Davis F C, Gorski R A
Laboratory of Neuroendocrinology of the Brain Research Institute, Los Angeles, California.
J Biol Rhythms. 1985;1(1):77-89. doi: 10.1177/074873048600100108.
Individual hamster pups were maintained in constant dim light from just prior to birth, and their circadian wheel-running activity rhythms were recorded beginning at 18 days of age. Records of the postweaning free-running activity rhythm were used to determine the phase of a pup's rhythm on the day of weaning. Two groups of pups (LD and DL) were born to mothers that had been entrained before birth to light-dark cycles 12 hr out of phase. Both groups of pups were raised in constant dim light by foster mothers that had been entrained to only one of the prenatal cycles (LD). Thus pups born to mothers from different cycles were exposed to identical rhythmic environments postnatally. Despite the similar postnatal treatment, the two groups of pups showed activity rhythms at weaning with very different phases. The LD pups, born to and raised by LD mothers, were approximately synchronous with one another and with their foster mothers. The DL pups, born to DL mothers, but raised by LD mothers, were not synchronous with one another or with their foster mothers. Half of the DL pups showed phases predicted by their prenatal treatment, but the other half showed scattered phases. The results demonstrate that phase at weaning is affected by prenatal rhythmicity, and suggest that the circadian pacemaker underlying the activity rhythm is already functional and entrained at, or before, birth.
从出生前开始，将每只仓鼠幼崽置于持续昏暗的光线下，并从18日龄开始记录它们的昼夜节律性轮转活动节律。断奶后自由活动节律的记录用于确定幼崽在断奶当天的节律相位。两组幼崽（LD组和DL组）的母亲在出生前被同步到相差12小时的明暗循环中。两组幼崽均由仅被同步到其中一个产前循环（LD循环）的代孕母亲在持续昏暗的光线下饲养。因此，来自不同循环的母亲所生的幼崽在出生后暴露于相同的节律环境中。尽管产后处理相似，但两组幼崽在断奶时表现出相位非常不同的活动节律。由LD母亲生育并抚养的LD组幼崽彼此之间以及与它们的代孕母亲大致同步。由DL母亲生育但由LD母亲抚养的DL组幼崽彼此之间以及与它们的代孕母亲不同步。一半的DL组幼崽表现出与其产前处理预测的相位，但另一半表现出分散的相位。结果表明，断奶时的相位受产前节律性的影响，并表明活动节律背后的昼夜节律起搏器在出生时或出生前就已经发挥功能并被同步。
