Honma K I, Hiroshige T
Am J Physiol. 1978 Nov;235(5):R250-6. doi: 10.1152/ajpregu.1978.235.5.R250.
Circadian rhythms of locomotor activity, body temperature, and plasma corticosterone were determined simultaneously in individual rats that were exposed to 200 lx continuous light for over 3 mo. Free-running circadian rhythms of locomotor activity persisted for about 2 mo under continuous light and then the rhythms gradually decomposed. After 3 mo of exposure, circadian rhythms disappeared and activity bursts of 1- to 2-h duration manifested themselves several times during a 24-h period. Body temperature also exhibited several bursts of fluctuation and these bursts were closely correlated in their temporal sequence with those of locomotor activity. A least-squares spectrum analysis revealed that the burst had regular 4- to 6-h periods. Plasma corticosterone, determined by serial sampling at 2-h intervals from individual rats, also exhibited several secretion episodes in a day. These episodic secretions synchronized with bursts of locomotor activity. These results suggest that the ultradian component, manifested under prolonged continuous light, is a fundamental unit of the circadian rhythm and an oscillator for the ultradian rhythm is common to the three functions examined.
在暴露于200勒克斯连续光照超过3个月的个体大鼠中，同时测定了运动活动、体温和血浆皮质酮的昼夜节律。在连续光照下，运动活动的自由运行昼夜节律持续约2个月，然后节律逐渐分解。暴露3个月后，昼夜节律消失，在24小时内出现了几次持续1至2小时的活动爆发。体温也表现出几次波动爆发，这些爆发在时间顺序上与运动活动的爆发密切相关。最小二乘谱分析表明，这些爆发具有规则的4至6小时周期。通过每隔2小时对个体大鼠进行连续采样测定的血浆皮质酮，在一天中也表现出几次分泌发作。这些间歇性分泌与运动活动的爆发同步。这些结果表明，在长时间连续光照下表现出的超日节律成分是昼夜节律的基本单位，并且所研究的三种功能具有共同的超日节律振荡器。
