人工体神经-内脏神经反射弧控制下大鼠盆底横纹肌运动神经元的定位分布

DISTRIBUTION OF RATS' PELVIC MUSCLES MOTONEURONS INNERVATED BY ARTIFICAL SOMATIC-AUTONOMIC REFLEX ARC

目的研究正常大鼠及建立人工体神经-内脏神经反射弧截瘫后,支配大鼠盆底肌肉运动神经元胞体的分布。方法雄性SD大鼠35只,随机分为正常组(n=10):大鼠不作任何处理;模型组(n=25):大鼠建立人工体神经-内脏神经反射弧截瘫。于造模后6个月,取正常组(n=10)及模型A组(n=20)大鼠行荧光金(fluorogold,FG)注射至尿道外括约肌、坐骨海绵体肌、球海绵体肌及肛门外括约肌,行逆行神经追踪,荧光显微镜观察FG阳性神经细胞。采用麦芽凝集素结合的辣根过氧化物酶(malt agglutinator binding horseradish peroxidase,WGA-HRP)作为顺行神经示踪剂,取模型B组(n=5)大鼠左侧L4前角注入WGA-HRP,经3,3′,5,5′-四甲基联苯胺(3,3′,5,5′-tetramethylbenzidine,TMB)-HRP显色后,光镜下观察大鼠尿道外括约肌、坐骨海绵体肌、球海绵体肌及肛门外括约肌内神经纤维末梢。结果注射FG后,正常组:尿道外括约肌或坐骨海绵体肌标记神经元位于脊髓L5～S1段前角背外侧核;球海绵体肌或肛门外括约肌,标记神经元位于脊髓L5～S1段前角背内侧核;模型A组:尿道外括约肌、坐骨海绵体肌、球海绵体肌及肛门外括约肌,左侧L4前角均可见FG标记神经元。模型B组:大鼠左侧L4前角注入WGA-HRP后,尿道外括约肌、坐骨海绵体肌、球海绵体肌及肛门外括约肌内可见大量神经纤维末梢着色。结论正常大鼠盆底横纹肌运动神经元主要位于L6前角,人工体神经-内脏神经反射弧下盆底横纹肌运动神经元主要分布于L4前角;脊髓L4前根与L6前根吻合后形成的“异类神经纤维”发出运动神经纤维支配尿道外括约肌、坐骨海绵体肌、球海绵体肌及肛门外括约肌。

Objective To investigate the distribution of rats＇ pelvic muscles motoneurons innervated by artifical somatic-autonomic reflex arc. Methods Thirty-five SD rats were randomly divided into normal group （n=10） and mode[ group （n=25）. The rats in the normal group were given no treatment. In the normal group, the artifica[ somatic-autonomic reflex arc was established. Six months after establishing the model, external urethral sphincter （EUS）, ischiocavernosus （IC）, bulbocavernosus （BS） and external anal sphincter （EAS） of the rats in normal group （n 10） and of the rats in model group A （n--20） were injected with fluorogold （FG）. The reversal neural tracing was done. FG positive neural cells were observed by fluorescent microscope. Malt agglutinator binding horseradish peroxidase （WGA-HRP） was injected into L4 spinal cord of the rats in model group B （n=5） as the anterograde tracer. After being treated with TMB-HRP reaction, the axon endings in the neuromuscular junction in pelvic striated muscles （EUS, IC, BS, EAS） were investigated with light microscopes. Results In normal group, EUS and IC injections resulted in transport of FG to neur~）ns in the dorsolateral nucleus （DL） of the ventral horn of the L5-S1, and BS and EAS in the dorsomedial nucleus （DM） of ventral horn in the L5-S1. In the model group A, EUS, IC, BS and EAS injections resulted in transport of FG to neurons in the left ventral horn in the 1.4. In model group B, after WGA-HRP was injected into the L4 left ventral horn, HRP positive axon terminals were observed in the EUS, IC, BS and EAS. Conclusion In the normal rats, the pelvic striated muscles motoneurons locate in the ventral horn of L5-S1. In the model rats, the pelvic striated muscles motoneurons innervated by artificial somatic-autonomic reflex arc locate in the ventral horn of the L1. After the artificial somatic-autonomic reflex arc is established, the isomerous nerve fiber innervates EUS, IC, BS and EAS.