Effect of prolonged exposure to nonstimulatory photoperiods on the activity of the neuroendocrine-testicular axis of golden hamsters.
Effect of prolonged exposure to nonstimulatory photoperiods on the activity of the neuroendocrine-testicular axis of golden hamsters.
复制标题
长时间暴露于非刺激性光周期对金仓鼠神经内分泌睾丸轴活动的影响。
DOI：
10.1095/biolreprod13.4.475
复制
发表时间：
1975
影响因子：
3.6
通讯作者：
Michael Menaker
中科院分区：
文献类型：
--
作者：
Fred W. Turek;Jeffrey A. Elliott;Janet D. Alvis;Michael Menaker
将雄性金黄地鼠暴露于无刺激性短日照25周，每两周测定一次对性腺重量和血清促性腺激素水平的影响。在11周内，动物从光刺激（LD 14：10）转换到非刺激（LD 6：18）光周期后，血清LH和FSH滴度以及睾丸重量显著下降（分别为4倍、5倍和13倍）。持续暴露于LD 6：18导致血清促性腺激素水平逐渐升高，随后在25周时睾丸完全复发（再生）。睾丸本身似乎不参与血清促性腺激素水平的“自发”增加，因为在LD 6：18 10周后去势，然后再暴露于LD 6：18 17周的仓鼠中，这些水平也逐渐增加。在长期暴露于LD 6：18的过程中，神经内分泌-睾丸轴的活动逐渐增加的观察结果向我们表明，仓鼠的生殖系统可能会变得对光刺激更敏感，随着先前暴露于非刺激性光周期的时间增加。为了检查这种可能性，将LD 6：18维持10或13.5周的仓鼠转移至LD 16：8维持3.5周，然后处死。在那些仓鼠暴露于非刺激光周期13.5周有一个更大的增加，睾丸大小光刺激后（5.5倍增加）比那些动物暴露仅10周（2.2倍增加）。在血清促性腺激素水平中观察到类似的模式，表明雄性仓鼠的神经内分泌-性腺轴对光刺激的敏感性随着暴露于非刺激性光周期的时间延长而增加。
Male golden hamsters were exposed to nonstimulatory short days for 25 weeks, and the effects on gonadal weight and serum gonadotropin levelswere assayed at biweekly intervals. Within 11 weeks afteranimals were transferred from a photostimulatory(LD 14: 10) to a nonstimulatory (LD 6: 18) lightcycle, serum LH and FSH titers, aswell astesticularweight had decreased markedly(4-, 5-and 13-fold, respectively). Continued exposure to LD 6: 18 resulted in gradual increases in serum gonadotropin levels and subsequently in the complete recrudescence(regrowth) of the testes by 25 weeks. The testis itself does not appear to be involved in the “spontaneous” increase in serum gonadotropin levels since these levels also increased gradually in hamsters that were castrated after 10 weeks of LD 6: 18 and then were exposed to LD 6: 18 for an additional 17 weeks. The observation of a gradual increase in the activity of the neuroendocrine-testicular axis during prolonged exposure to LD 6: 18 suggested to us that the hamster’s reproductive system might become more responsive to photostimulation with increasing length of prior exposure to nonstimulatory photoperiods. To examine this possibility hamsters maintained on LD 6: 18 for either 10 or 13.5 weeks were transferred to LD 16: 8 for 3.5 weeks, and then sacrificed. In those hamsters exposed to nonstimulatory photoperiods for 13.5 weeks there was a greater increase in testicular size after photostimulation(5.5-fold increase) than in those animals exposed for only 10 weeks (2.2-fold increase). A similar pattern was observed in serum gonadotropin levels, indicating that the neuroendocrine-gonadal axis of the male hamster increases in sensitivityto photostimula-lion with a longer exposure to nonstimulatory photoperiods.