Jones S L, Light A R
Department of Pharmacology, College of Medicine, University of Oklahoma, Oklahoma City 73190.
J Comp Neurol. 1990 Jul 8;297(2):267-82. doi: 10.1002/cne.902970209.
Electrical and chemical stimulation given in the ventral medullary raphe nuclei inhibits spinal nociceptive reflexes and spinal nociceptive transmission; serotoninergic receptors have been demonstrated to partially mediate that inhibition. In the present study, the termination patterns of raphespinal fibers in the rat lumbar spinal cord demonstrating serotonin-like immunoreactivity were examined by using the anterograde tracer Phaseolus vulgaris leucoagglutinin (PHA-L) in combination with immunohistochemistry. Fibers and terminations from the ventral medullary raphe nuclei (raphe magnus and raphe pallidus) demonstrating both PHA-L- and serotonin-like immunoreactivity were identified in all laminae of the dorsal horn and the ventral horn. Networks of large fibers, characterized by large boutons, and which did not demonstrate serotonin-like immunoreactivity, were identified in deeper laminae of the dorsal horn. The heterogeneous morphology of raphespinal fibers identified in the dorsal horn suggests that these fibers also may be heterogeneous in neurochemistry and function. Medial medullary sites outside the raphe nuclei were found to innervate the ventral horn and all laminae of the dorsal horn, with the exception of lamina I. Descending fibers and terminations also demonstrating serotonin-like immunoreactivity were identified in deep laminae (III, IV, V, VI) of the dorsal horn and in the ventral horn. Similarly, large fiber networks were identified which did not demonstrate serotonin-like immunoreactivity.
延髓腹侧中缝核给予的电刺激和化学刺激可抑制脊髓伤害性反射和脊髓伤害性传递；已证实5-羟色胺能受体部分介导这种抑制作用。在本研究中，通过使用顺行示踪剂菜豆白细胞凝集素（PHA-L）结合免疫组织化学方法，研究了大鼠腰段脊髓中显示5-羟色胺样免疫反应性的中缝脊髓纤维的终末模式。在背角和腹角的所有层中均鉴定出了来自延髓腹侧中缝核（中缝大核和中缝苍白核）的同时显示PHA-L和5-羟色胺样免疫反应性的纤维和终末。在背角较深层中鉴定出了以大终扣为特征且不显示5-羟色胺样免疫反应性的大纤维网络。在背角中鉴定出的中缝脊髓纤维的异质性形态表明，这些纤维在神经化学和功能上也可能是异质的。发现中缝核以外的延髓内侧部位支配腹角和背角的所有层，但I层除外。在背角深层（III、IV、V、VI层）和腹角中也鉴定出了同时显示5-羟色胺样免疫反应性的下行纤维和终末。同样，也鉴定出了不显示5-羟色胺样免疫反应性的大纤维网络。
