THYROID HORMONE INFLUENCES ON SYMPATHETIC NEURON

在出生前和出生后的生活中，有很多因素 它们塑造了发育中的神经系统。在这些因素中 是母体和母体同时产生的激素吗？ 胎儿或新生儿本身。其中几种荷尔蒙， 包括甲状腺激素，已经被证明起着关键作用 在调节神经发育和随后的行为中的作用 和学习能力。这项研究的总体目标是 研究甲状腺激素对心脏功能的重要调节作用 神经系统的发育。这种荷尔蒙已经被证明 调节不同区域神经元发育的各个方面 神经系统的一部分。甲状腺激素缺乏症 发育的关键时期会产生严重的损害 精神功能(克汀病)。为了理解 更好地了解神经元发育的具体方面 受甲状腺状态异常的影响，我们将聘请 发展中的神经系统，不同于更复杂的 中枢神经系统的各个区域，精确的分析可以 由在此期间产生的神经元的数量组成 增殖，在随后的过程中丢失的神经元的数量 自然发生的神经元死亡的周期，数量 突触的形成和树突的成熟 树。所使用的神经系统是最好的 大鼠颈交感神经节(SCG)。该系统可以 作为一种灵敏的形态分析方法来检测这些效应 在两个危急时刻荷尔蒙水平的变化 发展。第一个临界期是神经元期 增殖，这在大鼠的SCG中发生在胚胎之间 第15天和出生。第二阶段是快速发展时期。 发生在出生和第三个孩子之间的突触发生 出生后一周。这一时期也与 SCG中正常发生的神经元死亡。

During both prenatal and postnatal life, there are many factors which shape the developing nervous system. Among these factors are the hormones which are produced both by the mother and by the fetus or neonate itself. Several of these hormones, including thyroid hormone, have been shown to play critical roles in regulating neural development, and subsequent behavior and learning ability. The overall aim of the study is to examine the critical regulatory role of thyroid hormone on the development of the nervous system. This hormone has been shown to regulate aspects of neuronal development in various regions of the nervous system. Deficiencies of thyroid hormone during critical periods of development produce a profound impairment of mental functioning (Cretinism). In order to understand better the specific aspects of neuronal development which are affected by abnormal thyroid states, we will employ a developing neuronal system in which, unlike in more complex regions of the central nervous system, precise analyses can be made of the number of neurons produced during the period of proliferation, the number of neurons lost during the subsequent period of naturally occurring neuron death, the number of synapses which are formed, and the maturation of the dendritic tree. The neuronal system to be employed is the superior cervical sympathetic ganglion (SCG) of the rat. This sytem may be employed as a sensitive morphological assay for the effects of altered hormonal levels during two critical times during development. The first critical time is the period of neuronal proliferation, which in the rat SCG occurs between embryonic day 15 and birth. The second is the period of rapid synaptogenesis, which occurs between birth and the third postnatal week. This period also coincides with the period of normally occurring neuronal death in the SCG.