大鼠纹状体parvalbumin阳性中间神经元的超微结构

目的:研究纹状体parvalbumin (Parv)阳性中间神经元在神经通路上的突触连接.方法:利用免疫组织化学和神经示踪方法标记SD大鼠纹状体Parv及其相关神经元,光镜和电镜观察阳性神经元的结构和位置关系.结果:Parv阳性中间神经元中等大小,散在分布于纹状体,以背外侧居多.光镜免疫双标记显示Parv阳性中间神经元与皮质、丘脑和中脑黑质的传入轴突终末形成明显的形态位置上的邻近关系,其轴突终末则与纹状体不同类型投射神经元在光镜下也形成邻近关系.Parv阳性中间神经元的免疫电镜观察显示阳性产物主要游离于胞体、树突和轴突的胞质内.Parv阳性中间神经元的胞体和树突均接受大量的非对称型突触传入.Parv阳性轴突终末平均大小为(0.62±0.28)μm,可见其与纹状体神经元的树突、胞体和树突棘形成对称型突触,其中与树突形成的突触占69.64%,与胞体和树突棘形成的突触分别为26.78%和3.58%.结论:纹状体Parv阳性中间神经元形态学上与皮质、丘脑、黑质以及纹状体投射神经元形成突触连接,提示其可能在调节纹状体信息传入和输出过程中具有重要作用.

Ultrastructural observation of striatal parvalbumin interneurons in rat

Objective: To explore the synaptic contact of parvalbumin (Parv) interneurons in neural pathway of striatum corpus. Methods: Immunohistochemical and neural tract-tracing methods were used to label parvalbumin and correlative neurons in rat striatum. The structure and locative relationship of immunolabeled neurons were observed by routine light and electron microscopy. Results: Striatal Parv positive neurons displayed typical interneurons of medium-sized bodies. Parv positive neurons scattered throughout the striatum and were more abundant in the dorsal lateral striatum than that in others. Immunohistochemical double-labeling displayed that Parv positive neurons showed obviously adjacent relationship with afferent terminals and striatal projection neurons. Observation of immunoelectron microscopy(EM) showed that amorphous electron-dense deposited in perikarya of cell bodies, dendrites and axons. EM analysis revealed that Parv positive neurons formed asymmetric synapses with numerous afferent terminals, but their terminals synapsed symmetrically with striatal projection neurons, which mean size of their terminals was (0.82±0.28)μm. The percentage of postsynaptic component for Parv positive terminals was 69.64% (dendrites), 26.79% (cell bodies) and 3.57% (spines), respectively. Conclusion: Morphological characteristics of synapes of Parv positive neurons indicate that they regulate striatal input-output massages.