title: The effect of somatostatin on the release of thyrotropin and its subunits from bovine anterior pituitary cells in vitro.
abstract: The effects of somatostatin (SRIF) on the production and release of TSH and its subunits have been investigated in bovine anterior pituitary monolayer cultures. SRIF caused a dose-dependent inhibition of TSH and subunit release by TRH, with a half-maximal effective dose of 3 X 10(-8) M. This effect was time dependent and was greater for TSH than for its subunits. However, the basal release and total production of TSH and its subunits over a 24-h period were not affected by SRIF. The effect of SRIF was additive to that of thyroid hormones in suppressing the release of TSH and its subunits by TRH. A combination of SRIF and thyroid hormone completely suppressed the release of TSH and its subunits by TRH. In contrast, thyroid hormones caused a dose-dependent inhibition of the total production, as well as the release, of TSH and its subunits induced by TRH. Furthermore, thyroid hormones produced a dose-dependent increase (r = 0.81; P less than 0.001) in the effectiveness of a single dose of SRIF in suppressing TSH release by TRH. Analysis of these data revealed that thyroid hormones interacted synergistically with the SRIF effect to suppress TRH-mediated TSH and subunit release.
mesh_terms: D000818:Animals; D002417:Cattle; D007700:Kinetics; D046911:Macromolecular Substances; D008297:Male; D009924:Organ Culture Techniques; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism*; D011863:Radioimmunoassay; D013004:Somatostatin / Q000494:pharmacology*; D013972:Thyrotropin / Q000378:metabolism*; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology; D013974:Thyroxine / Q000494:pharmacology; D014284:Triiodothyronine / Q000494:pharmacology
chemical_list: D046911:Macromolecular Substances; D014284:Triiodothyronine; D013004:Somatostatin; D013973:Thyrotropin-Releasing Hormone; D013972:Thyrotropin; D013974:Thyroxine