Catecholamine inhibition of thyrotropin-induced secretion of thyroxine: mediation by an alpha-adrenergic receptor.
Thyroxine secretion by mouse thyroid gland incubated in vitro was measured. Thyrotropin or dibutyryl cAMP increased thyroxine secretion several-fold. l-Epinephrine and l-norepinephrine strongly inhibited this stimulated release; l-isoproterenol was relatively ineffective. Phentolamine prevented the inhibition by catecholamines of thyroxine release; l-propranolol had no effect. These findings indicate that stimulation of alpha-adrenergic receptors opposes the action of thyrotropin in the regulation of thyroxine secretion.
D000818:Animals; D000242:Cyclic AMP / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology*; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D051379:Mice; D009638:Norepinephrine / Q000494:pharmacology*; D010477:Perfusion; D010646:Phentolamine / Q000494:pharmacology; D011942:Receptors, Adrenergic, alpha / Q000502:physiology; D013961:Thyroid Gland / Q000378:metabolism*; D013972:Thyrotropin / Q000037:antagonists & inhibitors*; D013974:Thyroxine / Q000378:metabolism*
D011942:Receptors, Adrenergic, alpha; D013972:Thyrotropin; D000242:Cyclic AMP; D007545:Isoproterenol; D013974:Thyroxine; D009638:Norepinephrine; D004837:Epinephrine; D010646:Phentolamine