Campeau S, Watson S J
Mental Health Research Institute, The University of Michigan, Ann Arbor 48109-0720, USA.
J Comp Neurol. 2000 Jul 31;423(3):474-91.
Prior studies in our laboratory demonstrated that part of the thalamus is necessary for activating the hypothalamo-pituitary-adrenocortical (HPA) axis in response to audiogenic stress in rats. The present studies were designed to determine how the auditory-responsive thalamic nuclei might activate the HPA axis. Both retrograde [Fluoro-Gold (FG)] and anterograde [Phasoleus vulgaris-leucoagglutinin (PHA-L) and biotinylated dextran amines (BDA)] tracers were employed to study the putative connectivity between the thalamus and the medial parvocellular region of the hypothalamic paraventricular nucleus (PAmp). In addition, rats receiving FG in the PAmp were subjected to audiogenic stress, and the distribution of both FG and the protein product of the immediate-early gene c-fos, Fos, were determined by double immunohistochemistry, to help assess putative functional links between the auditory-responsive thalamic nuclei and PAmp. The results of PAmp FG placement indicated retrogradely labeled cells in several areas, including the bed nucleus of the stria terminalis, hypothalamic regions, the supramammillary nucleus, some thalamic regions, and importantly, a few multisensory nuclei of the thalamus, including the parvicellular division of the subparafascicular and posterior intralaminar nuclei. Injections of the tracers PHA-L or BDA into these auditory-responsive posterior thalamic nuclei provided further evidence of projections to the PAmp. In addition, several forebrain areas were observed to receive moderate to heavy innervation. These areas included most of the regions described above, which, in turn, project to the PAmp. Because cells in the multisensory thalamic nuclei, hypothalamic, and forebrain areas were double labeled with FG and Fos, the results suggest that either direct projections from the thalamus to PAmp neurons, or indirect projections from the thalamus to stress-responsive forebrain areas projecting to the PAmp, might mediate activation of the HPA axis by audiogenic stress.
我们实验室之前的研究表明，丘脑的一部分对于激活大鼠听源性应激反应中的下丘脑 - 垂体 - 肾上腺皮质（HPA）轴是必要的。本研究旨在确定听觉反应性丘脑核如何激活HPA轴。逆行示踪剂[荧光金（FG）]和顺行示踪剂[菜豆白细胞凝集素（PHA - L）和生物素化葡聚糖胺（BDA）]均被用于研究丘脑与下丘脑室旁核内侧小细胞区（PAmp）之间的假定连接。此外，在PAmp中接受FG注射的大鼠接受听源性应激，通过双重免疫组织化学确定FG和即刻早期基因c - fos的蛋白质产物Fos的分布，以帮助评估听觉反应性丘脑核与PAmp之间的假定功能联系。PAmp中FG注射的结果表明，在几个区域有逆行标记的细胞，包括终纹床核、下丘脑区域、乳头体上核、一些丘脑区域，重要的是，还有丘脑的一些多感觉核，包括束旁核小细胞部和板内核后部。将示踪剂PHA - L或BDA注入这些听觉反应性丘脑后核，为向PAmp的投射提供了进一步的证据。此外，观察到几个前脑区域接受中度至重度的神经支配。这些区域包括上述大多数区域，而这些区域又投射到PAmp。由于多感觉丘脑核、下丘脑和前脑区域的细胞被FG和Fos双重标记，结果表明，要么是丘脑向PAmp神经元的直接投射，要么是丘脑向投射到PAmp的应激反应性前脑区域的间接投射，可能介导听源性应激对HPA轴的激活。
