[Interaction between the hypothalamo-hypophyseal system and the thyroid gland during different age periods]

Age peculiarities of interaction of the hypothalamo-hypophysial system and the thyroid gland with consideration to direct and feed-back control were studied. Significant alterations appear in old age in the hypothalamo-hypophysial system and the thyroid gland at the level of direct and feed-back control; there is an increase of sensitivity of the thyroid gland tissue to TSH, and of the hypothalamus-hypophysis--to the T4 effect. This rise of sensitivity is largely determined by the activation of the T4 deiodination processes in the adenohypophysis. The reactive capacity of the thyroid gland and of the hypothalamo-hypophysial complex to the corresponding influence is decreased.