title: Further observations on the autoregulation of the prolactin receptor in rat ventral prostate explants.
abstract: In confirmation and extension of an earlier preliminary communication, ovine prolactin was found to elevate prolactin binding by approximately 100% in rat ventral prostate explants incubated for 20 h in vitro. A stimulation was observed with low doses of ovine hormone (150 micrograms/l) which, from available data on the relative biological potencies, could be considered equivalent to the upper limit of the physiological range of endogenous rat prolactin. The response was associated with a lag period of 3-6 h. The effect could be obtained with other lactogenic hormones, including human and rat prolactin and human growth hormone, but not with non-lactogenic hormones such as insulin, hCG, corticosterone, testosterone or oestradiol. The prostaglandin synthesis inhibitor, indomethacin, and the Ca2+-antagonist, verapamil, could not counteract the increase in prolactin binding induced by prolactin treatment, nor could dibutyryl cyclic AMP alone mimic the response. These data suggest that prostaglandins, Ca2+ or cAMP do not mediate the alteration in receptor binding. Furthermore, inhibition of lysosome activity by chloroquine could not alone increase the prolactin binding in the control tissues, suggesting that up-regulation does not simply reflect a protective action of prolactin on receptor degradation.
mesh_terms: D000818:Animals; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D003345:Corticosterone / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology; D013006:Growth Hormone / Q000494:pharmacology; D006706:Homeostasis / Q000187:drug effects; D007328:Insulin / Q000494:pharmacology; D008297:Male; D011388:Prolactin / Q000502:physiology*; D011467:Prostate / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011981:Receptors, Prolactin / Q000187:drug effects / Q000378:metabolism*; D013739:Testosterone / Q000494:pharmacology
chemical_list: D006063:Chorionic Gonadotropin; D007328:Insulin; D011981:Receptors, Prolactin; D013739:Testosterone; D004958:Estradiol; D011388:Prolactin; D013006:Growth Hormone; D003345:Corticosterone