title: In vivo release of prolactin in Rana ridibunda following an intravenous injection of thyrotropin-releasing hormone.
abstract: All experiments were performed on female Rana ridibunda during the months of April and May. Injections were made into the canulated vena abdominalis and blood samples were taken up to 8 hr thereafter and checked for prolactin concentration using a heterologous frog radioimmunoassay. An injection of 10 micrograms TRH (thyrotropin releasing hormone; pGlu-His-Pro NH2) will elevate control serum levels of 28.54 +/- 5.40 ng/ml prolactin to 59.56 +/- 8.78 ng/ml (n = 6) and this within half an hour. A smaller increase was present with 1 microgram of TRH and none with 0.1 or 0.01 microgram. Prolactin remains elevated up to 2 hr after the injection but reaches control values again after 4 hr. Two days after removal of the pars distalis serum levels have declined to 14.48 +/- 1.67 ng/ml (n = 15) and no influence of TRH injections, tested at several doses, on this is seen. previous thyroxine (T4) and tri-iodothyronine (T3) assays using the same blood have revealed that 1 and 10 micrograms TRH also increases T4 in a dose-related way after 1 hr, with a maximal increase at 2 hr, and T3 after 4 hr. It is concluded that TRH is able to induce the release of both prolactin and TSH from the hypophysis in the frog R. ridibunda as it does in mammals.
mesh_terms: D000818:Animals; D005260:Female; D007700:Kinetics; D010903:Pituitary Gland, Anterior / Q000502:physiology; D011388:Prolactin / Q000097:blood*; D011895:Rana ridibunda / Q000097:blood*; D011898:Ranidae / Q000097:blood*; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood
chemical_list: D014284:Triiodothyronine; D013973:Thyrotropin-Releasing Hormone; D011388:Prolactin; D013974:Thyroxine