INDUCTION OF PRECOCIOUS PUBERTY IN FEMALE RATS BY PROLACTIN

Injections of prolactin significantly advanced the onset of puberty in immature rats by about 6 days when given at 20 days of age and by 2 days when given ai 25 days of age. Injections of other anterior pituitary hormones (FSH, I.H, TSH, GH) in amounts specified to be present in the NIH prolactin preparations did not advance the onset of puberty. Prolactin injections into hypophyseccomized rats were also ineffective. Implants of prolactin into the median eminence hastened the onset of puberty by an average of 6.6 days, whereas implants of doses of other hormones stated to be present in the prolactin preparation had no effect on the onset of puberty. The advancement of puberty by prolactin administration is believed to be mediated through the hypothalamus and to result in decreased prolactin and increased pituitary FSH secretion. © 1969 S. Karger AG, Basel.