Pre- and postsynaptic localization of the 5-HT7 receptor in rat dorsal spinal cord:: Immunocytochemical evidence
Pre- and postsynaptic localization of the 5-HT7 receptor in rat dorsal spinal cord:: Immunocytochemical evidence
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DOI：
10.1002/cne.20667
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发表时间：
2005-09-26
影响因子：
2.5
通讯作者：
Conrath, M
中科院分区：
文献类型：
--
作者：
Doly, S;Fischer, J;Conrath, M
一些证据表明，5-HT7受体参与了脊髓水平的疼痛控制，尽管其作用机制尚不清楚。为了了解5-羟色胺对该受体的作用，我们对5-HT7受体在腰椎水平的分布进行了免疫细胞化学研究。5-HT7免疫标记主要定位于背角的两个浅层和中小型背根神经节细胞，这与其在伤害性感受中的主要作用相一致。此外，在腰椎背外侧核(Onuf核)发现中等标记，提示参与盆底肌肉的控制。对背角的电子显微镜观察发现三个主要定位：1)突触后定位于I-III板层和许多树突中的多肽能细胞体；2)突触前定位于无髓鞘和细小的有髓多肽能纤维(观察到两种类型的轴突终末，大的轴突终末可能来自初级传入细胞，较小的轴突终末部分来自内部细胞；这种突触前标记分别占I和II层总标记的60%和22%)；3)在星形胶质细胞中观察到16.9%的I层和19.8%的II层的标记。标记的星形胶质细胞要么与神经元成分混合，要么在血管上形成星形细胞的“脚”。在树突中，标记定位于突触分化，提示5-羟色胺可能作用于5-HT7受体。这一定位与其他5-羟色胺受体定位进行了比较，并讨论了它们的生理后果。
Several lines of evidence indicate that 5-HT7 receptors are involved in pain control at the level of the spinal cord, although their mechanism of action is poorly understood. To provide a morphological basis for understanding the action of 5-HT on this receptor, we performed an immunocytochemical study of 5-HT7 receptor distribution at the lumbar level. 5-HT7 immunolabelling is localized mainly in the two superficial laminae of the dorsal horn and in small and medium-sized dorsal root ganglion cells, which is consistent with a predominant role in nociception. In addition, moderate labelling is found in the lumbar dorsolateral nucleus (Onuf's nucleus), suggesting involvement in the control of pelvic floor muscles. Electron microscopic examination of the dorsal horn revealed three main localizations: 1) a postsynaptic localization on peptidergic cell bodies in laminae I-III and in numerous dendrites; 2) a presynaptic localization on unmyelinated and thin myelinated peptidergic fibers (two types of axon terminals are observed, large ones, presumably of primary afferent origin, and smaller ones partially from intrinsic cells; this presynaptic labelling represents 60% and 22% of total labelling in laminae I and II, respectively); and 3) 16.9% of labelling in lamina I and 19.8% in lamina II are observed in astrocytes. Labeled astrocytes are either intermingled with neuronal elements or make astrocytic "feet" on blood vessels. In dendrites, the labelling is localized on synaptic differentiations, suggesting that 5-HT may act synaptically on the 5-HT7 receptor. This localization is compared with other 5-HT receptor localizations, and their physiological consequences are discussed.