Carmichael M S, Nelson R J, Zucker I
Proc Natl Acad Sci U S A. 1981 Dec;78(12):7830-4. doi: 10.1073/pnas.78.12.7830.
Running activity onset and estrous onset were recorded for hamsters exposed to progressively shorter daily light/dark (T) cycles. The period of the estrous cycle was a quadruple multiple of the period of the activity rhythm during entrainment to T cycles of 23.5-21.5 hr. There was no evidence of desynchronization of the activity and estrus rhythms. The very short estrous periods shown during exposure to short T cycles indicate that an intrinsic 96-hr interval for ovarian follicular maturation does not determine the period of the estrous cycle. Dissociation of estrous and running activity onsets occurred for all hamsters: estrous onset generally preceded running activity onset for T greater than or equal to 23.0 hr; for shorter T cycles, estrous onset generally lagged behind running activity onset. Wheel-running activity was intermittently split into entrained and free-running components for one female: at T = 22.0 hr, estrous onset was coupled first with one and then with the other of the split activity components. These findings suggest that two or more separate circadian oscillators may control timing of the activity and estrous rhythms.
记录了暴露于逐渐缩短的每日光照/黑暗（T）周期下的仓鼠的跑步活动起始时间和发情起始时间。在同步于23.5 - 21.5小时的T周期期间，发情周期的时长是活动节律时长的四倍。没有证据表明活动节律和发情节律不同步。在暴露于短T周期期间出现的极短发情期表明，卵巢卵泡成熟的内在96小时间隔并不决定发情周期的时长。所有仓鼠的发情起始时间和跑步活动起始时间都出现了分离：当T大于或等于23.0小时时，发情起始时间通常先于跑步活动起始时间；对于更短的T周期，发情起始时间通常落后于跑步活动起始时间。对于一只雌性仓鼠，轮转跑步活动间歇性地分为同步和自由运行部分：在T = 22.0小时时，发情起始时间首先与其中一个分离的活动部分同步，然后又与另一个同步。这些发现表明，可能有两个或更多独立的昼夜节律振荡器控制着活动节律和发情节律的时间安排。
