Rhodiola crenulata root ameliorates derangements of glucose and lipid metabolism in a rat model of the metabolic syndrome and type 2 diabetes

Ethnopharmacological relevance: Rhodiola species are traditionally used as tonics and stimulants to treat asthenia, suggesting their possible regulatory effect on energy metabolism. Clinical trials have demonstrated their glucose-lowering effect in type 2 diabetes. Aim of the study: To examine the effects of Rhodiola on glucose and lipid metabolism in the metabolic syndrome and type 2 diabetes. Materials and methods: Zucker diabetic fatty (ZDF) rats were treated with Rhodiola crenulata root (RCR) powder (100 and 500 mg/kg, by gavage, once daily for 4 weeks). In addition, the effects of RCR on sucrose-induced acute hyperglycemia in mice and olive oil-induced hypertriglyceridemia in rats were also examined. Biochemical variables were determined enzymatically or by ELISA. Results: In ZDF rats, RCR treatment decreased the increased plasma insulin and triglyceride concentrations at baseline, the index of the homeostasis model assessment of insulin resistance (HOMA-IR) and excessive hepatic triglyceride accumulation. This treatment also inhibited abnormal increases in plasma glucose and insulin concentrations during oral glucose tolerance test. Furthermore, RCR reversed the increased adipose insulin resistance index, and accelerated the decline of plasma concentrations of non-esterified fatty acids after exogenous glucose stimulation. However, RCR minimally affected sucrose-induced acute hyperglycemia in mice and olive oil-induced acute hypertriglyceridemia in rats. Conclusions: The present results demonstrate that RCR treatment improves metabolic derangements in animal model of the metabolic syndrome and type 2 diabetes. Our findings may provide new pharmacological basis of therapeutics for the adaptogenic plants to treat metabolic derangements-associated disorders, such as asthenia. (C) 2012 Elsevier Ireland Ltd. All rights reserved.