Changes in pituitary prolactin legels in rats from weaning to adulthood.

Abstract

Changes in anterior pituitary prolactin content and concentration were investigated in female rats from weaning to adulthood. Prolactin was measured by the intradermal pigeon crop sac method. Prolactin content was uniformly low at 21, 26, 31 days of age and on the day of vaginal opening (about 37.5 days). Pituitary prolactin content markedly increased shortly after the onset of puberty, and remained high during subsequent estrous cycles. Daily injections of 10 μg of estradiol benzoate to prepubertal rats for 5 days beginning at 25 days of age markedly increased pituitary prolactin content and concentration over that of untreated controls of the same age. These results suggest that pituitary prolactin levels are very low before and at the beginning of puberty, but increase significantly after puberty is established. These increases are believed to be due mainly to increased estrogen secretion by the ovaries. (Endocrinology82: 555, 1968)