利用腹壁反射重建膀胱反射弧的远期功能性研究

目的：利用截瘫平面以上的腹壁反射通路建立SD大鼠的人工膀胱反射弧,以恢复脊髓损伤（SCI）后可控制性膀胱排尿功能。它包含了一个皮肤反射弧（下腹壁反射弧）,并将皮肤反射的运动冲动传入膀胱,引起膀胱的自主性收缩。方法：将SD大鼠右侧T13前根近端与右侧S2前根远端通过一段自体移植神经在硬膜囊内行显微缝合,保持T13后根完整,经一段时间轴突再生后,建立“腹壁反射－脊髓中枢－膀胱”这一新的人工膀胱反射弧。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,在破坏L5－S4脊髓节段前后,分别进行神经电生理、膀胱测压和神经药理学实验等远期功能观察。结果：在破坏L5－S4脊髓节段造成截瘫前后,单相方波（3mA,0.3ms）刺激实验测T13后根,12只SD大鼠的实验侧膀胱神经丛可记录到动作电位,其形态和波幅与对照组相似;串刺激（3mA,20Hz,5s）实验侧T13后根,经新建的膀胱人工反射弧引出膀胱平均内压达对照侧的76％,膀胱平滑肌复合肌肉运作电位平均最大波幅达对照侧81％,波形与对照组相似。在膀胱平滑肌内注射阿托品（0．05mg/kg）或三甲噻酚（5mg/kg）可抑制通过该人工反射弧激发的膀胱平滑肌收缩功能,而膀胱平滑肌肉注射维库溴铵（4mg/kg）对膀胱平滑肌收缩功能无影响。结论：体神经的运动传出支经自体神经移植,其轴突能够再生长入自主神经的副交感神经纤维,并具有良好的传导运动兴奋的功能,新的神经传导通路含有N1和M型受体,冲动传递的神经递质为乙酰胆碱;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,实现截瘫患者可控制性排尿。

Long-term functional study on the artificial bladder reflex arc established by abdominal reflex after spinal cord injury

Objective To establish an artificial bladder reflex arc in SD rats by abdominal reflex pathway above the horizon of spinal cord injury to reinnervate the neuropathic bladder and restore bladder function It involves a skin reflex arc (lower abdominal reflex pathway)with a modified efferent branch that passes the motor impulses to the bladder and initiate autonomic bladder detrusor contraction Methods This 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 Long term function of the reflex arc was observed by nerveelectrophysiological experiments,bladder pressure tests and nervepharmacological experiments at 8 months postoperation Results Single stimuli(3 mA,0 3 ms)of the right T 13 dorsal root resulted in evoked potentials recorded from the right vesical plexus before and after the spinal cord was destroyed horizontally between L 5 and S 4 segmental level in all 12 SD rats The figure and amplitude of the evoked potentials were similar to those of the control Bladder contraction was initiated by trains of stimuli(3 mA,20 Hz,5 s)of the right T 13 dorsal root The bladder pressures increased to average 76% of normal compared to controls and the amplitude of bladder smooth muscle complex action potential increased to average 81% of normal compared to controls These figures were similar to those of the controls Atropine (0 05 mg/kg) or trimethaphan (5 mg/kg) depressed the bladder contractions initiated by the artificial bladder reflex arc and Norcuron( 4 mg/kg) didn't depress the bladder contractions Conclusions The somatic motor axons can regenerate through a segment of autogenous nerve into the parasympathetic endoneurial tubes of autonomic nerve The new pathway is mediated by cholinergic transmission involving both nicotinic(N 1)and muscarinic(M) receptors Using the survived somatic reflex above the horizon 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 potential of clinical application