MORPHOMETRIC AND IMMUNOHISTOCHEMICAL ANALYSIS OF THE BRAIN AND LIVER OF HYPOTHYROIDISM induced rats treated with melatonin
Hypothyroidism, brain, melatonin, rats, morphometry, oxidative stress
It is known that pregnancy influences several maternal physiological changes, one of which is thyroid function. The role of thyroid hormones and their importance during the gestational period have become a subject of great interest, as has their influence on the maternal nervous system. Melatonin is an important neurohormone that plays a role in thyroid regulation and plays a significant role in pregnancy. Thus, we tested the hypothesis that exogenous melatonin can decrease or prevent the effects of hypothyroidism in the rat brain. Fifteen pregnant rats were divided into 3 groups: GC: rats without induction of hypothyroidism; GH: rats induced to hypothyroidism; GHM: hypothyroidism-induced rats treated with melatonin. Hypothyroidism was induced by oral administration of propitiouracil (1mg/animal) and melatonin was administered subcutaneously (10mg/kg). Animal weight, brain weight, organosomatic index, hormone levels of T3 and T4, morphometry, oxidative stress, as well as histochemistry and histopathology of the frontal cortex were analyzed. The results showed the confirmation of hypothyroidism in the rats of the untreated group by the significant increase in the level of TSH when compared to the control group and treated with melatonin. Females in the hypothyroidism group showed weight gain compared to the melatonin-treated group, however, there was a significant decrease in brain weight and organosomatic index. In addition, the females that were treated with melatonin showed favorable results regarding the reduction of nissl bodies, the reduction in the number of neurons in the cortex, lipid peroxidation and reduced glutathione in relation to the group of rats with hypothyroidism. Thus, we conclude that treatment with melatonin may be an effective strategy to prevent the effects of hypothyroidism on the frontal cortex of the brain.