右美托咪定两种给药方法在急性腹膜炎小鼠局部组织的抗炎镇痛作用中的比较

目的通过观察比较右美托咪定静脉注射和腹腔注射两种给药方法在急性腹膜炎模型小鼠炎性内脏痛的镇痛及抗炎作用。方法 SPF级健康成年雄性小鼠60只,体重24~28 g,采用随机数字表法分为五组,每组12只:空白对照组(CK组)、急性腹膜炎模型组(VP组)、右美托咪定静脉注射组(DEX-V组)、右美托咪定腹腔注射组(DEX-P组)、右美托咪定+甲基牛扁碱组(DEX-M组)。VP组、DEX-V组、DEX-P组DEX-M组腹腔注射0.9%乙酸溶液0.1 ml/10 g建立急性腹膜炎模型,CK组腹腔注射等容量生理盐水。于造模前15 min,VP组、DEX-P组分别经腹腔注射生理盐水、右美托咪定10μg/kg,DEX-V组经尾静脉注射右美托咪定10μg/kg,DEX-M组经腹腔注射右美托咪定10μg/kg和α7nACh受体特异性拮抗剂甲基牛扁碱2.4μg/g。观察并记录小鼠急性腹膜炎模型建立后2 h内的镇静情况、扭体反应和内脏痛指数(VPI评分);建模6 h后取材并采用ELISA法检测小鼠血清和腹膜组织匀浆中IL-6、TNF-α的浓度;取小鼠腹腔注射部位壁层腹膜组织,在光镜下观察其水肿程度和中性粒细胞浸润情况。结果与CK组比较,VP组、DEX-V组、DEX-P组和DEX-M组均出现扭体反应,给药后15、30、45、60、75、90、105、120 min时VPI评分明显升高(P<0.05),血清和腹膜组织匀浆的IL-6和TNF-α浓度均明显升高(P<0.05),腹膜组织出现不同程度水肿及中性粒细胞浸润;与VP组比较,DEX-V组和DEX-P组镇静效果较好,给药后30、45、60、75 min时VPI评分明显降低(P<0.05),血清和腹膜组织匀浆的IL-6和TNF-α浓度均明显降低(P<0.05),腹膜组织水肿减轻、中性粒细胞浸润减少;与DEX-P组比较,DEX-V组腹膜组织匀浆中的IL-6和TNF-α浓度明显升高(P<0.05);DEX-M组镇静情况、给药后45、60、75、90 min时VPI评分、血清和腹膜组织匀浆的IL-6和TNF-α浓度均明显升高(P<0.05),局部腹膜组织水肿明显加重,中性粒细胞浸润增多。结论右美托咪定局部腹腔注射可以有效降低急性腹膜炎小鼠的内脏痛指数,对局部腹膜组织有抗炎作用且效果优于静脉注射,其抗炎机制可能部分与激活a7nACh受体引导的胆碱能抗炎通路有关。

Comparison of anti-inflammatory and analgesic effects of dexmedetomidine in local tissues of mice with acute peritonitis

Objective A possible mechanism of its anti-inflammatory effect was explored by observing the analgesic and anti-inflammatory effects of dexmedetomidine(DEX) intravenous injection and intraperitoneal injection on inflammatory visceral pain in mice with acute peritonitis. Methods Sixty adult male SPF rats, weighing 24-28 g, were divided into 5 groups by using random number table method(n = 12): the blank control group(group CK), the acute peritonitis model group(group VP), the dexmedetomidine intravenous injection group(group DEX-V), the dexmetomidine intraperitoneal injection group(group DEX-P), and the dexmedetomidine+Methylamine group(group DEX-M). Groups VP, group DEX-V, group DEX-P and group DEX-M established an acute peritonitis model by injecting acetic acid solution with density of 0.9%(0.1 ml/10 g) via intraperitoneal injection, whereas, group CK was built up by injecting the same amout of normal saline via abdominal injection. Groups VP, group DEX-P and group DEX-M were abdominal injected with saline, dexmedetomidine 10 μg/kg, dexmedetomidine 10 μg/kg+methylamine 2.4 μg/g 15 min before the establishment of the model, respectively. Group DEX-V was injected through the caudal vein with dextromidine 10 μg/kg. The sedation and visceral pain behavior score(the VPI score) of each group were observed and recorded during the following 2 h after the visceral pain model was established. The rats were harvested and executed 6 h after the model was established, and the expression levels of IL-6 and TNF-α in the serum and peritoneum were obtained by ELISA method. The peritoneal tissue in the abdominal cavity of the mice was selected and the degree of edema and the infiltration of neutrophils were observed undera light microscope. Results Compared with group CK, group VP, group DEX-V and group DEX-P responded with a torsion response, an increasing in VPI score 15, 30, 45, 60, 75, 90, 105, 120 min after administration, serum and peritoneal tissue homogenation of IL-6 and TNF-α(P < 0.05), and an occur of different degrees of edema and neutrophilinfiltration in the peritoneal tissues. Compared with group VP, groups DEX-V and group DEX-P showed a better sedative effect after dexmeidine treatment, and a lower VPI score 30, 45, 60, 75 min after administration, serum and peritoneal tissue homogenate of IL-6 and the level(P < 0.05), as well as a reduce in peritoneal tissue edema and neutrophilinfiltration. Compared with group DEX-P, the concentration of IL-6 and TNF-α in the homogenation of the peritoneal tissue in group DEX-V increased significantly(P < 0.05). The RASS score, VPI score 45, 60, 75, 90 min after administration, serum and peritoneal tissue homogenation of IL-6 and TNF-α also increased in group DEX-M compared with group DEX-P(P < 0.05). And at the same time, obvious increasing in the local peritoneal tissue edema and in neutrophilic infiltration were obtained in group DEX-M. Conclusion The local intraperitoneal injection of dexmedetomidine can effectively reduce inflammatory visceral pain in acute peritonitis mice, and has a better perform on anti-inflammatory effect on local peritoneal tissue than intravenous injection. Its anti-inflammatory mechanism is possibly related to the anti-inflammatory pathway of a7 nACh receptor activator cholinergic.