title: Dopaminergic control of the rat thyrotroph.
abstract: The established technique of dynamic perfusion of dispersed rat anterior pituitary cells was used to investigate the role of dopamine in the release of thyroid-stimulating hormone (TSH). The basal release of TSH was 124 +/- 22 ng/ml (mean +/- SEM) and this remained unchanged in the presence of dopamine (5 X 10(-6) M), while basal prolactin release was suppressed to 50% of control values. Perfusion with thyrotrophin-releasing hormone (TRH) in doses between 1.4 X 10(-10) and 22.4 X 10(-10) M produced a consistent and reproducible dose-response curve for TSH (n = 14) which was not significantly altered by the presence of dopamine (n = 5). Perfusion with bromocriptine (10(-6) M), a dopamine agonist, did not alter the basal or stimulated TSH release. No stimulation of TSH release was observed when the cells were challenged with 2-min pulses of domperidone, a dopamine antagonist (2 X 10(-9) to 2 X 10(-5) M). The inclusion of somatostatin-14 (3 X 10(-9) M) in the perfusate inhibited TRH-stimulated TSH release. Our results suggest that, in the rat, dopaminergic inhibition of TSH release does not occur at the level of the pituitary.
mesh_terms: D000818:Animals; D001971:Bromocriptine / Q000494:pharmacology; D004294:Domperidone / Q000494:pharmacology; D004298:Dopamine / Q000494:pharmacology / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D010477:Perfusion; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000378:metabolism*; D051381:Rats / Q000502:physiology*; D011919:Rats, Inbred Strains; D013004:Somatostatin / Q000494:pharmacology; D013972:Thyrotropin / Q000378:metabolism; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology
chemical_list: D001971:Bromocriptine; D013004:Somatostatin; D004294:Domperidone; D013973:Thyrotropin-Releasing Hormone; D013972:Thyrotropin; D004298:Dopamine