Fang J, Fishbein W
Department of Psychology, City College, City University of New York, NY 10031, USA.
Brain Res. 1996 Sep 23;734(1-2):275-85.
Previously, we reported that paradoxical sleep (PS) is sexually dimorphic in mice and rats. Since some early studies indicate that PS is suppressed during proestrus night, it is important to know whether the estrus cycle and accompanying circulating ovarian hormones could explain the sexual dimorphism of PS. To examine this, sleep patterns of male rats were compared with those of normal cycling female rats and ovariectomized females in a 12:12 h light/dark cycle. Slow wave sleep and total sleep time are indistinguishable between the males, cycling females and ovariectomized females. However, normal males display significantly more PS than cycling females during both daytime and nighttime (average of all estrus stages). On the other hand, while ovariectomy has no visible effect on daytime sleep--the sexual dimorphism of PS is unchanged by ovariectomy--during nighttime, ovariectomy produces a selective increase of PS, eliminating the sex difference during the night. In sum, normal cycling females show no change in daytime sleep patterns across the estrus cycle, but have significantly less PS during proestrus nights than during metestrus and diestrus nights. The results indicate that the sex difference in nighttime PS is due to the suppression of PS by ovarian hormones during proestrus and, to a less extent, estrus nights. The sex difference in daytime PS, on the other hand, appears to be independent of circulating ovarian hormones.
此前，我们报道过异相睡眠（PS）在小鼠和大鼠中存在性别差异。由于一些早期研究表明，在发情前期的夜晚，异相睡眠会受到抑制，因此了解发情周期以及随之而来的循环卵巢激素是否能够解释异相睡眠的性别差异就显得尤为重要。为了对此进行研究，我们在12:12小时的明暗周期下，将雄性大鼠的睡眠模式与正常处于发情周期的雌性大鼠以及卵巢切除的雌性大鼠的睡眠模式进行了比较。慢波睡眠和总睡眠时间在雄性、处于发情周期的雌性以及卵巢切除的雌性之间并无差异。然而，正常雄性在白天和夜间（所有发情阶段的平均值）的异相睡眠均显著多于处于发情周期的雌性。另一方面，虽然卵巢切除对白天睡眠没有明显影响——异相睡眠的性别差异不会因卵巢切除而改变——但在夜间，卵巢切除会导致异相睡眠选择性增加，从而消除了夜间的性别差异。总之，正常处于发情周期的雌性在整个发情周期中白天睡眠模式没有变化，但在发情前期的夜晚比在发情后期和间情期的夜晚异相睡眠显著减少。结果表明，夜间异相睡眠的性别差异是由于发情前期以及在较小程度上发情期夜晚卵巢激素对异相睡眠的抑制作用。另一方面，白天异相睡眠的性别差异似乎与循环卵巢激素无关。
