Rui Zhao - Department of Pharmaceutical Engineering, College of Life Science & Biotechnology, Heilongjiang August First Land Reclamation University, Daqing High-Tech Industrial Development Zone, China
Xu Gao - Department of Biochemistry and Molecular Biology, Basic Medical Science College, Harbin Medical University, Harbin China
Tao Zhang - School of Basic Medical Sciences, Jiamusi University, No.۱۸۸ Xuefu Street, Jiamusi City, Heilongjiang Province, China
Xing Li - Department of Nephrology, Daqing people’s Hospital, No.۲۱۳ Jianshe Road, Gaoxin District, Daqing City, Heilongjiang Province, China

Objective(s): Type ۲ diabetes mellitus (T۲DM) is associated with circadian disruption. Our previous experimental results have showed that dietary Lycium barbarum. polysaccharide (LBP-۴a) exhibited hypoglycemic and improving insulin resistance (IR) activities. This study was to explore the mechanisms of LBP-۴a for improving hyperglycemia and IR by regulating biological rhythms in T۲DM rats. Materials and Methods:The rats of T۲DM 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-۴a on mRNA expression of melatonin receptors (MT۲) in epididymal adipose tissue was evaluated by RT-PCR. The expression of CLOCK and BMAL۱ in pancreatic islet cells was detected by Western blotting. Results: Our data indicated that the ۲۴-hr rhythm of blood glucose appeared to have consistent with normal rats after gavaged administration of LBP-۴a for each day of the ۴ weeks, and the effects of hypoglycemia and improving hyperinsulinemia in T۲DM rats treated at high dose were much better than that at low dose. The mechanisms were related to increasing MT۲ level in epididymal adipose tissue and affecting circadian clocks gene expression of CLOCK and BMAL۱ in pancreatic islet cells. Conclusion: LBP-۴a administration could treat T۲DM rats. These observations provided the background for the further development of LBP-۴a as a potential dietary therapeutic agent in the treatment of T۲DM.

Circadian clocks, Lycium barbarum, Melatonin receptors, Polysaccharide, Type ۲ diabetes mellitus