Symplocos cochinchinensis enhances insulin sensitivity via the down regulation of lipogenesis and insulin resistance in high energy diet rat model

摘要

Ethnopharmacological relevance: This plant has been utilized in Indian system of medicine for treatment of diabetes. This is clearly evident from the composition of Ayurvedic preparation for diabetes 'Nisakathakadi Kashayam' where this is one of the main ingredients of this preparation Aim of the study: The study aims in elucidating the molecular mechanisms underlying the insulin sensitizing effects of Symplocos cochinchinensis ethanol extract (SCE) using a high fructose and saturated fat (HFS) fed insulin resistant rat model. Materials and methods: Experimental groups consisted of normal diet (ND), ND+SCE 500 mg/kg bwd, HFS +vehicle, HFS+metformin 100 mg/kg bwd, HFS+SCE 250/500 mg/kg bwd. Initially the animals were kept under HFS diet for 8 weeks, and at the end of 8 week period, animals were found to develop insulin resistance and dyslipidemia. Post-administration of SCE, metformin or vehicle were carried out for 3 weeks. Gene and protein expressions relevant to insulin signalling pathway were analysed. Results: HFS significantly altered the normal physiology of animals via proteins and genes relevant to metabolism like stearoyl-CoA desaturase (SCD1), sterol regulatory element binding protein 1 (SREBP-lc), fatty acid synthase (FAS), glucose 6 phosphatase (G6Pase), phosphoenol pyruvate carboxykinase (PEPCK), glucose transporter 2 (GLUT2), protein tyrosine phosphatse 1B (PTP1B), peroxisome proliferator activated receptor alpha (PPAR alpha), sirtuin 1 (SIRT1) and glucokinase. SCE administration attenuates the insulin resistance in HFS rat by the down regulation of SCD1 gene expression that modulates SREBP-lc dependent and independent hepatic lipid accumulation. Conclusion: SCE enhances insulin sensitivity via the down regulation of lipogenesis and insulin resistance in HFS rat model.