Adam C L, Findlay P A
Molecular Neuroendocrinology Unit, Rowett Research Institute, Bucksburn, Aberdeen, UK.
J Reprod Fertil. 1997 Sep;111(1):121-5. doi: 10.1530/jrf.0.1110121.
Nutritional effects on puberty were studied in Soay rams. Testicular growth is initiated at birth in April and testes reach maximum size in October. Groups of eight lambs were fed for 18 weeks, starting in August, a ration that restricted growth (Group R), the same diet ad libitum (Group F), or a restricted diet for 8 weeks followed by ad libitum feeding (Group R/F). Seasonal increases of plasma FSH, testis size, sexual skin flush and plasma testosterone occurred with similar timing but reduced magnitude in Group R compared with Group F lambs. Testis size and sexual skin flush peaked in all groups at 11 weeks (30 October); the testes of Group F animals were larger before the peak, but similar in size thereafter, compared with testes from Group R/F, and larger throughout the experimental period than testes from Group R. Plasma testosterone was higher in Group F than in Group R lambs from 7 to 17 weeks, but in Group R/F was similar to Group R before 10 weeks (23 October) and similar to Group F thereafter. Testis size, plasma testosterone, plasma insulin-like growth factor I (IGF-I) and liveweight were positively correlated. Ad libitum feeding in August-September (Group F) stimulated increased plasma FSH and LH above values for Group R, but ad libitum feeding initiated in October did not affect gonadotrophin concentrations (Group R/F). Therefore, the effects of improved nutrition on the hypothalamo-pituitary axis, which may have been mediated by circulating IGF-I, were season- or age-dependent, and those on the testes included direct stimulation, independent of changes in gonadotrophin concentrations. Nutrition modified the intensity, but not the timing, of peak pubertal reproductive activation.
在索艾羊公羊中研究了营养对青春期的影响。睾丸生长于4月出生时开始，10月时睾丸达到最大尺寸。从8月开始，将8只羔羊分为一组，分别给予限制生长的日粮（R组）、随意采食相同日粮（F组），或先限制采食8周然后改为随意采食（R/F组），持续喂养18周。与F组羔羊相比，R组血浆促卵泡激素（FSH）、睾丸大小、性皮肤潮红和血浆睾酮的季节性增加出现时间相似，但幅度减小。所有组的睾丸大小和性皮肤潮红在11周（10月30日）时达到峰值；F组动物的睾丸在峰值前较大，但此后与R/F组的睾丸大小相似，且在整个实验期内都比R组的睾丸大。在7至17周期间，F组的血浆睾酮高于R组羔羊，但R/F组在10周（10月23日）前与R组相似，此后与F组相似。睾丸大小、血浆睾酮、血浆胰岛素样生长因子I（IGF-I）和体重呈正相关。8月至9月随意采食（F组）刺激血浆FSH和LH升高至高于R组的值，但10月开始的随意采食不影响促性腺激素浓度（R/F组）。因此，营养改善对下丘脑-垂体轴的影响可能由循环中的IGF-I介导，具有季节或年龄依赖性，对睾丸的影响包括直接刺激，独立于促性腺激素浓度的变化。营养改变了青春期生殖激活峰值的强度，但未改变其时间。
