Establishment of functional "hypothalms-thymus" axis at early stage of fetal life

本研究的目的是探讨下丘脑和胸腺之间的功能性“串扰”何时会在怀孕期间建立。取13 ~ 21日龄Wistar系胎鼠下丘脑和胸腺，进行雌激素受体（ER）和血清胸腺因子（FTS）的EIA测定，以及ER、FTS和促黄体激素释放激素（LHRH）的免疫组化染色。其浓度逐渐增加，直至妊娠结束。LHRH在第13天在胸腺中可检测到，而在第16天在下丘脑中则出现得更晚。ER、FTS和LHRH阳性细胞定位于下丘脑内侧视前区（MPOA）的双极神经元和胸腺髓质区的上皮细胞（TEC）。上述结果表明，胎儿血液循环中的雌激素通过其受体TEC和MPOA神经元调节FTS和LHRH的释放，提示功能性的“下丘脑-胸腺”轴在胎儿早期就已建立。

This study was aimed to examine when functional "crosstalk" between hypothalamus and thymus would be established during pregnancy. The hypothalamus and thymus from 13-to 21-day-old rat fetuses of Wistar strain were dissected out and then offered to (1) EIA assay of estrogen receptor (ER) and serum thymic factor (FTS) , and (2) immunohistochemical staining of ER,FTS and luteinizing hormone releasing hormone (LHRH) .ER and FTS were detectable at the 13th day of gestation, and their concentrations gradually increased until the end of gestation. LHRH was detectable in the thymus at the 13th day, wheras it appeared much later in the hypothalamus at the 16th day. ER-, FTS- and LHRH-positive cells were localized in the epithelial cells (TEC) in the thymic medullary region and the bipolar neurons in the medial preoptic area (MPOA) of the hypothalamus. In adition, all ER-, FTS-, and LHRH-positive cells in the respective tissue areas were identical with each other.It is clear from the above results that estrogen in the fetal blood circulation modulate through its receptor TEC and MPOA-neurons to release FTS and LHRH,suggesting that the functional "hypothalamus-thymus" axis is established at the early stage of the fetal life.