| Autor: |
Kitahara, Atoshi, Winters, Stephen J., Oshima, Hiroyuki, Troen, Philip |
| Zdroj: |
Biology of Reproduction; January 1991, Vol. 44 Issue: 1 p121-126, 6p |
| Abstrakt: |
The effectiveness of androgens in suppressing gonadotropin secretion declines with time following orchidectomy; however, the mechanism for this acquired resistance to androgen action is unknown. The role of the pituitary was studied by use of perifused rat pituitary cells and cells in monolayer culture. Pituitary cells from 7-wk-old intact male rats and rats that had been castrated 2 wk previously were treated with 10 nM testosterone (T) for 24 h; cells were then packed into perifusion chambers and stimulated with 2.5 nM GnRH for 2 min every hour for 8 h during which time T treatment was continued. T suppressed GnRH-stimulated LH secretion and LH pulse amplitude equally in both groups to approximately 60% of control values. Interpulse LH secretion was unchanged by T in either group. GnRH-stimulated FSH release was suppressed more (p< 0.05) by T with cells from castrated rats than with cells from intact rats (76 ± 4% vs. 90 ± 2% of control; mean ± SEM). By contrast, the action of T to increase interpulse basal FSH secretion was less (p< 0.05) with cells from castrated rats (115 ± 10% of control) than with cells from intact rats (146 ± 6% of control). T treatment for 72 h also increased basal FSH secretion by pituitary cells in monolayer culture to a lesser extent with cells from castrated rats than with cells from intact rats (151 ± 14% vs. 191 ± 16% of control, p< 0.05).These data indicate that T suppresses pulsatile LH and FSH secretion partly througıs an action on the pituitary in both castrated and intact rats. The reduced T effect on UI observed in vivo appears to be more consistent with a change in the control of GnRH secretion with castration rather than with an effect directly on the pituitary. There is a different mechanism for the stimulatory effect of T on interpulse and basal FSH release, and this action of T is reduced after orchidectomy |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
|
