Possible inhibitory role of histamine H2 receptors in the control of basal TSH secretion in male rats: studies with dimaprit, a selective H2 receptor agonist.

Dimaprit,a selective H2 receptor agonist, induced a dose-related decrease of serum TSH basal levels in male rats. This effect was blocked in animals pretreated with cimetidine, a blocker of H2 receptors. Furthermore, dimaprit, added to the anterior pituitary in vitro, failed to induce any change of TSH release. These results are consistent with the hypothesis of an inhibitory role played by H2 receptors located on the median eminence in the control of TSH secretion in male rats.