Garza R, Puymirat J, Dussault J H
Unité de recherche en Ontogénèse et Génétique moléculaire, Centre Hospitalier de l'Université Laval, Québec, Canada.
Neuroscience. 1990;36(2):473-82. doi: 10.1016/0306-4522(90)90441-6.
A monoclonal antibody against the rat liver L-tri-iodothyronine nuclear receptor and acetylcholinesterase cytochemistry were used for the localization of thyroid hormone nuclear receptors in acetylcholinesterase-positive cell nuclei in fetal rat cerebral hemisphere neuronal cultures. After 3 days in vitro, the ratio of acetylcholinesterase-positive cells that were immunoreactive for the thyroid hormone nuclear receptor to those not stained for this receptor (74-26%, respectively) remains unchanged despite an increase in the number of acetylcholinesterase-positive cells with time (from day 3 to day 21) in culture. Furthermore, the addition of 3 X 10(-8) L-tri-iodothyronine in culture did not modify this ratio or have an effect on the number of acetylcholinesterase-positive cells, but significantly increased the neurite density in those acetylcholinesterase-positive cells that were immunoreactive for the thyroid hormone receptor. Conversely, no difference in the neurite densities of those acetylcholinesterase-positive cells not stained for this receptor was observed when cultured in the presence or absence of thyroid hormone. In other experiments with the same fetal brain cultures, treatment of cultures for 8 days with L-tri-iodothyronine, beginning on culture day 20, demonstrated the presence of a critical period which occurs in vitro around day 20, since the stimulatory effect of L-tri-iodothyronine on immunoreactive acetylcholinesterase-positive cell neurite density is lost after 20 days in vitro. These results demonstrate, for the first time, the presence of L-tri-iodothyronine nuclear receptors in fetal rat acetylcholinesterase-positive neurons and the existence of a cellular heterogeneity in the distribution of the thyroid hormone receptor. The presence of these receptors in fetal brain acetylcholinesterase-positive neurons suggests that some effects of L-tri-iodothyronine on the maturation of a subpopulation of acetylcholinesterase-positive neurons may result from a direct effect of this hormone through an interaction with its specific nuclear receptors.
利用一种抗大鼠肝脏L-三碘甲状腺原氨酸核受体的单克隆抗体和乙酰胆碱酯酶细胞化学方法，对胎鼠大脑半球神经元培养物中乙酰胆碱酯酶阳性细胞核内的甲状腺激素核受体进行定位。体外培养3天后，对甲状腺激素核受体呈免疫反应的乙酰胆碱酯酶阳性细胞与未被该受体染色的细胞之比（分别为74% - 26%）保持不变，尽管培养过程中（从第3天到第21天）乙酰胆碱酯酶阳性细胞数量随时间增加。此外，在培养物中添加3×10⁻⁸的L-三碘甲状腺原氨酸并未改变该比例，也未对乙酰胆碱酯酶阳性细胞数量产生影响，但显著增加了对甲状腺激素受体呈免疫反应的那些乙酰胆碱酯酶阳性细胞的神经突密度。相反，在有或无甲状腺激素的情况下培养时，未被该受体染色的那些乙酰胆碱酯酶阳性细胞的神经突密度未观察到差异。在对相同胎脑培养物进行的其他实验中，从培养第20天开始用L-三碘甲状腺原氨酸处理培养物8天，结果表明存在一个关键时期，该时期在体外大约第20天出现，因为体外培养20天后，L-三碘甲状腺原氨酸对免疫反应性乙酰胆碱酯酶阳性细胞神经突密度的刺激作用消失。这些结果首次证明胎鼠乙酰胆碱酯酶阳性神经元中存在L-三碘甲状腺原氨酸核受体，以及甲状腺激素受体分布存在细胞异质性。这些受体在胎脑乙酰胆碱酯酶阳性神经元中的存在表明，L-三碘甲状腺原氨酸对乙酰胆碱酯酶阳性神经元亚群成熟的某些影响可能是该激素通过与其特异性核受体相互作用产生的直接效应。
