIONS: The results of this study showed that L. plantarum SCS2 could effectively reduce blood glucose, relieve weight loss, improve INS deficiency, and also improve oxidative stress by increasing the activity of antioxidant enzymes. The findings suggest that L. plantarum SCS2 could improve diabetes-related symptoms by alleviating oxidative stress. In the future, people could promote the application of lactic acid bacteria (LAB) which is found in traditional foods with the ability of improving oxidative damage in food nutrition and related fields, so as to guide residents to form good dietary habits, and effectively prevent type 2 diabetes. Meanwhile, it also can enhance the edible value of traditional foods.