Evidence for the Existence of a Histamine H2-Receptor in the Mouse Thyroid

Abstract

The existence of a histamine H2-receptor in the thyroid was investigated. Histamine in vitro stimulated for formation of cyclic[c]AMP and colloid droplet formation in mouse thyroid lobes. Stimulation by histamine of cAMP formation in mouse thyroid lobes was significantly inhibited by metiamide, a histamine H2-receptor antagonist. 4-Methylhistamine, a histamine H2-receptor agonist, markedly stimulated cAMP formation, whereas 2-methylhistamine, a histamine H1-receptor agonist, was ineffective. The stimulation by 4-methylhistamine of cAMP formation was markedly inhibited by metiamide, but not by chlorpheniramine, a histamine H1-receptor antagonist. Metiamide did not affect cAMP formation induced by TSH [thyrotropin] or by the long-acting thyroid stimulator. There probably exists a histamine H2-receptor in the membranes of the thyroid follicular cells which facilitate thyroid hormone secretion via the adenylate cyclase-cAMP system.