Jackson G L, Kuehl D, Rhim T J
Department of Veterinary Biosciences, University of Illinois, Urbana 61801.
Biol Reprod. 1991 Jul;45(1):188-94. doi: 10.1095/biolreprod45.1.188.
The objective was to determine the effect of chronic testosterone (T) treatment on GnRH and LH secretion in wethers. Rams were either castrated only or castrated and immediately treated with Silastic implants containing T. Several weeks later, a device for collecting hypophyseal-portal blood was surgically implanted. Six to seven days later, blood samples were collected simultaneously and continuously from the portal vessels and jugular vein of pairs of conscious animals. Samples were divided at 10-min intervals for 6-12 h. One hour before the end of collection, all animals received i.v. injections of 250 ng of GnRH. In samples collected simultaneously from 6 pairs of animals, T reduced the frequency of both GnRH pulses (1.8 +/- 0.2 vs. 0.9 +/- 0.3/h, p less than 0.03) and LH pulses (1.6 +/- 0.1 vs. 0.8 +/- 0.3/h, p less than 0.03). T did not alter amplitude of either GnRH or LH pulses. Testosterone reduced mean GnRH (9.7 +/- 0.6 vs. 7.9 +/- 0.5 pg/ml, p less than 0.05), whereas mean LH was not significantly reduced (9.6 +/- 1.4 vs. 6.1 +/- 1.8 ng/ml, p = 0.16). These results support the hypothesis that T reduces GnRH pulse frequency.
目的是确定慢性睾酮（T）治疗对去势公羊促性腺激素释放激素（GnRH）和促黄体生成素（LH）分泌的影响。公羊要么仅进行去势，要么去势后立即用含T的硅橡胶植入物进行治疗。几周后，通过手术植入一种用于采集垂体门脉血的装置。六到七天后，从成对的清醒动物的门脉血管和颈静脉同时连续采集血样。样本每隔10分钟进行一次分割，持续6 - 12小时。在采集结束前一小时，所有动物静脉注射250 ng的GnRH。在从6对动物同时采集的样本中，T降低了GnRH脉冲频率（1.8±0.2对0.9±0.3次/小时，p<0.03）和LH脉冲频率（1.6±0.1对0.8±0.3次/小时，p<0.03）。T未改变GnRH或LH脉冲的幅度。睾酮降低了平均GnRH水平（9.7±0.6对7.9±0.5 pg/ml，p<0.05），而平均LH水平未显著降低（9.6±1.4对6.1±1.8 ng/ml，p = 0.16）。这些结果支持T降低GnRH脉冲频率这一假说。
