title: Biphasic inhibitory and stimulatory effects of thyrotropin on the mitotic activity of thyroid explants cultured in vitro.
abstract: An influence of thyrotropin (TSH), dibutyryl cyclic AMP (dbcAMP), triiodothyronine (T3) and thyroxine (T4) on the mitotic incidence in the organ-cultured rat thyroid was studied. The study has revealed biphasic inhibitory and stimulatory effects of TSH on the thyroid mitotic activity. The inhibitory effect occurred 14 h after an exposure of the thyroid explants to TSH and was enhanced by T3. A similar inhibitory effect was observed after an exposure of the explants to dbcAMP. 24 h after the exposure of the thyroid explants to TSH a stimulatory effect on the mitotic incidence was observed. The latter effect was not reproduced by dbcAMP.
mesh_terms: D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D008297:Male; D008938:Mitosis / Q000187:drug effects*; D009924:Organ Culture Techniques; D051381:Rats; D013961:Thyroid Gland / Q000187:drug effects / Q000502:physiology*; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*; D013974:Thyroxine / Q000494:pharmacology; D014284:Triiodothyronine / Q000494:pharmacology
chemical_list: D014284:Triiodothyronine; D013973:Thyrotropin-Releasing Hormone; D003994:Bucladesine; D013974:Thyroxine