Effect of curcumin on activation and expression of IRS1, Grb2, K-Ras and Bax in STZ-induced diabetic rat brains

Abstract

Aim: Diabetes mellitus leads to development of neuropathy as a secondary complication. The main mechanism of diabetic neuropathy is the dysregulation of energy balance and glucose homeostasis in brain. This study aimed to examine the effects of curcumin as an antidiabetic compound on the expressions of IRS1, Grb2, K-Ras and Bax proteins in diabetic rat brains. Material and Methods: 16 Wistar albino rats were divided randomly into four groups as: control, curcumin; STZ-treated and STZ+Curcumin treated groups. The rats in STZ group were induced to develop diabetes by intraperitoneal administration of STZ. Then, they were treated with curcumin daily by gavage. Expressions and activation of IRS1, Grb2, K-Ras and Bax were determined by western blot analyses. Results: Western blot analyses showed that curcumin treatment increased IRS1 tyrosine phosphorylation and it reversed the negative effect of STZ on IRS1 activation. K-Ras expression significantly decreased while Bax expression increased in STZ group (p<0.05). No significant changes in the expressions of Grb2 and IRS1 were observed for all groups. Conclusion: Based on the results, it could be suggested that curcumin treatment significantly reversed the negative effects of STZ on insulin signaling pathway members in STZ induced diabetic rat brains.