Hötzel M J, Caraty A, Martin G B
Faculty of Agriculture (Animal Science), University of Western Australia, Nedlands, Australia.
J Reprod Fertil. 1997 Jul;110(2):307-13. doi: 10.1530/jrf.0.1100307.
Nutrition-induced changes in testicular size in Merino rams appear to involve both GnRH-dependent and -independent pathways. This hypothesis was tested by feeding mature Merino rams that had been actively immunized against BSA or GnRH conjugated to BSA a diet that maintained initial body weight or the same diet supplemented daily with 1.5 kg of lupin grain. Blood was sampled every 20 min for 24 h on days-1, 19 and 70 relative to the change in diet. The plasma was used to assess the effects of treatments on changes in LH, FSH and testosterone concentrations. In the group immunized against BSA, FSH increased in lupin-supplemented rams compared with maintenance-fed rams, while LH and testosterone were not affected by diet. In comparison, the concentrations of LH, FSH and testosterone were significantly lower in the group immunized against GnRH than in rams immunized against BSA, but none of these endocrine variables was affected by nutrition. With both immunization treatments, the testes were significantly larger in lupin-supplemented than in maintenance-fed rams. In the group immunized against BSA, this difference was caused by testicular growth in lupin-supplemented rams, whereas in the group immunized against GnRH, lupin supplementation effectively maintained testicular mass, rather than allowed the regression observed in maintenance-fed rams. In conclusion, differences in testicular growth that were induced by dietary treatments in rams immunized against GnRH were not associated with changes in gonadotrophin or testosterone secretion. This supports the hypothesis that part of the effect of nutrition on testicular growth is independent of changes in GnRH secretion. The differences in testicular size observed in control rams were of similar magnitude to those observed in treated rams, but associated with large differences in plasma FSH concentrations, suggesting that this hormone plays an important role in this effect.
营养诱导美利奴公羊睾丸大小的变化似乎涉及促性腺激素释放激素（GnRH）依赖性和非依赖性途径。通过给主动免疫牛血清白蛋白（BSA）或与BSA偶联的GnRH的成年美利奴公羊喂食维持初始体重的日粮或每天添加1.5千克羽扇豆谷物的相同日粮来验证这一假设。在相对于日粮变化的第-1天、第19天和第70天，每20分钟采集一次血样，共采集24小时。血浆用于评估处理对促黄体生成素（LH）、促卵泡生成素（FSH）和睾酮浓度变化的影响。在免疫BSA的组中，与维持喂养的公羊相比，添加羽扇豆的公羊FSH增加，而LH和睾酮不受日粮影响。相比之下，免疫GnRH的组中LH、FSH和睾酮的浓度显著低于免疫BSA的公羊，但这些内分泌变量均不受营养影响。两种免疫处理下，添加羽扇豆的公羊睾丸明显大于维持喂养的公羊。在免疫BSA的组中，这种差异是由添加羽扇豆的公羊睾丸生长引起的，而在免疫GnRH的组中，添加羽扇豆有效地维持了睾丸质量，而不是像维持喂养的公羊那样出现睾丸退化。总之，在免疫GnRH的公羊中，日粮处理诱导的睾丸生长差异与促性腺激素或睾酮分泌的变化无关。这支持了营养对睾丸生长的部分影响独立于GnRH分泌变化这一假设。在对照公羊中观察到的睾丸大小差异与在处理公羊中观察到的差异幅度相似，但与血浆FSH浓度的巨大差异相关，表明这种激素在这一效应中起重要作用。
