Doetsch G S, Norelle A, Mark E K, Standage G P, Lu S M, Lin R C
Department of Surgery, Section of Neurosurgery, Medical College of Georgia, Augusta 30912.
Brain Res Bull. 1993;31(5):553-63. doi: 10.1016/0361-9230(93)90123-s.
Immunocytochemical methods were used to determine the distributions of glutamic acid decarboxylase (GAD), vasoactive intestinal polypeptide (VIP), cholecystokinin (CCK), and somatostatin (SOM) in the primary somatosensory cortex and somatosensory thalamus of adult raccoons. The cortex showed extensive immunoreactivity for GAD, revealing a large population of GABAergic neurons. GAD-labeled cells were numerous in all cortical layers, but were most concentrated in laminae II-IV. The cells were nonpyramidal and of varying morphology, typically with somata of small or medium size. GAD-immunoreactive puncta, presumably synaptic terminals, were widespread and often appeared to end on both GAD-negative and GAD-positive neurons. Immunoreactivity for the peptides was much less extensive than that for GAD, with the number of labeled neurons for VIP > CCK > SOM. Peptidergic cells were preferentially located in the upper and middle cortical layers, especially laminae II and III. The cells were nonpyramidal, often bitufted or bipolar in morphology, and small to medium in size. Their processes formed diffuse plexuses of fibers with terminal-like varicosities that occasionally surrounded nonpeptidergic neurons. The thalamus showed a clearly differentiated pattern of immunoreactivity for GAD, but little or no labeling for the three peptides. Nuclei adjoining the ventral posterior lateral (VPL)/ventral posterior medial (VPM) complex--including the reticular nucleus--contained many GAD-positive neurons and fibers. In contrast, the VPL and VPM nuclei displayed considerably less GAD immunoreactivity, somewhat surprising given the raccoon's highly developed somatosensory system. However, the ventral posterior inferior (VPI) nucleus revealed rather dense GAD labeling, perhaps related to a specialized role in sensory information processing. Thus, the primary somatosensory cortex of the raccoon showed patterns of immunoreactivity for GAD and peptides that were similar to those of other species; the somatosensory thalamus revealed a distinctive profile of GAD immunoreactivity, with labeling that was light to moderate in the VPL/VPM complex and relatively extensive in VPL.
采用免疫细胞化学方法，确定成年浣熊初级体感皮层和体感丘脑内谷氨酸脱羧酶（GAD）、血管活性肠多肽（VIP）、胆囊收缩素（CCK）和生长抑素（SOM）的分布情况。皮层对GAD呈现广泛的免疫反应性，显示出大量的γ-氨基丁酸能神经元。GAD标记的细胞在所有皮层层中都很多，但最集中在II-IV层。这些细胞是非锥体神经元，形态各异，通常具有小或中等大小的胞体。GAD免疫反应性小点，推测为突触终末，广泛分布，且常终止于GAD阴性和GAD阳性神经元上。肽类的免疫反应性比GAD的免疫反应性范围小得多，VIP标记神经元数量>CCK标记神经元数量>SOM标记神经元数量。肽能细胞优先位于皮层上层和中层，尤其是II层和III层。这些细胞是非锥体神经元，形态上常为双簇状或双极状，大小为小到中等。它们的突起形成弥漫性纤维丛，带有类似终末的膨体，偶尔围绕非肽能神经元。丘脑对GAD的免疫反应性呈现明显不同的模式，但对这三种肽几乎没有或没有标记。与腹后外侧（VPL）/腹后内侧（VPM）复合体相邻的核团——包括网状核——含有许多GAD阳性神经元和纤维。相比之下，VPL和VPM核显示出的GAD免疫反应性要少得多，考虑到浣熊高度发达的体感系统，这有点令人惊讶。然而，腹后下核（VPI）显示出相当密集的GAD标记，这可能与它在感觉信息处理中的特殊作用有关。因此，浣熊的初级体感皮层对GAD和肽类的免疫反应性模式与其他物种相似；体感丘脑显示出独特的GAD免疫反应性特征，在VPL/VPM复合体中标记为轻度到中度，在VPI中相对广泛。
