Beneficial effects of Ginkgo biloba extract on insulin signaling cascade, dyslipidemia and body adiposity of diet-induced obese rats

• Grant number: 14/07424-3
• Support Opportunities: Regular Research Grants - Publications - Scientific article
• Start date: June 01, 2014
• End date: November 30, 2014
• Field of knowledge: Biological Sciences - Pharmacology
• Principal Investigator: Monica Marques Telles
• Grantee: Monica Marques Telles
• Host Institution: Instituto de Ciências Ambientais, Químicas e Farmacêuticas (ICAQF). Universidade Federal de São Paulo (UNIFESP). Campus Diadema. Diadema , SP, Brazil

Abstract

Ginkgo biloba extract (GbE) has been pointed as an efficient medicine for diabetes mellitus type 2 treatment. It remains unclear whether its effects are due to an improvement of insulin signaling cascade, especially in obese subjects. The aim of the present study was to evaluate the effect of GbE on insulin tolerance, food intake, body adiposity, lipid profile, fasting insulin and muscle levels of IRS-1, PTP-1B, Akt and Akt phosphorylation on diet-induced obese rats. Rats were fed with high-fat diet (HFD) or normal fat diet (NFD) during 8 weeks. After that, HFD group was divided into two groups: rats gavaged with saline (vehicle) (HFD+V) and rats gavaged with 500 mg/Kg of GbE (HFD+Gb). Normal-Fat Diet (NFD) rats were gavaged with vehicle. At the end of treatment, rats were anesthetized, insulin was injected in the portal vein and after 90 seconds, gastrocnemius muscle was removed. The quantification of IRS-1, Akt and Akt phosphorylation were performed by Western blotting technique. Serum levels of fasting insulin and glucose, triacylglycerols and total cholesterol and fractions were measured. Insulin tolerance test was also performed. It can be seen that hyperlipidic diet ingestion promoted loss of insulin sensitivity and also resulted in significant increase of body adiposity, plasma triacylglycerol and glucose levels. In addition, GbE treatment significantly reduced food intake and body adiposity while it protected against hyperglycemia and dyslipidemia in DIO rats. It also enhanced insulin sensitivity in comparison to HFD+V rats while restored insulin-induced Akt phosphorylation, increased IRS-1 and reduced PTP-1B levels in gastrocnemius muscle. The present findings suggest that Ginkgo biloba might be efficient to prevent and treat the obesity-induced insulin signaling impairment. (AU)