蛋白激酶C在甲醛复制内脏炎症痛大鼠脊髓背角神经元电活动中的作用

Effect of protein kinase C on the electric activity of spinal dorsal horn neurons in rats with visceral inflammatory pain induced by formalin

目的:观察蛋白激酶C抑制剂氯丙嗪对甲醛复制的内脏炎症痛大鼠脊髓背角神经元电活动的影响,了解蛋白激酶C在甲醛复制的内脏炎症痛中的作用。方法:实验于2005-01/11在泰山医学院基础医学研究所完成。选用24只健康成年Wistar大鼠,数字表法随机分为3组(n=8):①甲醛组:体积分数为0.05的甲醛100μL直肠黏膜下注射致炎,复制内脏炎症痛模型。②甲醛+生理盐水组:在脊髓背角找到对直肠刺激敏感的神经元后,腹腔注射生理盐水0.4mL/kg,30min后记录前对照反应,然后行甲醛直肠黏膜下致炎,方法和剂量同甲醛组。③甲醛+氯丙嗪组:腹腔注射25g/L氯丙嗪0.4mL/kg,其余处理同甲醛+生理盐水组。记录3组大鼠注射甲醛后120min内脊髓背角神经元放电频率的变化,以15min为一个时间段,共记录8个时间段。以给药前神经元的放电频率为参照,计算给药后反应的相对值(给药后实际反应频率/给药前实际反应频率×100%)。结果:24只大鼠全部进入结果分析,共记录到24个单位的反应结果。①甲醛组在给药后0～15min和16～30min时间段的放电频率分别为致炎前基线水平的(283.7±46.0)%和(254.0±37.4)%,与致炎前相比均有显著性增加(P<0.05)。②甲醛+氯丙嗪组在致炎后0～15min和16～30min两时间段的脊髓背角神经元放电频率分别为基线水平的(124.6±10.25)%和(105.4±8.69)%;甲醛+生理盐水组致炎后同时间段的放电频率为基线水平的(279.7±37.4)%和(249.2±38.5)%。甲醛+氯丙嗪组在致炎后0～15min和16～30min两时间段的放电频率低于其他2组(P<0.05),另2组比较差异不显著(P>0.05)。结论:①甲醛直肠黏膜下注射可稳定复制大鼠炎症性内脏痛模型。②蛋白激酶C抑制剂氯丙嗪可使脊髓背角神经元放电频率减少,提示蛋白激酶C参与甲醛诱导急性炎症引起的痛觉敏感化的形成。

AIM： To explore the effect of chlorpromazine （CP）, the inhibitor of protein kinase C （PKC）, on the electric activity of spinal cord dorsal horn neurons evoked by formalin, and understand the effects of PKC on visceral inflammatory pain evoked by formalin. METHODS：The experiment was conducted in the Department of Basic Medical Sciences, Taishan Medical College from January to November 2005. Twenty-four adult healthy Wistar rats were selected and randomly divided into 3 groups with 8 rats in each group：①formalin group （F group）： Rats were made into models of visceral inflammatory pain by injection of 5% formalin （100μL） under the mucosa of intestine.②Formalin ＋ normal saline （F＋NS） group： Rats were intraperitoneally injected with normal saline （0.4 mL/kg） after neurons sensitive to the stimulus of intestine were found on the spinal dorsal horn, and the responses were recorded at 30 minutes later. The inflammation was induced by formalin in the mucosa of intestine with the same method and dose as the F group. ③Formalin ＋ chlorpromazine （F＋CP） group： rats were intraperitoneally injected with 25 g/L CP （0.4 mL/kg）, and the rests were the same as those in the F＋NS group. Changes of discharge frequency of spinal dorsal horn neurons within 120 minutes Mter injection of formalin were recorded in three groups at each 15 minutes for totally 8 times. The discharge frequen- cy of neurons before administration was taken as the reference, and the relative magnitude of response after administration was calculated （response frequency after administration/response frequency before administrationx 100%）. RESULTS：A total of 24 rats were involved in the analysis of results, and the responses of 24 units were recorded. ①The discharge frequency of F group in 0-15 minutes and 16-30 minutes after administration were （283.7±46.0）% and （254.0±37.4）% of the baseline level respectively, which were significantly increased compared with those before inflanunation-induction （P 〈 0.05）.②The discharge frequency of F＋CP group in 0-15 minutes and 16-30 minutes were （124.6±10.25）% and （105.4%±8.69）% respectively of the baseline level after formalin injection. The discharge frequency of F＋NS group in 0-15 minutes and 16-30 minutes were （279.7±37.4）% and （249.2±38.5）% respectively of the baseline level respectively after formalin injection. The discharge frequency in 0-15 minutes and 16-30 minutes after formalin injection were lower in the F＋CP group than the other two groups （P 〈 0.05）, while there were no significant differences between the other two groups （P 〈 0.05）. CONCLUSION： ①Rat model of visceral inflammatory pain can be stabilized by injection of formalin under the mucosa of intestin.②CP, the inhibitor of PKC, can reduce the discharge frequency of spinal cord dorsal horn neurons, which suggests that PKC is involved in the formation of hyperalgesia induced by acute inflammation.