Presence of high affinity dopamine receptors in estrone-induced, prolactin-secreting rat pituitary adenomas: a model for human prolactinomas.
Adenomatous cells obtained from a pituitary tumor induced in Fisher 344/Lis rats by the subcutaneous implantation of estrone (E1) were found to secrete large amounts of prolactin (PRL). The secretion of PRL was stimulated by thyrotropin-releasing hormone (TRH) and low concentrations of dopamine (DA), while micromolar concentrations of DA were inhibitory. High affinity binding sites for 3H-spiroperidol (3H-SPIR) were found to be present on the cells and to conform to the criteria of dopaminergic receptors. An adenylate cyclase (AC) present in the cells could be activated by a guanyl nucleotide and was inhibited by DA in the presence of guanosine 5'-triphosphate (GTP). Fractionation of the adenomatous cells by Percoll gradients identified two groups of cells capable of secreting PRL and bearing 3H-SPIR binding sites. These data indicate that this rat pituitary adenoma may be a model for human prolactinomas that might be utilized for the study of the mechanism of action of dopaminergic drugs.
D000236:Adenoma / Q000139:chemically induced / Q000378:metabolism*; D000818:Animals; D001971:Bromocriptine / Q000494:pharmacology; D004195:Disease Models, Animal; D004298:Dopamine / Q000494:pharmacology; D004970:Estrone; D005260:Female; D006160:Guanosine Triphosphate / Q000494:pharmacology; D010911:Pituitary Neoplasms / Q000139:chemically induced / Q000378:metabolism*; D011388:Prolactin / Q000378:metabolism*; D051381:Rats; D011916:Rats, Inbred F344; D011954:Receptors, Dopamine / Q000378:metabolism*; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology
D011954:Receptors, Dopamine; D004970:Estrone; D001971:Bromocriptine; D013973:Thyrotropin-Releasing Hormone; D006160:Guanosine Triphosphate; D011388:Prolactin; D004298:Dopamine