BRAIN CATECHOLAMINE CONCENTRATIONS IN HYPEROSMOLAR DIABETIC AND DIABETIC RATS

The concentrations of brain catecholamines were measured and compared in the experimentally made hyperosmolar diabetic, diabetic and normal control rats in order to clarify the metabolic changes of the brain in these states. Diabetes was induced with streptozotocin and hyperosmolarity was achieved through deprivation of water for 50 hours prior to experimentation. Dopamine, norepinephrine and epinephrine concentrations were measured in the left cerebral cortex, hypothalamic-thalamic area, cerebellum and medulla oblongata. Dopamine and norepinephrine concentrations were significantly elevated in the cerebral cortex, hypothalamic-thalamic area and cerebellum of the dehydrated hyperosmolar-diabetic rats relative to those of normal controls (p < 0.01-0.05). In diabetes with high blood sugar level, the norepinephrine concentration was significantly elevated in the cerebral cortex, cerebellum and medulla oblongata, and these changes generally paralleled the increase in fasting blood glucose. It was concluded that hyperosmolarity due to dehydration contributed these changes. The findings of this study further suggest that changes in brain catecholamines may be involved in the nervous system disturbances that occur in the dehydrated hyperosmolar-diabetes and severe diabetes.