Center for Translational Social Neuroscience, Yerkes National Primate Research Center, Department of Psychiatry and Behavioral Sciences, Emory University, 954 Gatewood Rd, Atlanta, GA 30329, USA.
Psychoneuroendocrinology. 2011 Oct;36(9):1312-26. doi: 10.1016/j.psyneuen.2011.03.003. Epub 2011 Apr 9.
Activation of corticotrophin releasing factor (CRF) neurons in the paraventricular nucleus of the hypothalamus (PVN) is necessary for establishing the classic endocrine response to stress, while activation of forebrain CRF neurons mediates affective components of the stress response. Previous studies have reported that mRNA for CRF2 receptor (CRFR2) is expressed in the bed nucleus of the stria terminalis (BNST) as well as hypothalamic nuclei, but little is known about the localization and cellular distribution of CRFR2 in these regions. Using immunofluorescence with confocal microscopy, as well as electron microscopy, we demonstrate that in the BNST CRFR2-immunoreactive fibers represent moderate to strong labeling on axons terminals. Dual-immunofluorescence demonstrated that CRFR2-fibers co-localize oxytocin (OT), but not arginine-vasopressin (AVP), and make perisomatic contacts with CRF neurons. Dual-immunofluorescence and single cell RT-PCR demonstrate that in the hypothalamus, CRFR2 immunoreactivity and mRNA are found in OT, but not in CRF or AVP-neurons. Furthermore, CRF neurons of the PVN and BNST express mRNA for the oxytocin receptor, while the majority of OT/CRFR2 neurons in the hypothalamus do not. Finally, using adenoviral-based anterograde tracing of PVN neurons, we show that OT/CRFR2-immunoreactive fibers observed in the BNST originate in the PVN. Our results strongly suggest that CRFR2 located on oxytocinergic neurons and axon terminals might regulate the release of this neuropeptide and hence might be a crucial part of potential feedback loop between the hypothalamic oxytocin system and the forebrain CRF system that could significantly impact affective and social behaviors, in particular during times of stress.
促肾上腺皮质释放因子（CRF）神经元在下丘脑室旁核（PVN）的激活对于建立经典的应激内分泌反应是必要的，而前脑 CRF 神经元的激活则介导了应激反应的情感成分。先前的研究报告称，CRF2 受体（CRFR2）的 mRNA 表达在终纹床核（BNST）以及下丘脑核中，但对于这些区域中 CRFR2 的定位和细胞分布知之甚少。通过使用共聚焦显微镜的免疫荧光，以及电子显微镜，我们证明 BNST 中的 CRFR2-免疫反应性纤维代表中等至强标记的轴突末端。双重免疫荧光显示，CRFR2 纤维与催产素（OT）共定位，但不与精氨酸加压素（AVP）共定位，并与 CRF 神经元形成周质接触。双重免疫荧光和单细胞 RT-PCR 表明，在下丘脑，CRFR2 免疫反应性和 mRNA 存在于 OT 中，但不存在于 CRF 或 AVP 神经元中。此外，PVN 和 BNST 的 CRF 神经元表达催产素受体的 mRNA，而下丘脑的大多数 OT/CRFR2 神经元则不表达。最后，使用基于腺病毒的 PVN 神经元顺行示踪，我们表明 BNST 中观察到的 OT/CRFR2-免疫反应性纤维起源于 PVN。我们的结果强烈表明，位于催产素能神经元和轴突末端的 CRFR2 可能调节这种神经肽的释放，因此可能是下丘脑催产素系统和前脑 CRF 系统之间潜在反馈回路的关键部分，这可能会对情感和社交行为产生重大影响，特别是在应激期间。
