Rapid phase adjustment of melatonin and core body temperature rhythms following a 6-h advance of the light/dark cycle in the horse.
Rapid phase adjustment of melatonin and core body temperature rhythms following a 6-h advance of the light/dark cycle in the horse.
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DOI：
10.1186/1740-3391-5-5
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发表时间：
2007-08-24
影响因子：
--
通讯作者：
Fitzgerald BP
中科院分区：
文献类型：
--
作者：
Murphy BA;Elliott JA;Sessions DR;Vick MM;Kennedy EL;Fitzgerald BP
跨多个时区的快速位移导致新的光明和黑暗周期与先前携带的内部生物钟程序之间的冲突，这种现象被称为时差。在人类中，时差反应通常表现为不适、食欲不振、疲劳、睡眠障碍和表现缺陷，其后果对于希望在国际目的地表现最佳的运动员来说尤其重要。作为一个以运动能力而闻名的物种，时差反应的后果也与马有关。然而，时差相关的昼夜节律紊乱的持续时间和严重程度目前尚不清楚。我们调查了血清褪黑激素和核心体温（BT）的节奏突然6小时的LD周期提前在马的再夹带率。六个健康的，2岁的成年人夹带到12小时光/12小时黑暗（LD 12：12）的自然光周期被安置在一个避光畜棚下的照明时间表，模仿外部LD周期。在第0天基线采样后，通过提前6小时结束随后的黑暗期，完成LD周期的提前偏移。每隔3小时采集血样，进行血清褪黑激素分析和BT读数，每隔一天采集24小时，共11天。使用重复测量方差分析和余弦曲线拟合参数分析评估对随后的褪黑激素和BT 24小时节律的干扰。我们证明，马褪黑激素的节奏重新夹带迅速到6小时的相位提前LD 12：12光周期。褪黑激素的相移在新时间表的第一天完全完成，此后节律相位和波形稳定。相比之下，BT节律的提前在第三天实现，然而BT节律波形，特别是其中间值，在LD移位后的许多天内发生改变。除了温度节律的破坏，褪黑激素节律的快速抑制表明，马的中央昼夜节律起搏器可能具有特别强大的夹带反应。对运动成绩的影响仍然未知。
Rapid displacement across multiple time zones results in a conflict between the new cycle of light and dark and the previously entrained program of the internal circadian clock, a phenomenon known as jet lag. In humans, jet lag is often characterized by malaise, appetite loss, fatigue, disturbed sleep and performance deficit, the consequences of which are of particular concern to athletes hoping to perform optimally at an international destination. As a species renowned for its capacity for athletic performance, the consequences of jet lag are also relevant for the horse. However, the duration and severity of jet lag related circadian disruption is presently unknown in this species. We investigated the rates of re-entrainment of serum melatonin and core body temperature (BT) rhythms following an abrupt 6-h phase advance of the LD cycle in the horse. Six healthy, 2 yr old mares entrained to a 12 h light/12 h dark (LD 12:12) natural photoperiod were housed in a light-proofed barn under a lighting schedule that mimicked the external LD cycle. Following baseline sampling on Day 0, an advance shift of the LD cycle was accomplished by ending the subsequent dark period 6 h early. Blood sampling for serum melatonin analysis and BT readings were taken at 3-h intervals for 24 h on alternate days for 11 days. Disturbances to the subsequent melatonin and BT 24-h rhythms were assessed using repeated measures ANOVA and analysis of Cosine curve fitting parameters. We demonstrate that the equine melatonin rhythm re-entrains rapidly to a 6-h phase advance of an LD12:12 photocycle. The phase shift in melatonin was fully complete on the first day of the new schedule and rhythm phase and waveform were stable thereafter. In comparison, the advance in the BT rhythm was achieved by the third day, however BT rhythm waveform, especially its mesor, was altered for many days following the LD shift. Aside from the temperature rhythm disruption, rapid resynchronization of the melatonin rhythm suggests that the central circadian pacemaker of the horse may possess a particularly robust entrainment response. The consequences for athletic performance remain unknown.