Wollnik F, Turek F W
Department of Neurobiology and Physiology, Northwestern University, Evanston, IL 60208.
Physiol Behav. 1988;43(3):389-96. doi: 10.1016/0031-9384(88)90204-1.
Estrogen treatment alters the expression of ultradian activity rhythms in male and female LEW/Ztm rats. This finding raises the possibility that the expression of ultradian rhythms may vary on different days of the estrous cycle. To test this hypothesis, we recorded the circadian and ultradian wheel-running activity rhythms of entrained (LD 12:12) and free-running sexually mature LEW/Ztm females during their 4- or 5-day estrous cycle. The mean daily activity, the duration of activity, the circadian period of activity, and the occurrence of ultradian rhythms differed significantly among the days of the estrous cycle. In LD 12:12, the phase angle difference between the beginning of activity and light offset varied reliably in 5-day cycling animals. The highest daily mean of activity, the longest duration, and the shortest circadian period length were observed on the day of estrus in both entrained and free-running animals. The day of estrus was characterized by a constant high level of activity throughout the activity phase, while the days following ovulation showed a bi- or trimodal activity pattern. Power spectrum analysis revealed significant ultradian components for the days of metestrus and diestrus, but only circadian components for the days of proestrus and estrus. These results were interpreted as indicating that endogenous changes in circulating hormone levels can induce changes in the ultradian and circadian patterns of wheel-running activity in LEW/Ztm rats.
雌激素治疗会改变雄性和雌性LEW/Ztm大鼠超日活动节律的表达。这一发现增加了超日节律表达可能在发情周期的不同日子有所变化的可能性。为了验证这一假设，我们记录了处于4或5天发情周期的、已适应（12小时光照：12小时黑暗）和自由活动的性成熟LEW/Ztm雌性大鼠的昼夜和超日转轮活动节律。发情周期各天之间的日均活动量、活动持续时间、活动的昼夜周期以及超日节律的出现情况存在显著差异。在12小时光照：12小时黑暗条件下，5天周期的动物中，活动开始与光照结束之间的相位角差异有可靠变化。在已适应和自由活动的动物中，发情当天观察到最高的日均活动量、最长的持续时间和最短的昼夜周期长度。发情当天的特征是在整个活动阶段活动水平持续较高，而排卵后的日子则呈现双峰或三峰活动模式。功率谱分析显示，动情后期和间情期的日子有显著的超日成分，但发情前期和发情期的日子只有昼夜成分。这些结果被解释为表明循环激素水平的内源性变化可诱导LEW/Ztm大鼠转轮活动的超日和昼夜模式发生变化。
