The Effects of Hypo- and Hyperthyroidism on Glucose 6-Phosphate Dehydrogenase Activities in Regions of Rat Brain

The variations of glucose 6-phosphate dehydrogenase (G6PD) activity in different brain regions of normal, hypo- and hyperthyroid rats were investigated. Hypo- and hyperthyrodism were experimentaly induced by administration of methimazol and liothyronine, respectively. In normal rats, midbrain had the minimum (70 mU/mg) and cerebral cortex the maximum (349 mU/mg) G6PD activity. Hyperthyrodism increased the enzime activities in straitum (72%) and midbrain (144 %). Hypothyrodism also elevated G6PD activities in the two above regioins but to a lesser extent. The enzyme activities were decreased by hypothyrodism in hypothalamus (73%) and cerebellum (45%). Hyperthyrodism, however, increased G6PD activities in cerebellum by (16%) but did not significantly change the enzyme activity in hypothalamus. Neither hypo- nor hyperthyrodism affected cerebral cortex G6PD activity. The data suggest that the changes in G6PD activities of the brain regions may have been occured via different thyroid hormone effect on the regions