The gut microbiota confers the glucose-and lipid-lowering effect of Laurolitsine in db/db mice

Abstract Background Modulations on gut microbiota by traditional Chinese medicines (TCMs) and their active components are emerging as potential therapeutic agents on diabetes. Litsea glutinosa is a TCM used in clinic to treat diabetes with alkaloids as the active constituents, and the Laurolitsine is the richest one. Purpose Based on that, this study was designed to identify the potential capability of Laurolitsine on alleviating Type 2 diabetes and the changes of the composition of intestinal flora related to this disease. Methods In present study, Laurolitsine was administered to diabetic mice (db/db) by daily oral gavage at doses of 50, 100 and 200 mg/kg/day for 4 weeks. The body weight, fasting blood glucose, oral glucose tolerance test (OGTT) and insulin tolerance test (ITT), lipid metabolism of serum and liver and liver function were measured to assess the anti-hyperglycemic and anti-hyperlipidemic effects of Laurolitsine. The liver pathological changes were observed by HE staining. Meanwhile, the effects of Laurolitsine on the changes of the composition of gut microbiota in mice were investigated via metagenomic analysis. Results Experimental results show that different doses of Laurolitsine have varying degrees of hypoglycemic and hypolipidemic effects. Among them, the treatment effect of 200mg·Kg-1 is the most obvious. In addition, Laurolitsine changes the structure of intestinal microflora significantly at various taxonomical levels in the diabetic db/db mice. Conclusions These results demonstrate that Laurolitsine may regulate glucose and lipid metabolism and improve diabetes through modulating intestinal microflora of Parabacteroides and Mucispirillum, which may be acknowledged as the iconic bacteria of diabetes.