Spinal 5-HT2 receptor-mediated facilitation of pudendal nerve reflexes in the anaesthetized cat
Spinal 5-HT2 receptor-mediated facilitation of pudendal nerve reflexes in the anaesthetized cat
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DOI：
10.1111/j.1476-5381.1996.tb15378.x
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发表时间：
1996-05-01
影响因子：
7.3
通讯作者：
Thor, KB
中科院分区：
文献类型：
--
作者：
Danuser, H;Thor, KB
5-羟色胺（5-HT）与下尿路的中枢交感神经和躯体控制密切相关。下尿路的交感神经和躯体神经支配分别通过腹下神经和阴部神经的传出轴突传递。2本研究检测了2，5-二甲氧基-4-碘苯基异丙胺（DOI），一种5-HT 2受体亚型选择性激动剂，电刺激传入纤维时，从腹下神经和阴部神经的中央端记录到的诱发电位，骨盆神经和阴部神经采用各种棘化范例来定位作用部位。所有的猫都用外周限制性5-HT 2受体拮抗剂赛脒（xylamidine）（1 mg kg（-1））进行预处理。可靠地产生阴部神经反射的剂量依赖性增加（至对照的228+/-31%）。5-HT 2受体选择性拮抗剂LY 53857（0.3-3 mg/kg，i. v.）可逆转上述升高。另一方面，在脊髓完整的猫，DOI产生的阴部反射没有显着的变化。然而，在DOI预处理的猫脊髓化的几分钟内，观察到阴部反射显著增加（至对照的221+/-16%），这可以被LY 53857逆转。DOI给药后，在急性脊髓或脊髓完整的猫中未观察到对下腹部反射的显著影响。当LY 53857作为初始药物给药时，在脊髓完整或急性脊髓动物中均未观察到任何影响。4这些结果表明脊髓5-HT 2受体的激活促进了阴部反射。在脊髓完整的猫，据推测，DOI激活脊髓上途径介导抑制阴部反射和抵消脊髓5-HT 2受体激活的促进作用。
1 5-Hydroxytryptamine (5-HT) is intimately associated with central sympathetic and somatic control of the lower urinary tract. The sympathetic and somatic innervation of the lower urinary tract is conveyed through efferent axons of the hypogastric and pudendal nerves, respectively.2 The present study examined the effects of 2,5-dimethoxy-4-iodophenylisopropylamine (DOI), a 5-HT2 receptor subtype-selective agonist, on evoked potentials recorded from the central ends of the hypogastric and pudendal nerves in response to electrical stimulation of afferent fibres in the pelvic and pudendal nerves, respectively. Various spinalization paradigms were employed to localize the site of action. All cats were pretreated with xylamidine (1 mg kg(-1)), a peripherally-restricted 5-HT2 receptor antagonist.3 In acute spinal cats, DOI (0.01-3 mg kg(-1), i.v.) reliably produced dose-dependent increases in the pudendal nerve reflex (to 228+/-31% of control). These increases were reversed by the 5-HT2 receptor-selective antagonist, LY53857 (0.3-3 mg kg(-1), i.v.). On the other hand, in spinally-intact cats, DOI produced no significant changes in the pudendal reflex. However, within minutes of spinalization of DOI-pretreated cats, a marked increase (to 221+/-16% of control) in the pudendal reflex was observed which could be reversed by LY53857. No significant effects were observed on hypogastric reflexes in either acute spinal or spinally-intact cats following DOI administration. No effects were seen in either spinally-intact or acute spinal animals when LY53857 was administered as the initial drug.4 These results indicate that activation of spinal 5-HT2 receptors facilitates pudendal reflexes. In spinally-intact cats, it is hypothesized that DOI activates supraspinal pathways that mediate inhibition of the pudendal reflexes and counteracts the facilitatory effects of spinal 5-HT2 receptor activation.