In vivo autoregulation of rat adenohypophyseal thyrotropin-releasing hormone receptor.
The possible mechanism of attenuation of thyrotropin response to exogenous thyrotropin-releasing hormone in vivo after repeated administrations of the releasing hormone has been studied. To this end, the effect of prolonged hormone treatment on the binding of hormone to its receptor in the anterior pituitary gland has been evaluated. The data show that prolonged hormonal treatment resulted in a reduction in the number (B max) but no the binding affinity (KD) of the receptor. The effect was reversible and depended on the duration of treatment. This phenomenon of down regulation or the decrease in the receptor number was found not to be due to either the metabolism of releasing hormone or its ability to activate pituitary-thyroid-axis.
D000818:Animals; D006706:Homeostasis; D008297:Male; D010903:Pituitary Gland, Anterior / Q000032:analysis* / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000032:analysis*; D018025:Receptors, Thyrotropin-Releasing Hormone; D013972:Thyrotropin / Q000494:pharmacology; D013973:Thyrotropin-Releasing Hormone / Q000378:metabolism / Q000494:pharmacology; D013974:Thyroxine / Q000494:pharmacology
D011956:Receptors, Cell Surface; D018025:Receptors, Thyrotropin-Releasing Hormone; D013973:Thyrotropin-Releasing Hormone; D013972:Thyrotropin; D013974:Thyroxine