Zinck Natasha D T, Downie John W
Department of Pharmacology, Faculty of Medicine, Dalhousie University, 5850 College St., Halifax, NS B3H 1X5, Canada.
Prog Brain Res. 2006;152:147-62. doi: 10.1016/S0079-6123(05)52010-7.
Micturition is coordinated at the level of the spinal cord and the brainstem. Spinal cord injury therefore directly interrupts spinal neuronal pathways to the brainstem and results in bladder areflexia. Some time after injury, however, dyssynergic bladder and sphincter function emerges. The changes mediating the appearance of bladder function after spinal cord injury are currently unknown. Primary afferent neurons have been shown to sprout in response to spinal cord injury. Sprouting primary afferents have been linked to the pathophysiology of centrally manifested disorders, such as autonomic dysreflexia and neuropathic pain. It is proposed that sprouting of bladder primary afferents contributes to disordered bladder functioning after spinal cord injury. During development of the central nervous system, the levels of specific neuronal growth-promoting and guidance molecules are high. After spinal cord injury, some of these molecules are upregulated in the bladder and spinal cord, suggesting that axonal outgrowth is occurring. Sprouting in lumbosacral spinal cord is likely not restricted to neurons involved in the micturition reflex. Furthermore, sprouting of some afferents may be contributing to bladder function after injury, whereas sprouting of others might be hindering emergence of function. Thus selective manipulation of sprouting targeting afferents that are contributing to emergence of bladder function after injury is critical. Further research regarding the role that neuronal sprouting plays in the emergence of bladder function may contribute to improved treatment of bladder dyssynergia after spinal cord injury.
排尿在脊髓和脑干水平进行协调。因此，脊髓损伤会直接中断通往脑干的脊髓神经元通路，导致膀胱无反射。然而，在损伤后的一段时间，会出现膀胱和括约肌功能失调。目前尚不清楚脊髓损伤后介导膀胱功能出现变化的机制。已表明初级传入神经元会因脊髓损伤而发生芽生。芽生的初级传入神经已与诸如自主神经反射异常和神经性疼痛等中枢性疾病的病理生理学相关联。有人提出，膀胱初级传入神经的芽生会导致脊髓损伤后膀胱功能紊乱。在中枢神经系统发育过程中，特定的神经元生长促进和导向分子水平很高。脊髓损伤后，其中一些分子在膀胱和脊髓中上调，表明正在发生轴突生长。腰骶脊髓中的芽生可能不限于参与排尿反射的神经元。此外，一些传入神经的芽生可能在损伤后对膀胱功能有贡献，而其他传入神经的芽生可能会阻碍功能的出现。因此，选择性操纵损伤后对膀胱功能出现有贡献的芽生靶向传入神经至关重要。关于神经元芽生在膀胱功能出现中所起作用的进一步研究可能有助于改善脊髓损伤后膀胱功能失调的治疗。
