In vitro effect of TRH on adenylate cyclase and cAMP in rat anterior pituitary and on TSH and PRL release into incubation medium.
Rat anterior pituitaries were incubated for 20 min with 1, 5 or 20 nmol TRH ml-1 and cAMP was measured in the homogenate of pituitary tissue after incubation, while TSH and PRL release into the medium was estimated with the aid of specific radioimmunoassay. In a similar experiment the activity of adenylate cyclase in pituitary homogenates was measured after the incubation with 0.5, 1.0 or 5.0 nmol TRH ml-1. Significant increase of TSH and PRL in the medium was found after 5 and 20 nmol TRH ml-1, while cAMP was significantly increased after 20 nmol TRH ml-1 only. The activity of adenylate cyclase was significantly increased after all doses of TRH used. In general, these findings are consistent with current views on the effect of hypothalamic hormones via adenylate cyclase - cAMP system and show that the responsiveness and sensitivity of an in vitro system using whole pituitaries appears to be less that of in vivo system.
D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D008297:Male; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D011388:Prolactin / Q000378:metabolism*; D051381:Rats; D013972:Thyrotropin / Q000378:metabolism*; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*
D013973:Thyrotropin-Releasing Hormone; D011388:Prolactin; D013972:Thyrotropin; D000242:Cyclic AMP; D000262:Adenylyl Cyclases