Feng Yu-Peng, Li Yun-Qing, Wang Wen, Wu Sheng-Xi, Chen Tao, Shigemoto Ryuichi, Mizuno Noboru
Department of Anatomy and K. K. Leung Brain Research Centre, The Fourth Military Medical University, Xi'an 710032, PR China.
Neurosci Lett. 2005 Nov 18;388(3):144-8. doi: 10.1016/j.neulet.2005.06.068.
Previous studies have shown that neurons in the sacral dorsal commissural nucleus (SDCN) express neurokinin-1 receptor (NK1R) and can be modulated by the co-release of GABA and glycine (Gly) from single presynaptic terminal. These results raise the possibility that GABA/Gly-cocontaining terminals might make synaptic contacts with NK1R-expressing neurons in the SDCN. In order to provide morphological evidence for this hypothesis, the triple-immunohistochemical studies were performed in the SDCN. Triple-immunofluorescence histochemical study showed that some axon terminals in close association with NK1R-immunopositive (NK1R-ip) neurons in the SDCN were immunopositive for both glutamic acid decarboxylase (GAD) and glycine transporter 2 (GlyT2). In electron microscopic dual- and triple-immunohistochemistry for GAD/GlyT2, GAD/NK1R, GlyT2/NK1R, or GAD/GlyT2/NK1R also revealed dually labeled (GAD/GlyT2-ip) synaptic terminals upon SDCN neurons, as well as GAD- and/or GlyT2-ip axon terminals in synaptic contact with NK1R-ip SDCN neurons. These results suggested that some synaptic terminals upon NK1R-expressing SDCN neurons co-released both GABA and Gly.
以往的研究表明，骶髓后连合核（SDCN）中的神经元表达神经激肽-1受体（NK1R），并且可受到来自单个突触前终末的γ-氨基丁酸（GABA）和甘氨酸（Gly）共同释放的调节。这些结果提示，含有GABA/Gly的终末可能与SDCN中表达NK1R的神经元形成突触联系。为了给这一假说提供形态学证据，在SDCN中进行了三重免疫组织化学研究。三重免疫荧光组织化学研究显示，SDCN中与NK1R免疫阳性（NK1R-ip）神经元紧密相连的一些轴突终末对谷氨酸脱羧酶（GAD）和甘氨酸转运体2（GlyT2）均呈免疫阳性。在针对GAD/GlyT2、GAD/NK1R、GlyT2/NK1R或GAD/GlyT2/NK1R的电子显微镜双重和三重免疫组织化学研究中，也揭示了SDCN神经元上双重标记（GAD/GlyT2-ip）的突触终末，以及与NK1R-ip SDCN神经元形成突触联系的GAD和/或GlyT2-ip轴突终末。这些结果表明，表达NK1R的SDCN神经元上的一些突触终末共同释放GABA和Gly。
