骶髓5-HT_(2A)受体对于正常大鼠排尿的影响

目的:探讨骶髓控制尿道外括约肌的Onuf's核中是否存在5-HT2A受体,并观察髓腔内给予该受体的拮抗剂酮舍林对于正常大鼠排尿的影响。方法:体重175~200g的SD雌性大鼠14只,随机分为两组:实验组7只,在脊髓L6~S1节段建立脊髓髓腔内置管模型,给予不同浓度的酮舍林(0.01~0.1mg/kg),得到剂量依赖性曲线后再给予5-HT2A受体激动剂DOI(2,5-dimethoxy-4-iodophenyl)-2-aminopropane hydrochloride(0.1mg/kg)。对照组7只,如上述建立脊髓髓腔内置管模型,在脊髓腔内给予生理盐水。3天后在乌拉坦麻醉下,在实验组和对照组大鼠的膀胱内置管连接压力感受器,分别记录实验组和对照组膀胱内压图(CMG)及排尿量、剩余尿量、膀胱容量。待测压结束后,用4%多聚甲醛进行血管灌注取出L6~S1脊髓做冷冻切片并做免疫组化染色,观察并记录5-HT2A受体在脊髓Onuf's核中不同运动神经元的分布情况。结果:对照组大鼠的排尿是节律性的舒缩活动,排尿效率高,高频震荡波(HFOs)的排列整齐并稳定;实验组大鼠在给予酮舍林后,排尿时HFOs的个数呈剂量依赖性减少,同时这种作用可以完全或部分被DOI所逆转,和对照组相比差异有统计学意义,而排尿量、膀胱容量及排尿效率有减少的趋势,但和对照组相比,差异无统计学意义。免疫组化结果显示在大鼠L6脊髓的背后外侧核(RDLN核)、脊髓前角的Ounf's核的背外侧核(DLN)、腹内侧核(VMN)有不同数量的5-HT2A受体免疫反应阳性产物蓄积。结论:骶髓控制大鼠尿道外括约肌舒缩活动的Onuf's核中存在5-HT2A受体,其拮抗剂酮舍林通过与5-HT2A受体特异性结合可以抑制尿道外括约肌的舒缩活动,但由于正常高位中枢的调节作用和受体数量的限制,不会对正常大鼠的排尿功能造成太大影响。

Effects of the 5-HT2A receptor in the sacral cord on controlling micturition in normal rats

Objective：To investigate whether the 5-HT2 Areceptor exists in the Onuf＇s nucleus of the sacral cord,and to examine the effects of the 5-HT2 Areceptor antagonist ketanserin on micturition in normal rats.Method：Fourteen female SD rats with the weight of 175-200 g were used,which were randomly divided into two groups.In experimental group seven of them were inserted intrathecal catheter in the spinal L6-S1 segment,then different concentration of ketanserin（0.01-0.1mg/kg）was given.Dose-response curves for ketanserin were followed by DOI（2,5-dimethoxy-4-iodophenyl）-2-aminopropane hydrochloride（0.1mg/kg）test.In control group seven of them were inserted intrathecal catheter as the experimental group,then different concentration of normal saline was given.Three days later,all rats were anesthetized with urethane.Both two groups were catheterized through the bladder dome for saline-filling cystometry.The cystometrogram,micturition volume,post-void residual volume and bladder capacity were measured.All rats were intravascularly perfused with 4%paraformaldehyde at 1-2hafter the completion of the urodynamic recordings.The L6-S1 spinal cord were removed and pathological sections and immunohistochemical stainings were made.Meanwhile,we observed and recorded the distribution of5-HT2 Areceptor in the spinal motor neuron.Result：Control rats have rhythmic activity with high voiding efficiency and high-frequency oscillations（HFOs）in alignment.Whereas,experimental rats responded to ketanserin with dose-dependent decreasing in the number of HFOs.The effects of ketanserin were partially or completely reversed by DOI,and there was a significant difference compared with the control group.However,micturition volume,post-void residual volume and voiding efficiency tended to decrease,which showed no significant difference.In the L6 segment of the female rats,immunohistochemical staining displayed that the different distribution of 5-HT2 Areceptor immunocytochemical labeling was found in the retrodorsolateral（RDL?