Langub M C, Maley B E, Watson R E
Department of Anatomy and Neurobiology, University of Kentucky Medical Center, Lexington 40536-0084.
Brain Res. 1994 Apr 4;641(2):303-10. doi: 10.1016/0006-8993(94)90159-7.
This study examined the hypothesis that synaptic relationships change on a daily basis in the anterior preoptic area of the intact, cycling female rat. Specifically, the anteroventral periventricular nucleus (AVPv) was chosen for analysis due to its abundant estrogen- and progesterone-receptive neurons and its critical role in the control of gonadotropin secretion. Ultrastructural analysis revealed that in the 24 h between proestrus and estrus, there was a 39% increase in axosomatic synapses upon AVPv neurons. In the subsequent 24 h to metestrus, the number of synapses decreased by 22%. Additional data showed that ovariectomy resulted in more axosomatic synapses in the AVPv relative to proestrus (46%) and metestrus (35%). Another component of the study investigated synaptic relationships on estrogen receptor-immunoreactive (ER-ir) and non-ER-ir neurons across the estrous cycle. ER-ir neurons received significantly more synaptic input at proestrus and estrus than did non-ER-ir neurons. At metestrus and following ovariectomy, no significant differences were present. The present study indicates that estrous cycle-associated synaptic plasticity occurs in the AVPv and lends further support to the critical role of this nucleus in regulation of gonadotropin secretion. Moreover, it provides the first evidence that ER- and non-ER-ir neurons are differentially innervated.
本研究检验了一个假说，即在完整的、处于发情周期的雌性大鼠的视前区前部，突触关系每天都会发生变化。具体而言，选择腹内侧视前核（AVPv）进行分析，是因为其含有丰富的雌激素和孕激素受体神经元，且在促性腺激素分泌的控制中起关键作用。超微结构分析显示，在发情前期和发情期之间的24小时内，AVPv神经元的轴体突触增加了39%。在随后到发情后期的24小时内，突触数量减少了22%。其他数据表明，相对于发情前期（46%）和发情后期（35%），去卵巢导致AVPv中轴体突触增多。该研究的另一个部分调查了发情周期中雌激素受体免疫反应性（ER-ir）和非ER-ir神经元上的突触关系。ER-ir神经元在发情前期和发情期比非ER-ir神经元接受的突触输入显著更多。在发情后期和去卵巢后，没有显著差异。本研究表明，发情周期相关的突触可塑性发生在AVPv中，并进一步支持了该核团在促性腺激素分泌调节中的关键作用。此外，它提供了首个证据，即ER-ir和非ER-ir神经元接受的神经支配存在差异。
