Prolactin receptor in rat liver: Sex difference in estrogenic stimulation and imprinting of the responsiveness to estrogen by neonatal androgen in male rats

Abstract

Rat hepatic prolactin receptor is regulated by sex steroids. A high level of the receptor was found in female rats but the level was nearly undetectable in males. Gonadectomy reduced the receptor level in females but increased the level in males. Administration of estradiol benzoate (0.05 μmoles/kg on alternate days subcutaneously for 9 days) to adult gonadectomized females increased the receptor level by 473% whereas the same treatment in adult gonadectomized males produced a more modest 276% increase. This sexually dimorphic pattern in the responsiveness to estrogen stimulation in adult rats appeared to be determined neonatally. Neonatal gonadectomy of male rats changed the hepatic response system to a more female pattern in adulthood. Replacement of testosterone (1.45 μmoles at days 1 and 3 after birth) to these neonatally gonadectomized male rats restored the male pattern. Diethylstilbestrol replacement (1.45μmoles at days 1 and 3 after birth) to the neonatally gonadectomized male rats showed the same effect as neonatally administered testosterone. Scatchard analysis revealed that the observed changes in binding are related to changes in binding capacity but not affinity. Desaturation by 4 M MgCl2 indicated that the amount of endogenously bound hormone was negligible in our membrane preparations. © 1985