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新近发现的Ⅰ型(VGLUT1)和Ⅱ型(VGLUT2)囊泡膜谷氨酸转运体已被作为谷氨酸能神经终末的标识物,在中枢神经系统呈互补分布,显示二者可能存在功能差异。以往的研究也已经证实接受口面部浅感觉信息的三叉神经脊束核,特别是尾侧亚核(Vc)向外侧臂旁核(LPB)发出丰富的谷氨酸能投射纤维,但该投射纤维内究竟是哪一型的囊泡膜谷氨酸转运体承担谷氨酸的转运功能,到目前为止尚未见报道。本实验选用SD大鼠,综合运用顺行束路追踪[将霍乱毒素B亚单位-CTb分别注入一侧Vc、三叉神经脊束核极间亚核(Vi)、吻侧亚核(Vo)]和免疫荧光组织化学相结合的三重标记技术,在激光共聚焦显微镜下对Vc、Vi和Vo内向LPB投射纤维内所含的囊泡膜谷氨酸转运体(VGLUTs)的情况进行了研究。结果显示:(1)将CTb分别注入大鼠一侧Vc、Vi或Vo后,在同侧的LPB内可观察到许多CTb顺行标记纤维,其中以来自Vc的标记纤维最多,Vi次之,Vo最少;(2)在LPB内可见部分CTb顺标终末同时表达VGLUT2样免疫阳性,但未见与VGLUT1样阳性终末的共存;(3)可观察到部分CTb/VGLUT2双标终末散在分布于NeuN标记的神经元的胞体周围,并与之形成密切接触。以上结果提示:大鼠口面部浅感觉、特别是伤害性信息从三叉神经脊束核向LPB传递的过程中,谷氨酸发挥着重要作用,负责其内谷氨酸转运功能的主要是VGLUT2。
The newly discovered vesicular glutamate transporters of type V (VGLUT1) and type II (VGLUT2) have been identified as markers of glutamatergic terminals in the central nervous system, indicating that they may function difference. Previous studies have also demonstrated that the trigeminal nucleus of the trigeminal nucleus, particularly the caudal subnucleus (Vc), which receives superficial sensory information of the oral area, emits abundant glutamate-formable fibers toward the lateral parabrachial nucleus (LPB) Which type of vesicular glutamate transporter within the glutamate transport function, so far has not been reported. In this experiment, SD rats were selected and traced using the following method [tracing the cholera toxin B subunit-CTb into one side of Vc, Vi of the trigeminal nerve bundle, and sub-nucleus of the kissel of the trigeminal nerve) And triplex labeling technique combined with immunofluorescence histochemistry were used to investigate the vesicular glutamate transporter (VGLUTs) contained in the fibers by Vc, Vi and Vo inward LPB projection under laser confocal microscope. The results showed that: (1) CTb were injected into the rat side of the Vc, Vi or Vo, in the same side of the LPB can be observed in a number of CTb cis-labeled fibers, of which from Vc labeled fiber most, Vi times, Vo was the least; (2) In the LPB, we can see that CTB / VGLUT2-like immunopositive cells were also expressed in the end of CTb, but no coexistence with VGLUT1-like positive terminals. (3) Distributed around and in close contact with NeuN-labeled neurons. The above results suggest that glutamate plays an important role in the light sensation, especially nociceptive information, of the rat oral and parietal area from the trigeminal nucleus to the LPB, and is mainly responsible for the glutamate transport function of VGLUT2.