PERINATAL ALTERATIONS OF THYROID-HORMONES AND BEHAVIOR IN ADULT-RATS

Several studies have shown the relevance of the neuroendocrinological system in the development and function of the nervous system. In order to observe the influence of thyroid hormones during development on th e behaviour of adult rats we induced dysthyroid states during the peri natal period. Results indicate that some behaviours are more susceptib le to the action of thyroid hormones than others. We observed that the thyroid hormone deficiency causes an increase of activity in animals in spite of a large period of rehabilitation. Thyroxine-treated rats s howed an anxiogenic behavioural pattern in the elevated plus-maze, whi le animals rehabilitated from perinatal, deficit of thyroid hormones s howed an anxiolitic pattern. These findings suggest that an excess of thyroid hormones has less effect on behaviour than a deficiency of the se hormones.