Use of a pulsed infusion of luteinizing hormone releasing hormone to mimic seasonally induced endocrine changes in the ram.
Use of a pulsed infusion of luteinizing hormone releasing hormone to mimic seasonally induced endocrine changes in the ram.
复制标题
使用黄体生成素释放激素的脉冲输注来模拟公羊季节性引起的内分泌变化。
作者：
G. Lincoln
成年Soay公羊在春季非交配季节被饲养在自然光照下，此时促性腺激素分泌较低。4只动物接受小剂量(100 ng或500 ng)促黄体生成素释放激素(LH-RH)机械装置颈静脉注射，每隔2小时给60只S，持续33~57天；另2只公羊作为对照。长期使用促黄体生成素-促性腺激素会导致睾丸生长和性皮肤潮红的发展；当治疗停止时，这些影响就会消失。血浆中促黄体生成素、卵泡刺激素和睾酮的浓度在开始时较低，每次短期输注促黄体生成素-促性腺激素可使促黄体生成素和睾酮水平短暂升高，而对卵泡刺激素浓度的影响不大。长期给予500 ng脉冲的促黄体生成素-促性腺激素治疗后，所有三种激素的血浆浓度都永久性地升高。对单次注射黄体生成素-RH的反应也有所改变，黄体生成素峰值降低，但延长，而促卵泡刺激素和睾酮反应均增强。停止脉冲输液后，血清中的黄体生成素和睾酮浓度迅速下降，而促卵泡刺激素水平的下降持续时间较长。这些由脉冲输液引起的内分泌变化与交配季节前公羊睾丸重新发育期间自然发生的内分泌变化相当。
Adult Soay rams were housed indoors under natural lighting during the spring non-mating season when gonadotrophin secretion was low. Four animals received small doses (100 ng or 500 ng) of synthetic LH releasing hormone (LH-RH) infused into the jugular vein by a mechanical device for 60 s every 2 h for 33-57 days: two other rams acted as controls. The prolonged treatment with LH-RH resulted in growth of the testes and the development of the sexual skin flush; these effects were lost when treatment stopped. The plasma concentrations of LH, FSH and testosterone were low at the beginning; each short infusion of LH-RH resulted in a transitory increase in the level of LH and testosterone while the concentration of FSH was only marginally affected. After prolonged treatment with 500 ng pulses of LH-RH the plasma concentrations of all three hormones were permanently raised. The response to the individual injections of LH-RH was also modified, the peak in LH being reduced in amplitude but more prolonged while the FSH and testosterone responses were both enhanced. When the pulsed infusion was stopped the concentration of LH and testosterone declined rapidly while the decline in FSH levels took many days. These endocrine changes induced by the pulsed infusion are comparable to those that occur naturally in the ram during testicular redevelopment before the mating season.