Role of Spinal GABA Receptors in Neuropathic Pain

描述（由申请人提供）：脊髓中GABA介导的抑制的丧失被认为有助于神经性疼痛的发展和维持。然而，支撑数据令人惊讶地疲软。此外，这些研究没有考虑GABA受体的复杂分子生物学，以及亚基组成和药理学在疾病状态和神经损伤后发生的重复活动条件下如何变化。我们假设神经损伤引起脊髓中GABAA或GABAB受体的表达、分布和亚基组成的即时和长期变化。我们建议在传入疼痛通路的定义的突触前和突触后元件以及表现出神经性疼痛行为时间依赖性变化的良好表征的脊神经结扎模型的背景下来表征这些变化。特别重要的是诱导的变化，在未受伤的，和受伤的初级传入神经元和背角神经元作为神经损伤后的时间函数的这些受体的表达和分子组成。将通过蛋白质印迹测定结扎和假手术大鼠的脊髓背角以及同侧和对侧L4和L5 DRG中GABAA和GABAB受体亚基的表达和亚基组成的变化。将使用双色间接免疫荧光方法和体视学测量来检查GABAA和GABAB受体亚单位在结扎和假手术大鼠的L4和L5 DRG中的化学鉴定的初级传入神经元的不同群体上的分布。免疫组织化学方法还将与结扎和假手术大鼠中脊髓丘脑和脊髓臂旁神经元的逆行标记结合使用，以确定神经损伤后脊髓背角中突触后GABAA和GABAB受体的分布和组成是否也发生改变。分析的时间点范围为受伤后7至140天。这些研究将提供新的信息GABAA和GABAB受体的分布上确定的初级传入神经元和背角神经元的幼稚动物的人口。他们将描述这些受体的分布和分子组成如何随着神经损伤后时间的变化而变化，并为脊髓中神经突触传递的分子和神经解剖学基础提供新的见解。

DESCRIPTION (provided by applicant): Loss of GABA-mediated inhibition in the spinal cord is proposed to contribute to the development and maintenance of neuropathic pain. However, the supporting data are surprisingly weak. Further, these studies have not considered the complex molecular biology of GABA receptors, and how subunit composition and pharmacology change in disease states and under conditions of repetitive activity as occurs after nerve injury. We hypothesize that nerve injury causes immediate, as well as long-term changes in the expression, distribution and subunit composition of GABAA or GABAB receptors in the spinal cord. We propose to characterize these changes in the context of defined presynaptic and postsynaptic elements of the afferent pain pathways and a well-characterized model of spinal nerve ligation that exhibits time-dependent changes in neuropathic pain behaviors. Of particular importance are the changes induced in the expression and molecular composition of these receptors on uninjured, and on injured primary afferent neurons and on dorsal horn neurons as a function of time after nerve injury. Changes in the expression and subunit composition of GABAA and GABAB receptor subunits in the spinal cord dorsal horn, and in ipsilateral and contralateral L4 and L5 DRG of ligated and sham rats will be determined by Western blot. Two-color indirect immunofluorescence methods will be used with stereological measurements to examine the distribution of GABAA and GABAB receptor subunits on different populations of immunohistochemically-identified primary afferent neurons in the L4 and L5 DRG of ligated and sham-operated rats. Immunohistochemical methods will also be used in conjunction with retrograde labeling of spinothalamic and spinoparabrachial neurons in ligated and sham rats to determine whether the distribution and composition of postsynaptic GABAA and GABAB receptors in the spinal cord dorsal horn is also altered after nerve injury. Time points for analysis will range 7 to 140 days after injury. These studies will provide new information about the distribution of GABAA and GABAB receptors on identified populations of primary afferent neurons and dorsal horn neurons in the naive animal. They will describe how the distribution and molecular composition of these receptors changes as a function of time after nerve injury and provide new insights into the molecular and neuroanatomical bases of inhibitorv svnaptic transmission in the spinal cord.