Mechanisms of Maternal Transfer of Photoperiodic Information

在包括人类在内的许多物种中，怀孕女性体内激素水平和新陈代谢的变化会影响胎儿的发育。胎儿发育的这些变化可能是对环境中正常波动的适应性反应以及母亲注射的化学物质的致畸效应造成的。事实上，尼古丁、可卡因和酒精的毒性效应是因为它们干扰了调节胎儿发育的正常生化途径，这些途径类似于生物体正常适应反应所使用的途径。霍顿博士将研究母体系统在怀孕期间向胎儿传递有关日长变化的信息的机制，这是一种自然产生的环境信号。众所周知，出生前的光周期信息影响出生后的生长速度、体重和生殖发育。她提出，松果体产生和分泌的一种激素--褪黑素可能是这种信息传递的候选者，因为它通过胎盘从母体循环到胎儿循环，并参与昼夜节律的调节。使用一种创新的技术程序，以一种具有生理意义的方式管理褪黑素，霍顿博士将识别母体系统中向胎儿传递全天信息的那些因素。这些基础研究的结果将有助于更好地理解母体系统可以改变正在展开的调节胎儿发育的内在遗传程序的机制。

Changes in hormone levels and metabolism in pregnant females in a number of species, including humans, can influence the development of the fetus. These changes in fetal development can result from adaptive responses to normal fluctuations in the environment as well as from the teratogenic effects of chemicals injected by the mother. Indeed the toxic effects of nicotine, cocaine and alcohol result from their interference with the normal biochemical pathways that regulate fetal development, pathways similar to those used in an organism's normal adaptive response. Dr. Horton will examine the mechanisms by which the maternal system transmits information about changes in day length, a naturally occurring environmental cue, to the fetus during gestation. It is known that prenatal photoperiodic information influences postnatal rate of growth, body weight and reproductive development. She proposes that melatonin, a hormone produced and secreted by the pineal gland, is a likely candidate for this transfer of information since it crosses the placenta from the maternal to the fetal circulation and is involved in regulation of circadian rhythmicity. Using an innovative technical procedure to administer melatonin in a physiologically meaningful manner, Dr. Horton will identify those factors in the maternal system which communicate day length information to the fetus. The results of these fundamental studies will lead to a better understanding of the mechanism by which the maternal system can alter the unfolding intrinsic genetic program regulating the development of the fetus.