Kirouac Gilbert J, Parsons Matthew P, Li Sa
Division of Basic Medical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada.
Brain Res. 2005 Oct 19;1059(2):179-88. doi: 10.1016/j.brainres.2005.08.035. Epub 2005 Oct 5.
The paraventricular nucleus of the thalamus (PVT) is a midline thalamic nucleus with projections to limbic forebrain areas such as the nucleus accumbens and amygdala. The orexin (hypocretin) peptides are synthesized in hypothalamic neurons that project throughout the CNS. The present experiments were done to describe the extent of orexin fiber innervation of the PVT in comparison to other midline and intralaminar thalamic nuclei and to establish the location and proportion of orexin neurons innervating the PVT. All aspects of the anteroposterior PVT were found to be densely innervated by orexin fibers with numerous enlargements that also stained for synaptophysin, a marker for synaptic vesicle protein associated with pre-synaptic sites. Small discrete injections of cholera toxin B into the PVT of rats resulted in the retrograde labeling of a relatively small number of orexin neurons in the medial and lateral hypothalamus. The results also showed a lack of topographical organization among orexin neurons projecting to the PVT. Previous studies indicate that orexin neurons and neurons in the PVT appear to be most active during periods of arousal. Therefore, orexin neurons and their projections to the PVT may be part of a limbic forebrain arousal system.
丘脑室旁核（PVT）是丘脑的一个中线核团，它投射到诸如伏隔核和杏仁核等边缘前脑区域。食欲素（下丘脑泌素）肽由投射至整个中枢神经系统的下丘脑神经元合成。开展本实验是为了描述与其他中线和板内核团相比，食欲素纤维对PVT的支配范围，并确定支配PVT的食欲素神经元的位置和比例。发现PVT前后部的各个方面均被食欲素纤维密集支配，有许多增大区域，这些区域也被突触素染色，突触素是一种与突触前位点相关的突触小泡蛋白标记物。向大鼠PVT内小剂量离散注射霍乱毒素B，导致下丘脑内侧和外侧相对少量的食欲素神经元出现逆行标记。结果还显示，投射至PVT的食欲素神经元之间缺乏拓扑组织。先前的研究表明，食欲素神经元和PVT中的神经元在觉醒期间似乎最为活跃。因此，食欲素神经元及其向PVT的投射可能是边缘前脑觉醒系统的一部分。
