大鼠腰骶髓后连合核SP受体免疫阳性神经元与SP免疫阳性终末的突触联系

应用免疫组织化学双重反应的方法研究了大鼠腰骶髓后连合核内ＳＰ受体免疫阳性神经元在光、电镜下的特征及其与ＳＰ免疫阳性终末的突触联系。结果证明，ＳＰ免疫阳性终末和ＳＰ受体阳性胞体及树突均密集分布于后连合核区。在光镜下双重免疫反应阳性结果显示二者重叠分布，且可见大量的ＳＰ样免疫阳性终扣与ＳＰ受体阳性胞体或树突紧密接触。电镜下证明ＳＰ受体免疫阳性产物不仅位于突触后部位而且分布于胞体和树突的非突触部位，有４２％的ＳＰ受体阳性树突与ＳＰ阳性终末形成突触连接。在此未发现ＳＰ受体免疫阳性终末。通过一系列实验证明：腰骶髓后连合核神经元接受由ＳＰ介导的外周伤害性信息的传入，且其主要为盆腔脏器内脏初级传入成分。

SYNAPTIC CONNECTIONS BETWEEN SUBSTANCE P RECEPTOR POSITIVE NEURONS AND SP-ERGIC TERMINALS IN DORSAL COMMISSURAL NUCLEUS OF RAT LUMBOSACRAL SPINAL CORD

Our previous studies have confirmed that the dorsal commissural nucleus of lumbosacral spinal cord(DCN) receive both somatic and visceral afferent inputs,and contain many axons showing substance p-like immunoreactivity(SP-LI)and many neurons showing SP receptor(SPR)-LI.In order to determine whether SP-LI terminals form synaptic connections wiht SPR-LI neurons,we examined the ultrastructural features of SPR-LI neurons and their relationships with the SP-ergic terminals in the DCN of the rat,by using double-immunohistochemical staining for SPR and SP.Under light microscope,both SP-LI terminals and SPR-LI perikarya and dendrites were seen densely in DCN,and some SP-LI terminals were located in close proximity to SPR-LI perikarya and dendrites. Under electron microscope,The SPR-LI products in DCN neurons were seen not only in postsynaptic sites, but also in non-synaptic regions of perikaryal and dendritic profiles.No axonal profiles contained SPR-LI products.About 42% SPR-LI dendrites were synaptically contacted with SP-ergic terminals.These results indicated that the DCN neurons receive nociceptive signals transmitted through SP, and DCN is a centre which receive nociceptive information mainly from pelvic viscera.