BACLOFEN REVERSES THE HYPERSENSITIVITY OF DORSAL HORN WIDE DYNAMIC-RANGE NEURONS TO MECHANICAL STIMULATION AFTER TRANSIENT SPINAL-CORD ISCHEMIA - IMPLICATIONS FOR A TONIC GABAERGIC INHIBITORY CONTROL OF MYELINATED FIBER INPUT
BACLOFEN REVERSES THE HYPERSENSITIVITY OF DORSAL HORN WIDE DYNAMIC-RANGE NEURONS TO MECHANICAL STIMULATION AFTER TRANSIENT SPINAL-CORD ISCHEMIA - IMPLICATIONS FOR A TONIC GABAERGIC INHIBITORY CONTROL OF MYELINATED FIBER INPUT
复制标题
DOI：
10.1152/jn.1992.68.2.392
复制
发表时间：
1992-08-01
影响因子：
2.5
通讯作者：
WIESENFELDHALLIN, Z
中科院分区：
文献类型：
--
作者：
HAO, JX;XU, XJ;WIESENFELDHALLIN, Z
1.在配文中，我们描述了短暂性脊髓缺血后大鼠背角宽动态范围(WDR)神经元出现的一种超敏状态。因此，WDR神经元表现出较低的阈值和对低强度机械刺激的反应增强。这些神经元对阈值以上电刺激的反应模式也发生了改变。值得注意的是，对A纤维输入的反应增强了。结论：1.脊髓缺血前后热刺激反应无明显变化。在正常大鼠，记录神经元前1-3小时给予γ-氨基丁酸(GABA)B激动剂巴氯芬(0.1 mg/kg)抑制WDR神经元对高强度机械压力的反应，但不影响阈值和对低强度刺激的反应。在痛觉异常大鼠，类似的巴氯芬预处理完全逆转了WDR神经元对机械刺激的超敏反应，并使神经元对电刺激的反应模式正常化。GABA(A)受体激动剂Muscimol(1 mg/kg ip)对WDR神经元的反应无影响。结果表明，GABA(B)激动剂巴氯芬能有效逆转脊髓短暂性缺血后背角WDR神经元对低强度机械刺激的超敏反应，提示GABA能抑制系统功能障碍可能与神经元超敏反应的发生有关。提示GABA能中间神经元通过巴氯芬敏感的B型GABA受体对来自低阈值机械传入的传入施加紧张性突触前抑制控制，这种控制的中断可能导致对无害刺激(痛觉异常)的痛性反应。
1. In the companion paper, we described a state of hypersensitivity that developed in dorsal horn wide dynamic range (WDR) neurons in rats after transient spinal cord ischemia. Thus the WDR neurons exhibited lower threshold and increased responses to low-intensity mechanical stimuli. The response pattern of these neurons to suprathreshold electrical stimulation was also changed. Notably, the response to A-fiber input was increased. No change in response to thermal stimulation was found before and after spinal cord ischemia.2. In normal rats, the gamma-aminobutyric acid (GABA)B agonist baclofen (0.1 mg/ kg ip) administered 1-3 h before neuronal recording suppressed the responses of WDR neurons to high-intensity mechanical pressure without influencing the threshold and the responses to lower-intensity stimuli.3. In allodynic rats, similar pretreatment with baclofen totally reversed the hypersensitivity of the WDR neurons to mechanical stimuli and normalized the response pattern of neurons to electrical stimulation.4. The GABA(A) receptor agonist muscimol (1 mg/kg ip) did not influence the response of WDR neurons in either normal or allodynic animals.5. The present results demonstrated that the GABA(B) agonist baclofen is effective in reversing the hypersensitivity of dorsal horn WDR neurons to low-intensity mechanical stimulation after transient spinal cord ischemia, indicating that dysfunction of the GABAergic inhibitory system may be responsible for the development of neuronal hypersensitivity.6. It is suggested that GABAergic interneurons exert a tonic presynaptic inhibitory control, through baclofen-sensitive B-type GABA receptors, on input from low-threshold mechanical afferents, and that disruption of this control may result in painful reaction to innocuous stimuli (allodynia).