FSH Induction of Sensitivity to LH:One Cause of Sexual Maturation in the Male Rat1

Publisher Website
Google Scholar
Abstract
The sensitivity of the testicular response to exogenous LH and FSH has been evaluated in sexually immature and mature animals. Male rats were hypophysectomized at 21 days of age (weaning) and 87 days of age (sexually mature). Five days later, NIH—LH—B7 was administered daily for 5 days in doses ranging from 0.04-400 μ/100 g bw/day. Sexually immature males showed no response to any dose of LH, while sexually mature animals responded to 0.66 μg and showed a maximal response to 20 μg. However, the sexually immature 5-day hypophysectomized animal responded to NIH—FSH—S4; 8 μg/100 g bw/day, given over 5 days, significantly increased testicular wt, and 300 μg produced a maximal response. FSH alone failed to stimulate prostate wt. The minimal effective dose of testosterone required to increase prostate wt was identical in immature and mature animals. Thus, failure of prostate wt to respond to LH stimulation was not due to interference with testosterone action. Pretreatment of sexually immature, 5-day hypophysectomized animals with FSH (60 μg/ day/100 g bw) for varying times followed by FSH plus LH (20 μg/day/100 g bw) produced a significant increase in prostate wt. LH given alone produced no effect. Moreover this increment in prostate wt became progressively greater with time. The ratio of prostate wt of FSH—LH animals/ prostate weight saline control animals after varying periods of treatment was as follows: 10 days, 7.2 μg/5.3 μg; 25 days, 8.5/5.2; 30 days, 13.5/ 4.7. Thus, a time—response relationship existed. We postulate that in the male rat, FSH induces sensitivity to LH. Thus, sexual maturation may occur without the requirement for an increase in LH or FSH concentrations or an alteration in feedback sensitivity. During sexual maturation, gonadal responsiveness to LH changes with continued testicular stimulation by FSH.(Endocrinology92: 160,1973)

This publication has 0 references indexed in Scilit: