Hall S R, Wang L, Milne B, Loomis C
Department of Anaesthesia, Queens University, Kingston, Ontario, Canada.
Anesth Analg. 1999 May;88(5):1125-30. doi: 10.1097/00000539-199905000-00030.
After the administration of intrathecal strychnine, allodynia is manifested as activation of supraspinal sites involved in pain processing and enhancement of cardiovascular responses evoked by normally innocuous stimuli. The objective of this study was to investigate the effect of strychnine-induced allodynia on adrenergic neuronal activity in the C1 area of the rostral ventrolateral medulla (RVLM), a major site involved in cardiovascular regulation. The effect of intrathecal strychnine (40 microg) or saline followed by repeated hair deflection to caudal lumbar dermatomes in the urethane-anesthetized rat was assessed by measuring voltammetric changes in the RVLM catechol oxidation current (CA x OC), mean arterial pressure (MAP), and heart rate (HR). After the administration of intrathecal strychnine, hair deflection evoked a significant and sustained increase in the RVLM CA x OC and MAP (peak 146.4%+/-5.6% and 159%+/-18.4% of baseline, respectively; P < 0.05). There was a nonsignificant increase in HR (peak 128%+/-8.2%). In the absence of hair deflection, there was no demonstrable change. Intrathecal saline-treated rats failed to demonstrate changes in RVLM CA x OC, MAP, or HR. In the present study, we demonstrated that, after the administration of intrathecal strychnine, innocuous hair deflection evokes temporally related neuronal activation in the rat RVLM and an increase in MAP. This suggests that the RVLM mediates, at least in part, the cardiovascular responses during strychnine allodynia.
Neural injury-associated pain, as manifested by allodynia, is resistant to conventional treatment. In a rat model of allodynia, we demonstrated activation of the brain region involved in sympathetic control. Innovative therapies that target this region may be successful in managing this debilitating condition.
鞘内注射士的宁后，痛觉过敏表现为参与疼痛处理的脊髓上部位的激活以及由通常无害刺激诱发的心血管反应增强。本研究的目的是调查士的宁诱导的痛觉过敏对延髓头端腹外侧区（RVLM）C1区肾上腺素能神经元活动的影响，RVLM是参与心血管调节的主要部位。通过测量RVLM儿茶酚氧化电流（CA×OC）、平均动脉压（MAP）和心率（HR）的伏安变化，评估在乌拉坦麻醉的大鼠中鞘内注射士的宁（40微克）或生理盐水后，对尾侧腰段皮节进行反复毛发轻拂的效果。鞘内注射士的宁后，毛发轻拂引起RVLM的CA×OC和MAP显著且持续增加（峰值分别为基线的146.4%±5.6%和159%±18.4%；P<0.05）。HR有不显著的增加（峰值为128%±8.2%）。在没有毛发轻拂的情况下，没有可证明的变化。鞘内注射生理盐水的大鼠未表现出RVLM的CA×OC、MAP或HR的变化。在本研究中，我们证明，鞘内注射士的宁后，无害的毛发轻拂在大鼠RVLM中引起时间相关的神经元激活和MAP增加。这表明RVLM至少部分介导了士的宁痛觉过敏期间的心血管反应。
由痛觉过敏表现出的神经损伤相关疼痛对传统治疗有抗性。在痛觉过敏的大鼠模型中，我们证明了参与交感神经控制的脑区被激活。针对该区域的创新疗法可能成功治疗这种使人衰弱的病症。
