Weaver D R, Reppert S M
Laboratory of Developmental Chronobiology, Massachusetts General Hospital, Boston 02114.
Brain Res Dev Brain Res. 1989 May 1;47(1):151-5. doi: 10.1016/0165-3806(89)90119-3.
The primary neural pathway for entrainment of circadian rhythms in rodents is the retinohypothalamic tract, which conveys lighting information from the retina to a biological clock in the hypothalamic suprachiasmatic nuclei (SCN). In a precocious rodent species, the spiny mouse, the retinohypothalamic tract is present and functioning within the SCN on the day of birth, as assessed by HRP histochemistry and 14C-labeled 2-deoxyglucose autoradiography, respectively. Furthermore, direct perception of environmental lighting was observed in fetal spiny mice late in gestation. Direct, retina-mediated fetal light perception appears to be a less potent entraining agent than maternal cues communicating time-of-day information to the fetal spiny mouse. Nevertheless, direct fetal light perception may reinforce maternal entraining signals during the prenatal period and therefore be of physiological significance for entrainment of circadian rhythmicity in the fetus.
啮齿动物昼夜节律同步的主要神经通路是视网膜下丘脑束，它将视网膜的光照信息传递到下丘脑视交叉上核（SCN）中的生物钟。在一种早熟的啮齿动物——刺毛鼠中，通过HRP组织化学和14C标记的2-脱氧葡萄糖放射自显影分别评估发现，视网膜下丘脑束在出生当天就已存在于SCN内并发挥作用。此外，在妊娠后期的胎儿刺毛鼠中观察到了对环境光照的直接感知。直接的、视网膜介导的胎儿光感知似乎不如向胎儿刺毛鼠传递昼夜时间信息的母体线索那样强大的同步因子。然而，胎儿直接的光感知可能在产前阶段增强母体的同步信号，因此对于胎儿昼夜节律的同步具有生理意义。
