Effects of Lycium barbarum. polysaccharide on type 2 diabetes mellitus rats by regulating biological rhythms

OBJECTIVE(S): Type 2 diabetes mellitus (T2DM) is associated with circadian disruption. Our previous experimental results have showed that dietary Lycium barbarum. polysaccharide (LBP-4a) exhibited hypoglycemic and improving insulin resistance (IR) activities. This study was to explore the mechanisms of LBP-4a for improving hyperglycemia and IR by regulating biological rhythms in T2DM rats. MATERIALS AND METHODS: The rats of T2DM were prepared by the high-sucrose-fat diets and injection of streptozotocin (STZ). The levels of insulin, leptin and melatonin were measured by enzyme linked immunosorbent assay (ELISA). The effect of LBP-4a on mRNA expression of melatonin receptors (MT2) in epididymal adipose tissue was evaluated by RT-PCR. The expression of CLOCK and BMAL1 in pancreatic islet cells was detected by Western blotting. RESULTS: Our data indicated that the 24-hr rhythm of blood glucose appeared to have consistent with normal rats after gavaged administration of LBP-4a for each day of the 4 weeks, and the effects of hypoglycemia and improving hyperinsulinemia in T2DM rats treated at high dose were much better than that at low dose. The mechanisms were related to increasing MT2 level in epididymal adipose tissue and affecting circadian clocks gene expression of CLOCK and BMAL1 in pancreatic islet cells. CONCLUSION: LBP-4a administration could treat T2DM rats. These observations provided the background for the further development of LBP-4a as a potential dietary therapeutic agent in the treatment of T2DM.