目的观察猫脊髓背根神经节切除后下行纤维5-羟色胺(5-HT)在脊髓背角内的表达变化及5-HT异类终末,探讨其在脊髓背根节切除后的代偿意义。方法 10只成年雄性猫,在腹腔内注射麻醉下行腰1到骶2(L1~S2)单侧背根节切除术,建立猫腰骶背根节全切模型,术后分为急性组5只,存活2周,慢性组5只,存活2个月,实验结束时,动物腹腔内麻醉,开胸并心内灌注固定处理,取腰6(L6)节段脊髓,采用免疫组化染色方法检测手术侧和对侧脊髓背角、Ⅱ板层内5-HT的表达,电镜下观察5-HT异类终末。结果光镜下5-HT阳性染色主要分布于脊髓背角,Ⅱ板层区域较突出,呈细颗粒状和线条状。急性组手术侧与对侧非手术侧阳性染色无明显差异,慢性组两侧阳性染色差异明显,手术侧强于对照侧。电镜下,在慢性组手术侧脊髓Ⅱ板层中,观察到简单终末,发现了5-HT阳性非典型复合终末(ACT),它们较小,外观上呈圆形或椭圆形,多与两个突触后成分形成联系,突触活性带较平直或向外凸,突触内多含均匀清亮小泡或致密核心小泡。结论 5-HT在猫脊髓腰骶背根节切除后主要出现在脊髓背角,Ⅱ板层表达突出,5-HT阳性ACT可能是脊髓背根节全切后的一种下行纤维代偿终末。 Objective To observe the expression of 5-hydroxytryptamine (5-HT) in the dorsal horn of spinal cord and the 5-HT heterogeneous terminal after the dorsal root ganglion (DRG) resection in the cat spinal cord to investigate its compensatory significance after dorsal root ganglion resection. Methods Ten adult male cats underwent lateral lumbosacral vertebra 1-2 (L1 ~ S2) unilateral dorsal root ganglionectomy under intraperitoneal injection anesthesia. Cat lumbosacral dorsal root ganglionectomy models were established and divided into acute group , Survived for 2 weeks, and the chronic group (5) survived for 2 months. At the end of the experiment, the animals were anesthetized by intraperitoneal anesthesia, opened the thoracotomy, and perfused intracardially. The spinal cord of the lumbar segment 6 (L6) was taken and examined by immunohistochemical staining The expression of 5-HT in the dorsal horn of the spinal cord on the contralateral side and contralateral spinal cord, and the 5-HT heterogeneous terminal were observed under electron microscope. Results The positive staining of 5-HT under light microscope mainly distributed in the dorsal horn of spinal cord, and the area of ​​plate layer II was more prominent with fine grainy and lineage. There was no significant difference in the positive staining of the non-surgical side and the contralateral side in the acute group. The positive staining of the two sides in the chronic group was significantly different from the control side. Under electron microscopy, simple terminals were observed in the spinal cord II lamellae of the chronic group, and 5-HT-positive atypical composite terminals (ACTs) were found. They were smaller and appeared round or oval in appearance, with The two postsynaptic components form a link, the synaptic active zone is flatter or convex, and synapses contain more uniform clear or dense core vesicles. CONCLUSIONS: 5-HT mainly appears in the dorsal horn of spinal cord after lumbosacral dorsal root ganglionectomy in cats. The expression of 5-HT positive ACT may be a kind of descending fiber compensatory terminal of the dorsal root ganglion .