单侧坐骨神经完全结扎对大鼠腰段背根神经节内VGluT1阳性神经元的影响

本实验将大鼠分为两组(正常对照组和单侧坐骨神经完全结扎组),采用免疫细胞化学和中性红复染的方法分别观察了正常大鼠和单侧坐骨神经完全结扎后存活不同时间组大鼠腰4(L4)节段的背根神经节(DRG)内I型囊泡膜谷氨酸转运体(VGluT1)样阳性神经元的分布及其数量的变化。结果如下:(1)正常大鼠L4节段的DRG内可观察到VGluT1样阳性产物呈点状或斑状分布于胞浆内,有大约71.5%的DRG细胞表达VGluT1样免疫阳性,其中以大型(>40μm)和中等大小(20~40μm)的神经元为主(分别占整个VGluT1样阳性细胞总数的30.7%和65.9%);(2)坐骨神经结扎后第1、2d,在结扎同侧L4节段的DRG内未检测到VGluT1样阳性神经元数量的明显变化;但自术后第4d开始,VGluT1样阳性神经元的数量随术后存活时间的延长逐渐减少。结扎1~4周大鼠DRG内VGluT1样阳性神经元数量在同一个动物的手术侧与对照侧相比有明显减少(P<0.01);而结扎1~4周大鼠的手术侧DRG内VGluT1样阳性神经元的数量也明显低于结扎1~3d大鼠的手术侧(P<0.05或P<0.01)。以上结果表明,DRG内合成VGluT1样阳性物质的神经元主要是大、中型细胞,DRG细胞可通过轴浆流将VGLluT1向周围突运输,故外周神经的损伤很易影响到DRG神经元内VGluT1的合成。

EFFECTS OF VGLUT1-POSITIVE NEURONS IN THE LUMBAR SEGMENT OF DORSAL ROOT GANGLION AFTER THE COMPLETE LIGATION OF UNILATERAL SCIATIC NERVE OF THE RAT

The rats were divided into 2 groups in the present study (normal group and operated group). Immunocytochemical and eosin counterstaining methods were used to examine the distribution and change of the number of vesicular glutamate transporter 1 (VGluT1)-like immunoreactive neurons in the fourth lumbar (L4) segment of dossal root ganglion (DRG) neurons in the normal rat and the complete ligation of sciatic nerve (SN) of the rat with different survival time. The results were as follows: (1) VGluT1-immunoreactivity (VGluT1-LI) was seen as punctuated immunostaining in the L4 segment of DRG neurons of the normal rats. About 71.5% of DRG neurons showed VGluT1-LI. In these VGluT1-positive neurons, the large-diameter (>40 μm) and medium-diameter neurons (20～40 μm) were about 30.7% and 65.9% in the total VGluT1-immunoreactive neurons; (2) No obvious change was detected in the number of VGluT1-positive neurons in L4 DRG after 1, 2 days of complete SN ligation. But from 4 days after complete SN ligation, the number of VGluT1-positive neurons decreased gradually according to the survival time. From 1 to 4 weeks after complete SN ligation, the number of VGluT1-positive neurons decreased significantly than that of the control side in the same rat (P<0.01). On the other hand, the number of VGluT1-positive neurons ipsilateral to the ligation side on 1 to 4 weeks was significantly lower than on 1 to 3 days (P<0.05 or P<0.01). The results suggest that VGluT1 is mainly synthesized in the large- and medium-diameter neurons of DRG and transported peripherally through centrifugal axonal flow in peripheral axons of DRG neurons. Therefore, VGluT1 synthesis in the DRG is vulnerable to the damage of the peripheral axons.