Elliott J A, Tamarkin L
Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950.
J Comp Physiol A. 1994 Apr;174(4):469-84. doi: 10.1007/BF00191713.
Circadian regulation of pineal melatonin content was studied in Syrian hamsters (Mesocricetus auratus), especially melatonin peak width and the temporal correlation to wheel-running activity. Melatonin was measured by radioimmunoassay in glands removed at different circadian times with respect to activity onset (= CT 12). Pineal melatonin peak width (h; for mean > or = 125 pg/gland) and activity duration (alpha) were both 4-5 h longer after 12 or 27 weeks than after 5 or 6 days in continuous darkness (DD). Increased peak width was associated with a delay in the morning decline (M) of melatonin to baseline, correlated with a similar delay in wheel-running offset. In contrast, the evening rise (E) in melatonin occurred at approximately the same circadian phase regardless of the length of DD. Fifteen min light pulses produced similar phase-shifts in melatonin and activity. In a phase advance shift, M advanced at once, while E advanced only after several days of adjustment. Independent timing of shifts in the E and M components of the melatonin rhythm suggest that these events are controlled separately by at least two circadian oscillators whose mutual phase relationship determines melatonin peak width. This two-oscillator control of melatonin peak width is integral to the circadian mechanism of hamster photoperiodic time measurement.
研究了叙利亚仓鼠（金仓鼠）松果体褪黑素含量的昼夜节律调节，特别是褪黑素峰值宽度以及与转轮活动的时间相关性。通过放射免疫分析法测定在相对于活动开始（= CT 12）的不同昼夜时间取出的腺体中的褪黑素。与在持续黑暗（DD）中5或6天后相比，12或27周后松果体褪黑素峰值宽度（小时；平均≥125 pg/腺体）和活动持续时间（α）均延长4 - 5小时。峰值宽度增加与褪黑素早晨降至基线的延迟（M）相关，这与转轮活动结束的类似延迟相关。相比之下，无论DD时长如何，褪黑素的傍晚升高（E）都发生在大致相同的昼夜阶段。15分钟的光脉冲在褪黑素和活动中产生类似的相移。在相位提前移位中，M立即提前，而E仅在几天的调整后才提前。褪黑素节律的E和M成分移位的独立定时表明，这些事件至少由两个昼夜振荡器分别控制，它们的相互相位关系决定了褪黑素峰值宽度。这种对褪黑素峰值宽度由两个振荡器的控制是仓鼠光周期时间测量昼夜机制的组成部分。
