Decreased GABA receptor binding in the cerebral cortex of insulin induced hypoglycemic and streptozotocin induced diabetic rats.

Hypoglycemia is the major problem to blood glucose homeostasis in treatment of diabetes and is associated with severe irreversible consequences including seizures, coma and death. GABAergic inhibitory function in the cerebral cortex plays an important role in controlling the excitability and responsiveness of cortical neurons. Present study analysed effects of insulin induced hypoglycemia and streptozotocin induced diabetes on the cortical GABA receptor binding, GABA(Aά1), GABA(B) receptor subtype expression, GAD and GLUT3 expression. Diabetic rats showed decreased [(3)H] GABA binding in the cerebral cortex compared to control while hypoglycemia exacerbated the decrease. GABA receptor subunits; GABA(Aά1), GABA(B) and GAD expression significantly decreased in diabetic rats whereas hypoglycemia significanly decreased the expression compared to diabetic. GLUT3 expression significantly up regulated during both hypo and hyperglycemia. Our results showed that hypoglycemia and hyperglycemia decreased GABAergic neuroprotective function in the cerebral cortex, which account for the increased vulnerability of cerebral cortex to subsequent neuronal damage during hypo/hyperglycemia.