Abstract
AIMS: Effects of insulin and ascorbic acid on expression of Bcl-2 family proteins and caspase-3 activity in hippocampus of diabetic rats were evaluated in this study. METHODS: Diabetes was induced in Wistar male rats by streptozotocin (STZ). Six weeks after verification of diabetes, the animals were treated for 2 weeks with insulin or/and ascorbic acid in separate groups. Hippocampi of rats were removed and evaluation of Bcl-2, Bcl-x(L), and Bax proteins expression in frozen hippocampi tissues were done by SDS-PAGE electrophoresis and blotting. The Bcl-2, Bcl-x(L), and Bax proteins bands were visualized after incubation with specific antibodies using enhanced chemiluminescences method. Caspase-3 activity was determined using the caspase-3/CPP32 Fluorometric Assay Kit. RESULTS: Diabetic rats showed increase in Bax protein expression and decrease in Bcl-2 and Bcl-x(L) proteins expression. The Bax/Bcl-2 and Bax/Bcl-x(L) ratios were found higher compared with non-diabetic control group. Treatments with insulin and/or ascorbic acid were resulted in decrease in Bax protein expression and increase in Bcl-2 and Bcl-x(L) proteins expression. The Bcl-2/Bax and Bcl-x(L)/Bax ratios were found higher in treated groups than untreated diabetic group. Caspase-3 activity level was found higher in diabetic group compared with non-diabetic group. Treatment with insulin and ascorbic acid did downregulated caspase-3 activity. CONCLUSIONS: Our data provide supportive evidence to demonstrate the antiapoptotic effects of insulin and ascorbic acid on hippocampus of STZ-induced diabetic rats.