The effect of rearing under a long or short photoperiod on testis growth, plasma testosterone and prolactin concentrations, and the development of sexual behaviour in rams.
The effect of rearing under a long or short photoperiod on testis growth, plasma testosterone and prolactin concentrations, and the development of sexual behaviour in rams.
复制标题
长光周期或短光周期饲养对公羊睾丸生长、血浆睾酮和催乳素浓度以及性行为发育的影响。
DOI：
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发表时间：
1980
期刊：
影响因子：
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通讯作者：
N. B. Haynes
中科院分区：
文献类型：
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作者：
C. Howles;G. Webster;N. B. Haynes
从4 ~ 20月龄，每组6只公羊在短日（8 h光照，16 h黑暗，S组）和长日（16 h光照，8 h黑暗，L组）的恒定光周期条件下饲养。另外5只公羊在自然发生的光周期代表下饲养（N组）。每周监测睾丸大小、血浆睾酮和催乳素浓度，并定期进行性行为测试。在治疗期间，S组和L组在睾丸生长和血浆睾酮方面没有差异。两组都有一个睾丸生长的阶段，睾丸激素增加，然后下降，两组的时间模式是相同的。性行为在L组的发展速度比S组慢，这表明光周期可以影响性行为的发展，而与外周血浆睾酮浓度无关。血浆催乳素水平在L组呈周期性变化，总体上显著高于S组。这与L组中催乳素浓度与性行为呈负相关的趋势表明，催乳素可能参与了光周期对性行为的影响。在恒定光周期下，幼龄动物睾丸生长周期和激素浓度周期的存在初步表明，这些周期是内源性的。然而，恒定的光周期确实对动物产生了影响，因为S组和L组发生的周期与N组的周期相差约4个月。
Two groups of 6 rams were maintained under constant photoperiodic conditions consisting of short days (8 h light: 16 h dark; Group S) and long days (16 h light; 8 h dark; Group L) from 4 to 20 months of age. Five other rams were reared under a photoperiod representative of that occurring naturally (Group N). Testis size, plasma testosterone and prolactin concentrations were monitored weekly and sexual behaviour tests were carried out at regular intervals. Over the treatment period Groups S and L did not differ in terms of testis growth or plasma testosterone. Both groups had a phase of testis growth and increased testosterone followed by a decline and the temporal patterns for the two groups were equivalent. Sexual behaviour was slower to develop in Group L than in Group S, indicating that photoperiod can affect the development of sexual behaviour irrespective of peripheral plasma testosterone concentrations. Plasma prolactin levels showed a cyclic variation in Group L and were significantly higher overall than in Group S rams. This, together with a trend towards negative correlations between prolactin concentrations and sexual behaviour in Group L, indicates that prolactin may be involved in the effect of photoperiod on sexual behaviour. The presence of a cycle of testicular growth and of hormone concentrations in young animals under constant photoperiod tentatively suggests that these cycles are endogenous. The constant photoperiod did, however, affect the animals because the cycles which occurred in Groups S and L were out of phase with those of Group N by about 4 months.