Urothelium releases neuro-like chemical substances for micturition reflex

以往的研究表明，尿路上皮细胞α_1肾上腺素能受体的激活可释放神经递质。本研究旨在探讨大鼠膀胱尿路上皮中是否有肾上腺素能受体的表达，以及抑制这些受体是否会影响反射性排尿。实验选用雌性Wistar大鼠。免疫印迹法检测受体的表达。通过膀胱测压、膀胱腔内三磷酸腺苷浓度测定和传入神经记录来研究受体激活的影响。α-1d&gt；拮抗剂萘哌地尔(0.75-1.66 mg/kg)静脉注入颈外静脉。免疫组织化学和免疫组织化学方法检测尿路上皮组织中肾上腺素能受体的表达。1受体拮抗剂NAFP可延长清醒大鼠持续输注膀胱测压时的收缩间期(ICI)，为对照组的143%，并可抑制膀胱内注入0.1%的醋酸对ICI的兴奋作用(220%)。NAFP可抑制膀胱扩张(32.0%)或醋酸注入(30.4%)引起的膀胱传入神经活动，并降低膀胱扩张时膀胱灌流液中的ATP水平(36.6%)。内源性儿茶酚胺似乎作用于尿路上皮中的α_1d和gt；受体，以促进机械敏感型膀胱传入神经的活动和反射性排尿。

Previous studies revealed that activation of alpha_1 adrenergic receptors in urothelial cells releases neurotransmitters. This study was undertaken to determine if alpha_<1D> adrenergic receptors are expressed in the urothelium of the rat bladder and if inhibition of these receptors affects reflex voiding. Female Wistar rats were used for the experiments. Receptor expression was evaluated by Western blot. The effects of receptor activation were studied using cystometrograms, measurement of ATP concentrations in the bladder lumen and afferent nerve recording. The alpha_<1D> antagonist, naftopidil (0.75-1.66 mg/kg) was administered intravenously into the external jugular vein. Expression of alpha_<1D> adrenergic receptors was detected in urothelial tissue with Westernblot and Immunohistochemistry. The alpha_<1D> receptor antagonist, naftopidil prolonged the intercontraction interval (ICI, 143 % of the control) during continuous infusion cystometrograms in conscious rats, and suppressed the excitatory effect of intravesical infusion of acetic acid (0.1 %) on the ICI (220 %). Naftopidil inhibited bladder afferent nerve activity induced by bladder distension (32.0%) or acetic acid infusion (30.4 %) and reduced the ATP levels in the bladder perfusate during bladder distension (36.6 %). Endogenous catecholamines appear to act on alpha_<1D> receptors in the urothelium to facilitate the mechano-sensitive bladder afferent nerve activity and reflex voiding.