Abstract
ABSTRACT Several drugs from the morphine, pethidine and morphinan series were evaluated with respect to their action on the pituitary secretion of thyrotrophin (TSH). This action was measured by the release and the uptake of 131I by the thyroid gland of mice. Daily administration of 500 μg of morphine, codeine, dihydromorphinone, levorphan, dextrorphan or meperidine significantly depressed the uptake of 131I by the thyroid gland within five days. Single injections of 500 μg of either dihydromorphinone or levorphan increased the thyroidal uptake of 131I The thyroids of hypophysectomized mice, pretreated with 131I and thyroxine, failed to respond to injections of these drugs. Daily administration of these drugs for five days failed to change pituitary content of TSH from the control level, or to effect a change in the turn-over rate of exogenous radiothyroxine. These results suggest that these drugs do not exert direct action on the thyroid but act on thyroid function through their effect on the hypothalamus-pituitary axis.
