The antilipolytic action of bis(alpha-furancarboxylato)oxovanadium(IV) in adipocytes

Abstract

Background: Previously, bis(alpha-furancarboxylato)oxovanadium(IV)(BFOV) exhibited potent hypoglycemic activity in diabetic animals. We evaluated the effects of BFOV on lipolysis in isolated rat adipocytes and lipid metabolism in fat-fed/streptozotocin (STZ)-induced diabetic rats, an animal model of type 2 diabetes.

Methods: Antilipolytic action of BFOV was investigated by observing free fatty acids (FFA) release in isolated rat adipocytes treated with epinephrine and forskolin. Diabetic rats were induced by high-fat feeding plus STZ injection (25 mg/kg, i.p.). The rats were randomly divided into non-diabetic, diabetic, diabetic-BFOV (0.02, 0.06 and 0.2 mmol/kg) and diabetic-vanadyl sulfate group. All substances were given intragastrically to rats for 4 weeks. The concentrations of blood glucose, serum lipid and leptin, as well as body weight and food intake were determined.

Results: FFA release from adipocytes treated with epinephrine was markedly inhibited by BFOV and vanadyl sulfate, with the IC(50) values of 0.30+/-0.20 and 0.46+/-0.26 mmol/l, respectively, but not by insulin. Whereas, the inhibition of vanadyl compounds on FFA release triggered by forskolin in adipocytes were not observed. BFOV dose-dependently reduced serum triglycerides and FFA concentrations when compared with untreated diabetic rats (P<0.05), while it did not influence cholesterol concentrations, similar to vanadyl sulfate. Serum leptin concentration was also decreased both in the BFOV- and vanadyl sulfate-treated diabetic group (P<0.05). Moreover, BFOV markedly reduced blood glucose concentration and food intake (P<0.05), but it did not change the body weight of diabetic rats.

Conclusion: BFOV has an antilipolytic action in adipocytes mediated by catecholamines. This action was distinct from that of insulin and also not related to inhibiting the activity of adenylate cyclase. In vivo, BFOV could improve dyslipidemia and leptin sensitivity in fat-fed/STZ-diabetic rats.