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目的观察大鼠三叉神经本体觉中枢通路上第三级核团内Parvalbumin样阳性轴突终末与丘脑投射神经元之间是否存在突触联系. 方法用HRP逆行追踪和包埋前免疫电镜相结合的双重标记法.将WGA-HRP注入丘脑腹后内侧核逆行标记投射神经元. 结果 WGA-HRP注入丘脑腹后内侧核(VPM)后,WGA-HRP标记神经元主要分布在感觉主核背内侧部(Vpdm)、三叉上核尾外侧部(Vsup-CL)以及三叉神经运动核腹侧区(AVM)和上橄榄核背侧区(ADO).电镜下可见PV样阳性神经元的轴突终末与WGA-HRP标记的胞体或者树突形成突触联系.另外PV阴性神经元的轴突终末也与WGA-HRP标记的胞体或树突形成突触联系,这些胞体或树突偶尔为PV阳性. 结论在三叉神经本体感觉信息从第三级神经元向丘脑腹后内侧核(VPM)传递的过程中,PV样阳性神经元可能通过突触传递机制而发挥作用.“,”Objective To examine if axonal varicosities with parvalbumin-like immunoreactivity(PV-LI) might make synaptic connections with thalamic projection neurons in the third-order nuclei of central pathway of trigeminal proprioceptive sensation of the rat. Methods The HRP-retrograde tracing method combined with immuno-electron microscopy was used.Projection neurons were retrogradely labeled with wheat germ agglutinin-horseradish peroxidase(WGA-HRP) which was injected into the ventral posteromedial nucleus(VPM) of the thalamus. Results After injection,a number of WGA-HRP-labeled neurons were observed mainly in the principal sensory trigeminal nucleus(Vp),the caudolateral part of supratrigeminal nucleus (Vsup-CL),the area ventral to the motor trigeminal nucleus(AVM) and the area dorsal to the superior olivary nucleus(ADO).Electron microscopy confirmed that axon terminals with PV-LI made synaptic contact on somatic and dendritic profiles which were labeled with WGA-HRP.In addition,some PV-negative axon terminals made synapses with WGA-HRP-labeled somatic or dendritic profiles occasionally showed PV-LI.Conclusion It was indicated that some of PV-containing projection neurons might be involved in the transmission of the trigeminal proprioceptive information from the third-order nuclei to the VPM of thalamus through the mechanism of synaptic transmission.