The Influence of Estrogen Administration on Plasma Prolactin Levels in the Neonatally Androgenized (NA) Female Rat 1

Abstract

Diurnal plasma prolactin levels were examined in intact neonatally androgenized (NA) female rats and NA rats ovariectomized (OVX) as adults and given estrogen. The administration of 0.5 mg of polyestradiol phosphate (PEP) to NA-OVX animals resulted in a diurnal plasma prolactin pattern similar to that of intact NA animals. When compared with normal OVX PEP-treated animals the plasma PRL levels of NA animals were higher at 0900, 1100, and 1300 hr and lower at 1500, 1700, 1900, and 2100 hr. In intact NA and NA-OVX estrogen-treated animals plasma prolactin values were significantly higher in the afternoon when compared with morning values. Plasma estradiol was twice as high in intact NA animals than in NA-OVX animals while PEP-injected animals had a value 14 times higher than that of intact NA rats. Despite the very high estradiol value the plasma PRL pattern of NA-OVX + PEP animals was comparable to intact NA animals. The ovaries were smaller and the oviducts larger in NA animals when compared to controls. Uterine growth to exogenous estrogen was significantly reduced in NA animals when compared to normal animals while adrenal and anterior pituitary growth and thymus involution were similar.