大鼠脑实质内远位触液神经元中5-HT1A受体的分布及其在神经病理性痛中的表达

本文旨在探讨大鼠脑实质内远位触液神经元中5-HT1A受体的分布及其在神经病理性痛中的作用.慢性结扎损伤坐骨神经建立大鼠神经病理性痛模型,分别以缩足潜伏期(paw withdrawal latency,PWL)和缩足阈值(paw withdrawal threshold,PWT)对大鼠热痛敏和机械触诱发痛反应进行评分,以可靠CB-HRP(cholera toxin subunit B with horseradish peroxidase)法追踪标记脑实质内远位触液神经元,用CB-HRP/5-HT1A受体免疫组织化学双重标记技术定位、鉴别5-HT1A受体在远位触液神经元中的表达,并计数分析5-HT1A受体分布和表达变化与痛行为表现之间的关系.结果表明,在神经病理性痛第1、3、A7、14天,大鼠的PWL分别为19.37±2.74、12.04±1.77、8.74±1.15、12.31±1.94,PWT分别为18.58±3.62、13.05±1.81、6.66±1.43、1 1.55±2.01.CB-HRP标记细胞出现的位置和数量恒定.每只动物CB-HRP/5-HT1A受体双重标记的细胞数量分别为276.14±36.00、161.72±28.41、108.64±6.8l、139.76±44.64,分别占该动物CB-HRP标记细胞总数的95%、60%、40%和55%.与对照组相比,神经病理性痛大鼠PWL、PWT及CB.HRP/5-HT1A受体双标细胞数均有显著性差异(P<0.01).结果提示,大鼠脑实质的特定部位恒定存在远位触液神经元,该类神经元大多含有5-HT1A受体,该受体的表达与神经病理性痛行为表现之间呈负相关关系.

Distribution and effects of 5-HT(1A) receptors in distal cerebral spinal fluid-contacting neurons in rat brain parenchyma in neuropathic pain

The present study aimed to explore the effects of 5-HT(1A) receptors in the distal cerebral spinal fluid-contacting neurons (CSF-CNs) in rat brain parenchyma in neuropathic pain. The model of neuropathic pain with chronic constriction injury (CCI) of the sciatic nerve was made in Sprague-Dawley rats. The behavioral studies of animal were scored and the paw withdrawal latency (PWL) and paw withdrawal threshold (PWT) were measured. The distribution and expression of 5-HT(1A) receptors were observed in the distal CSF-CNs in brain parenchyma with double labeling of cholera toxin subunit B with horseradish peroxidase (CB-HRP) and 5-HT(1A) receptors with immunhistochemistry. The relationship between 5-HT(1A) receptors in distal CSF-CNs and neuropathic pain was analyzed. The results were as follows. On days 1, 3, 7, 14 of neuropathic pain, the PWL was 19.37+/-2.74, 12.04+/-1.77, 8.74+/-1.15 and 12.31+/-1.94, respectively; the PWT was 18.58+/-3.62, 13.05+/-1.81, 6.66+/-1.43 and 11.55+/-2.01, respectively. CB-HRP-labeled neurons of two clusters were always found in definite region but not in other area in brain parenchyma. The number of neurons double-labeled with CB-HRP/5-HT(1A) receptors in each group was 276.14+/-36.00, 161.72+/-28.41, 108.64+/-6.81, and 139.76+/-44.64, which was about 95%, 60%, 40% and 55% of all CB-HRP-labeled neurons in the four courses of neuropathic pain, respectively. It is suggested that the distal CSF-CNs are always located in a special region in rat brain parenchyma and most of them have 5-HT(1A) receptors. A negative correlation is found between the expression of 5-HT(1A) receptors and neuropathic pain.