DIABETES INDUCED BY STREPTOZOTOCIN CAUSES REDUCED NA-K ATPASE IN THE BRAIN

Na-K ATPase activity in the brain decreased significantly after diabetes was induced with streptozotocin in rats. Largest decreases were observed in the hippocampus (-30%) and the cerebral cortex (-26%). Smaller decreases were observed in the thalamus (-13%), hypothalamus (-11%) and brain stem (-10%). Na-K ATPase activity in the striatum and the cerebellum were not significantly decreased. The varied decreases suggest that the regional variation of the enzyme is enhanced in the diabetic state. The enzymes of glucose metabolic pathway, namely hexokinase, lactate dehydrogenase and citrate synthase in the brain regions largely remained unchanged although increases in lactate dehydrogenase were observed in some regions. Acetylcholinesterase activity, a marker for the cholinergic system, remains unaltered in the brain during diabetes. The results are discussed with respect to the possible metabolic factors which alter the Na-K ATPase in the brain and its comparison with the peripheral nerve.