Department of Autonomic Neuroscience, Tokyo Metropolitan Institute of Gerontology, Itabashi-ku, Japan.
Auton Neurosci. 2012 Apr 3;167(1-2):12-20. doi: 10.1016/j.autneu.2011.11.002. Epub 2011 Dec 11.
Effects of gentle skin stimulation of various segmental areas on the micturition contractions of the urinary bladder were examined in anesthetized male rats. The bladder was expanded by infusing saline via urethral cannula until the bladder produced rhythmic micturition contractions as a consequence of rhythmic burst discharges of vesical pelvic efferent nerves. Gentle stimulation was applied for 1 min by slowly rolling on top of skin with an elastomer "roller". Rolling on the perineal area inhibited both micturition contractions and pelvic efferent discharges during and after stimulation. Stimulation of the hindlimb, abdomen and forelimb inhibited micturition contractions after stimulation ended, in this order of effectiveness. During stimulation of the perineal skin, the reflex increase in pelvic efferent discharges in response to bladder distension to a constant pressure was also inhibited up to 45% of its control response. The inhibition of the micturition contractions induced by perineal stimulation was abolished, to a large extent by the opioid receptor antagonist naloxone and completely by severing cutaneous nerves innervating the perineal skin. We recorded unitary afferent activity from cutaneous branches of the pudendal nerve and found that the fibers excited by stimulation were low-threshold mechanoreceptive Aβ, Aδ and C fibers. Discharge rates of afferent C fibers (7.9 Hz) were significantly higher than those of Aβ (2.2 Hz) and Aδ (2.9 Hz) afferents. The results suggest that low frequency excitation of low threshold cutaneous mechanoreceptive myelinated and unmyelinated fibers inhibits a vesico-pelvic parasympathetic reflex, mainly via release of opioids, leading to inhibition of micturition contraction.
我们在麻醉雄性大鼠中检查了对各个节段区域的温和皮肤刺激对膀胱排尿收缩的影响。通过尿道套管向膀胱中注入生理盐水使膀胱扩张，直到膀胱由于逼尿肌盆神经传出纤维的节律性爆发放电而产生节律性排尿收缩。通过用弹性体“滚轮”缓慢滚动在皮肤上来施加温和刺激 1 分钟。在刺激过程中和刺激结束后，刺激会阴部会抑制排尿收缩和盆神经传出放电。刺激后肢、腹部和前肢依次抑制排尿收缩。在刺激会阴部皮肤期间，对膀胱扩张至恒定压力引起的盆神经传出放电的反射性增加也被抑制了，其抑制程度高达对照反应的 45%。阿片受体拮抗剂纳洛酮在很大程度上消除了会阴部刺激引起的排尿收缩抑制，而完全切断支配会阴部皮肤的皮神经则完全消除了这种抑制。我们记录了阴部神经皮支的单位传入活动，发现刺激所兴奋的纤维是低阈值机械感受性 Aβ、Aδ 和 C 纤维。传入 C 纤维（7.9 Hz）的放电率明显高于 Aβ（2.2 Hz）和 Aδ（2.9 Hz）传入纤维。结果表明，低阈值皮肤机械感受性有髓和无髓纤维的低频兴奋通过释放阿片样物质抑制逼尿肌-盆神经副交感反射，从而抑制排尿收缩。
