Protective role of nano-selenium-enriched Bifidobacterium longum in delaying the onset of streptozotocin-induced diabetes.

Bifidobacterium longum (B. longum) could accumulate Selenium (Se) and nano-Se in the form of Se-B. longum and Nano-Se-B. longum, respectively. In this study, the effect of Nano-Se-B. longum in diabetic mice was evaluated. Physiological and metabolic parameters such as blood glucose, body weight, serum insulin level, intraperitoneal glucose tolerance test (IPGTT), food intake, water consumption and urine output were evaluated. The expression of insulin signalling pathway-related proteins was evaluated by western blotting. Haematoxylin and eosin (H&E) was used for histological examination of the liver, pancreas and kidney sections. Creatinine levels in serum (SCr) and blood urea nitrogen (BUN) were measured. Nano-Se-B. longum was the best in terms of delaying the onset of diabetes. Nano-Se-B. longum decreased blood glucose and body weight compared with those noted for the model group. IPGTT, food intake, water consumption and urine output significantly increased and serum insulin levels significantly decreased in the model group compared with those in all the Nano-Se-B. longum-treated mice. Histological results showed that the Nano-Se-B. longum-treated mice were better than the model group mice in terms of pathological changes. The expression of insulin signalling pathway-related proteins was upregulated in the Nano-Se-B. longum-treated groups. A significant increase in SCr and BUN levels was noted in the model group. This study for the first time reported the dose-dependent preventive effect of Nano-Se-B. longum on the onset of diabetes and renal damage. The mechanism may be related to changes in insulin signalling.