Effect of perinatal triiodothyronine (T3) treatment on thymic glucocorticoid and estrogen receptors and uterus estrogen receptors. Receptor selectivity during hormonal imprinting.

Triiodothyronine (T3) treatment at 1, 3 and 5 days after birth significantly increased the binding capacity (density) of the thymus glucocorticoid receptor of male and female rats in adult age. There was no change in the binding capacity of uterine and thymic estrogen receptors. The experiments point to the sensitivity of developing hormone receptors and call the attention to the possibility of overlap between the members of the steroid receptor superfamily at the perinatal critical period. This overlap is not dependent on the structure of the hormone, however it is dependent on the structure of receptors and acceptors. The difference in the reaction of glucocorticoid and estrogen receptors shows the differences in the sensitivity of receptors to false imprinting.