利用腹壁反射重建人工膀胱反射弧的实验研究

An experimental study on the artificial bladder reflex arc established by abdominal wall pathway reflex

目的 研究利用腹壁反射建立“腹壁反射 脊髓中枢 膀胱”神经传导通路 ,探讨躯体运动神经纤维长入副交感神经纤维后支配膀胱平滑肌产生控制性排尿的作用机制。方法 建立SD大鼠右侧“腹壁反射 脊髓中枢 膀胱”人工膀胱反射弧 ,以左侧为对照侧。通过刺激右侧下腹壁反射激发截瘫动物排尿。神经缝合术后 8个月 :①在破坏L5～S4脊髓节段前后 ,观察神经电生理 ,进行膀胱测压 ;②采用辣根过氧化物酶 (HRP)逆行追踪标记技术 ,观察大鼠T11～L1及L4～S4节段脊髓冰冻切片内HRP标记细胞的形态及分布情况。结果 ①在破坏L5～S4脊髓节段造成截瘫前后 ,单相方波 (3mA ,0 .3ms)刺激实验侧T13 后根 ,可记录到实验侧动作电位、膀胱平滑肌复合肌肉动作电位及膀胱平均内压 ,其形态及波幅与对照侧相似。②实验侧T13 脊髓前角及双侧L6～S4节段脊髓中间带外侧核区有HRP标记阳性细胞 ,而对照侧T13 脊髓前角未发现HRP标记细胞。结论 体神经的运动传出支经自体神经移植 ,其轴突能再生长入膀胱平滑肌内副交感神经节细胞 ,并具有良好的传导运动兴奋的功能 ;利用截瘫平面以上的体反射 ,通过硬膜囊内神经根自体神经移植缝合的方法 ,可建立新的人工膀胱反射弧 。

Objective To establish an artificial bladder reflex arc in SD rats by abdominal pathway reflex above the level of spinal cord injury to reinnervate the neuropathic bladder and restore bladder function. It involves a lower abdominal reflex pathway with a modified efferent branch carring the motor impulses to the bladder and initiates autonomic bladder detrusor contraction. Methods The outcome was achieved by intradural microanastomosis of the right T 13 ventral root to S 2 ventral root with autogenous nerve grafting, while leaving the right T 13 dorsal root intact. After axonal regeneration, the “abdominal reflex spinal cord center bladder”new artificial bladder reflex pathway was established, and micturition was induced by scratching the right lower abdominal wall of the rats after spinal cord injury. ① Long term function of the reflex arc was observed by nerve electrophysiological experiments and bladder pressure tests at 8 months postoperation.② 5μl of 30% horseradish peroxidase (HRP) solution was injected into either side of the corpus vesicae at 8 months postoperatively. The animals survived for 60 hours and were killed by perfusing through ascending aorta. The T 11 ～L 1 spinal segments and the L 4～S 4 spinal segments were dissected by frozen section method, and treated with TMB method. The figure and distribution of HRP labeled cells in sections were observed under optical microscope.Results ① Single stimuli(3 mA,0.3 ms) of the right T 13 dorsal root resulted in evoked potentials, the bladder pressures and the bladder smooth muscle complex action potential recorded from the right vesical plexus before and after the spinal cord horizontal injury between L 5 and S 4 segmental level in all 12 SD rats. The figure and amplitude of experimental sides were similar to those of the control. ② There were HRP labeled cells in T 13 ventral horn on the experimental sides and in the intermediolateral nucleus on either side of the L 6～S 4 segments after HRP injection. There wasn’t any HRP labeled cell in T 13 ventral horn on the control sides.Conclusion The somatic motor axons can regenerate through a segment of autogenous nerve into the parasympathetic endoneurial tubes of autonomic nerve. Using the survived somatic reflex above the level of spinal cord injury to reconstruct the bladder autonomic reflex arc by intradural microanastomosis of ventral root with a segment of autogenous nerve grafting is practical in the SD rat model and may have a prospect of clinical application.