Homologous up-regulation of the prolactin receptor in rat prostatic explants.
Exposure of explants of rat ventral prostates and a rat Leydig cell tumour to ovine prolactin for 20 h caused alterations of the subsequent membrane binding of 125I-human prolactin to an extent and in a direction dependent on the dose of hormone used. Low prolactin concentrations (1-10 micrograms/2 ml) were associated with an increase in binding (up-regulation) which was 75% in the case of the prostatic tissue and 500% in the case of the tumour tissue above control levels. Higher concentrations caused a dose-dependent decrease in binding to below control levels (down-regulation), alterations which could not be explained by receptor occupancy. Time studies with an up-regulatory dose of hormone (3 micrograms/2 ml) indicated that the effects of prolactin on its receptor did not begin to become manifest until after 6-12 h of culture. The results suggest that homologous up-regulation of prolactin binding may be a general feature of prolactin target organs and that explant cultures of prostatic tissue may provide a convenient model for exploring its mechanisms.
D000818:Animals; D046508:Culture Techniques; D007700:Kinetics; D007984:Leydig Cell Tumor / Q000378:metabolism*; D008297:Male; D011388:Prolactin / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D011467:Prostate / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism*; D011981:Receptors, Prolactin
D011956:Receptors, Cell Surface; D011981:Receptors, Prolactin; D011388:Prolactin