The effects of separate and concurrent Lactobicillus plantarum and inulin supplementation on serum levels of metabolic factors and leptin, and anxiety-related behavior disorders in male rats with type 2 diabetes

Abstract

Backgroand: Type 2 diabetes mellitus (T2DM) is a common metabolic disease, characterized by insulin resistance (IR) and insulin deficiency. Hyperglycemia could cause brain damage and undesirable effects on the growth and development of neuronal cells. In this regard, the beneficial effects of prebiotics or probiotics have been reported in diabetes, but there are limited studies of their effects on brain activity. Therefore, due to the high prevalence of T2DM and its subsequent complications, including anxiety and depression disorders and their adverse effects, and on the other hand due to the beneficial effects of probiotics and synbiotics in diabetes and cognitive behavioral disorders, the aim of this study was to determine the effect of Lactobacillus plantarum (L.plantarum), inulin and their synbiotic composition on serum levels of metabolic and leptin parameters and anxiety disorders in type 2 diabetic rats. Materials and Methods: This study was performed on 35 male Wistar rats for 8 weeks, divided into 6 groups. T2DM was induced by high-fat diet (HFD) for 4 weeks and then intraperitoneal injection of streptozotocin (STZ) (35 mg/ kgBW). L.plantarum was given daily to the rats at a concentration of 107 colony units per ml (CFU/ ml) for 8 weeks. Inulin was also administered based on 5% of the daily food intake of the rats and was dissolved in drinking water of each cage. At the end of the intervention, the elevated plus maze (EPM) test was performed. After anesthesia, the blood sample was removed for measurement of parameters, using ELISA method Results: Serum glucose level in the DL, DI, and DLI groups was decreased compared with the DC and DSh groups. Synbiotic increased serum levels of insulin compared to the DSh group (p=0.013). Prebiotic and synbiotic increased serum level of leptin in comparison to the DC group (p <0.05, and p <0.01, respectively). Also, Synbiotic improved lipid profiles compared with DC and DSh groups. TG (p <0.01 and p <0.001, respectively) and VLDL-C (p <0.01 and p <0.001, respectively) were decreased significantly in the probietic and synbiotic groups. In contrast, HDL-C was increased significantly in the synbiotic group compared with the DC group (p <0.05). Furthermore, beneficial effects were observed on elevated plus maze test. The results of this study indicated that L.plantarum, inulin, or a combination of them in T2DM could improve the metabolic status and improve the function of the hypothalamus. Conclusion: L.plantarum and inulin could have beneficial effects in metabolic status of the disease through improving IR and hyperlipidemia and decrease the complications of the disease, including behavioral disorders associated with anxiety. Furthermore, the results suggested that the use of synbiotic had more significant effects than probiotic and prebiotics in the improvement of T2DM complications.