SEX DIFFERENCE IN THE INDUCTION OF LACTOGENIC RECEPTORS IN RAT LIVERS

Publisher Website
Google Scholar
Abstract
The relationship between serum levels of growth hormone (GH), prolactin (PRL), luteinizing hormone (LH), follicle-stimulating hormone (FSH), corticosterone, estrogen, (estradiol-17.beta.) and testosterone and the hepatic binding sites specific to [125I] human (h)PRL were investigated in normal rats, in rats bearing the GH- and PRL-secreting tumor (GH3), and in rats 14 days after tumor removal. The presence of GH3 tumor elevated serum levels of r[rat]GH and rPRL and concomitantly increased the hepatic binding of [125I]hPRL; the male rats had a greater increase than the female rats. The increased binding was due to an increase in the specific membrane binding sites, whereas the affinity constant (Ka) was not changed. In both male and female rats, there was a significant positive correlation between serum rGH levels (P < 0.001) and serum rPRL (P < 0.02) and there was specific binding of [125I]hPRL in female rats only (P < 0.02). Im male rats, there was a significant negative correlation between serum testosterone levels and specific binding of [125I]hPRL (P < 0.05). rGH and rPRL may regulate the hepatic hPRL receptors in female rats, and testosterone predominantly inhibits the induction of the hepatic lactogenic receptors in male rats.