Abstract
In this paper, we investigated the effects of Coptis chinensis polysaccharide (CCP) on hyperglycemia and glucose intolerance in high-fat diet (HFD)-induced diabetic C57BL/6J mice. CCP was prepared by extraction from Coptis chinensis and oral given to the mice. C57BL/6J mice in each of the 5 groups (eight mice per group) were given either the normal diet (ND) (D12450B, 10% kcal% fat; Research diet, New Brunswick, NJ, USA), HFD (D12451, 45% kcal% fat; Research diet, New Brunswick, NJ, USA), or HFD with CCP of differing hardness (500, 1000, and 2000ppm) for 20 weeks. Mice given an HFD with CCP showed lowered fasting plasma glucose levels compared to HFD-fed mice. Oral and intraperitoneal glucose tolerance tests showed that CCP improves impaired glucose tolerance in HFD-fed mice. Histopathological evaluation of the pancreas showed that CCP recovers the size of the pancreatic islets of Langerhans, and increases the secretion of insulin and glucagon in HFD-fed mice. Quantitative reverse transcription polymerase chain reaction results revealed that the expression of hepatic genes involved in glucogenesis, glycogenolysis and glucose oxidation were suppressed, while those in glucose uptake, β-oxidation, and glucose oxidation in muscle were increased in mice fed HFD with CCP. CCP increased AMP-dependent kinase (AMPK) phosphorylation in 3T3-L1 pre- and mature adipocytes and improved impaired AMPK phosphorylation in the muscles and livers of HFD-induced diabetic mice. CCP stimulated phosphoinositol-3-kinase and AMPK pathway-mediated glucose uptake in 3T3-L1 adipocytes. Taken together, these results suggest that CCP has potential as an anti-diabetic agent, given its ability to suppress hyperglycemia and improve glucose intolerance by increasing glucose uptake.