Insulin Increases Viability of Neurons in Rat Cerebral Cortex and Normalizes Bax/Bcl-2 Ratio under Conditions of Oxidative Stress.

We studied the protective effect of insulin in various concentrations and its effect on the Bax/ Bcl-2 ratio in neurons of rat cerebral cortex under conditions of oxidative stress. The protective effect of insulin was dose-dependent within the nanomolar range (1 nM<10 nM<100 nM). Preincubation with insulin in concentrations of 100 nM and 1 μM significantly increased Bcl-2 content in neurons in 5, 30, and 45 min and 1, 2, and 4 h after the start of cell exposure to H2O2. This prooxidant increased the Bax/Bcl-2 ratio in neurons to 141-164% in comparison with the control (100%); preincubation of neurons with insulin returned this ratio to normal.