Davis F C, Gorski R A
Department of Biology, University of Virginia, Charlottesville 22901.
J Comp Physiol A. 1988 Apr;162(5):601-10. doi: 10.1007/BF01342635.
During development, the circadian rhythms of rodents become entrained to rhythmicity of the mother. Rhythms in behavior and in neuroendocrine function are regulated by a circadian pacemaker thought to be located within the suprachiasmatic nucleus (SCN) of the hypothalamus. Evidence indicates that this pacemaker begins to function and to be entrained by maternal rhythms before birth. Although the maternal rhythms which mediate prenatal entrainment of the fetal circadian pacemaker have not been identified, it is likely that they are regulated by the maternal SCN. The role of the maternal SCN in entrainment of the offspring was examined in Syrian hamsters (Mesocricetus auratus) by measuring the activity/rest rhythms of pups. Using the synchrony among the rhythms of pups within a litter as an indication that the pups had been entrained, the effect on entrainment of ablating the maternal SCN was determined. Lesions of the maternal SCN which were performed early in gestation (day 7) and which destroyed at least 75% of the SCN were found to disrupt the normal within litter synchrony among pups, indicating interference with the normal mechanism of entrainment. The effect of lesions on day 7 of gestation could mean that the maternal SCN is important for entrainment of the pups before birth, after birth, or during both of these times. To determine if the maternal SCN is specifically important for prenatal entrainment, lesions were performed two days before birth on day 14 of gestation. Lesions of the maternal SCN on day 14 were not as disruptive as were lesions on day 7. This suggests that the maternal SCN is important between days 7 and 14 of gestation and that the synchrony normally observed at weaning is already established, in part, on or before day 14 of gestation. This further suggests that an entrainable circadian pacemaker is present in the fetus only two weeks after fertilization.
在发育过程中，啮齿动物的昼夜节律会与母体的节律同步。行为和神经内分泌功能的节律受一个昼夜节律起搏器调节，该起搏器被认为位于下丘脑的视交叉上核（SCN）内。有证据表明，这个起搏器在出生前就开始发挥作用并被母体节律同步。虽然尚未确定介导胎儿昼夜节律起搏器产前同步的母体节律，但它们很可能受母体SCN调节。通过测量幼崽的活动/休息节律，在叙利亚仓鼠（金仓鼠）中研究了母体SCN在子代同步中的作用。以一窝幼崽节律之间的同步性作为幼崽已被同步的指标，确定了切除母体SCN对同步的影响。发现在妊娠早期（第7天）进行的、破坏至少75% SCN的母体SCN损伤会破坏幼崽之间正常的窝内同步性，表明干扰了正常的同步机制。妊娠第7天损伤的影响可能意味着母体SCN对幼崽出生前、出生后或这两个时期的同步都很重要。为了确定母体SCN对产前同步是否特别重要，在妊娠第14天出生前两天进行了损伤。妊娠第14天母体SCN的损伤不像第7天的损伤那样具有破坏性。这表明母体SCN在妊娠第7天至14天之间很重要，并且断奶时通常观察到的同步性在妊娠第14天或之前就已部分建立。这进一步表明，受精后仅两周，胎儿体内就存在一个可同步的昼夜节律起搏器。
