The affect of iodine-induced thyroid blockade on cortisol levels in female rats

Aim: to study the possibility that iodine-induced thyroid blockade affects the functional activity of the adrenals in euthyroid female rats. The experiment involved 30 outbred rats - 6-month-old females weighing 250 ± 30 g. The animals were kept in vivarium under standard light conditions and received standard food and water. The females were taken for experiment in phases of diestrum and metoestrus. 8 animals were included in the control group, 7 - in the second group. The first, third, fourth, fifth, sixth and seventh groups included 3 rats each. The cycling of gonad functioning was analyzed based on examination of vaginal smears. In order to measure the cortisol concentration the animal blood serum was subjected to enzyme-linked immunoassay using the microplate reader (BIO-RAD model 680 MR 12726, USA). Iodine-induced thyroid blockade stimulated the adrenal function in female rats. It is also worth noticing that the normalization of the adrenal status was prior to normalization of thyroid function. Probably, the adrenal glands served a certain purpose in the physiological mechanism of the body reaction to large doses of iodine, including the aspect of stress adaptation. It has been found that iodine-induced thyroid blockade in female rats is combined with the growth of cortisol levels. The rebound effect leads to spontaneous normalization of cortisol levels.