人工反射弧建立后大鼠膀胱胆碱能神经的形态学变化

目的观察体神经一内脏神经人工反射弧建立后,大鼠膀胱肌间神经丛分布的改变以及神经肌肉接头处的变化。方法Sprague—Dawley大鼠随机分为三组：对照组、脊髓横断组和手术重建组。手术重建组大鼠术后饲养3个月,与脊髓横断组大鼠一起进行脊髓横断,再继续饲养3个月,对照组不做任何处理。DiI进行逆行神经追踪;免疫荧光的方法显示DiI阳性标记细胞中的胆碱乙酰转移酶（cholineacetyltransferase,CHAT）;改良的Kamovsky—Roots法检测膀胱铺片中神经纤维的分布。结果DiI阳性标记细胞主要分布于脊髓L3尾部至L5头侧前角,ChAT阳性细胞和DiI阳性标记细胞部分重叠。手术重建组和对照组相比,膀胱肌间神经纤维的数量较少,染色浓度也较浅护〈0．05）;而手术重建组神经纤维密度较脊髓横断组增大,染色浓度增强妒〈0．05）,且出现明显的神经再分布。结论人工体内脏神经反射弧建立后,新的传出支为体神经,可以长入副交感神经纤维,传出神经元的递质仍为乙酰胆碱,膀胱内胆碱能神经纤维再生和乙酰胆碱活性增强且出现神经再分布,这可能在膀胱的控制性排尿中起作用。

Morphological changes of cholinergic nerve fibers in the urinary bladder after establishment of artificial somatic-autonomic reflex arc in rats

OBJECTIVE: To establish an artificial somatic-autonomic reflex arc in rats and observe the following distributive changes of neural fibers in the bladder. METHODS: Adult Sprague-Dawley rats were randomly divided into three groups: control group, spinal cord injury (SCI) group, and reinnervation group. DiI retrograde tracing was used to verify establishment of the model and to investigate the transport function of the regenerated efferent axons in the new reflex arc. Choline acetyltransferase (ChAT) in the DiI-labeled neurons was detected by immunohistochemistry. Distribution of neural fibers in the bladder was observed by acetylcholine esterase staining. RESULTS: DiI-labeled neurons distributed mainly in the left ventral horn from L3 to L5, and some of them were also ChAT-positive. The neural fibers in the bladder detrusor reduced remarkably in the SCI group compared with the control (P < 0.05). After establishment of the somatic-autonomic reflex arc in the reinnervation group, the number of ipsilateral fibers in the bladder increased markedly compared with the SCI group (P < 0.05), though still much less than that in the control (P < 0.05). CONCLUSION: The efferent branches of the somatic nerves may grow and replace the parasympathetic preganglionic axons through axonal regeneration. Acetylcholine is still the major neurotransmitter of the new reflex arc. The controllability of detrusor may be promoted when it is reinnervated by the pelvic ganglia efferent somatic motor fibers from the postganglionic axons.