Effects of the ethanol extract of the roots of Brassica rapa on glucose and lipid metabolism in C57BL/KsJ- db/db mice

Abstract

The antidiabetic efficacy of turnip (Brassica rapa) roots ethanol extract (TE) was investigated in type 2 diabetic animals. C57BL/KsJ-db/db (db/db) mice and db/+ mice were used and the db/db mice were divided into control, TE (0.26 g/100g diet) and rosiglitazone (RG, 0.005 g/100g diet) groups. Despite hyperinsulinemia, the glucokinase activity was lower in the liver of the db/db mice than the db/+ mice, while the glucose-6-phosphatase activity was higher. TE and RG improved the glucose and insulin tolerance and lowered the blood glycosylated hemoglobin, plasma insulin, C-peptide and glucagon levels as well as reversed these hepatic glucose regulating enzyme activities in db/db mice. TE also increased the insulin/glucagon ratio and hepatic glycogen content. The plasma free fatty acid and plasma and hepatic cholesterol and triglyceride levels were higher in the db/db mice than db/+ mice. Interestingly, TE and RG lowered these plasma and hepatic lipids, and simultaneously reduced the hepatic phosphatidate phosphohydrolase, HMG-CoA reductase, ACAT, beta-oxidation and carnitine palmitoyl transferase activities. Furthermore, TE lowered the hepatic fatty acid synthase activity, hepatic lipid droplets accumulation, and adipose tissue weight and size. We suggest TE may exert an antidiabetic effect in type 2 diabetic mice by enhancing the glucose and lipid metabolism.