摘要：
Objective To evaluate the effect of dexmedetomidine on visceral pain in rats and the role of α2 adrenergic receptors in locus coeruleus (LC).Methods Thirty-two healthy adult male SpragueDawley rats,weighing 250-300 g,were divided into 4 groups (n=8 each) using a random number table method:control group (group C),visceral pain group (group VP),dexmedetomidine group (group DEX) and α2-adrenergic receptor antagonist atipamezole group (group AP).α2-adrenergic receptor antagonist atipamezole 522 μg/kg was intramuscularly injected in group AP,and the equal volume of normal saline was given instead in C,VP and DEX groups.At 10 min after intramuscular injection,dexmedetomidine 10 μg/kg was injected via the tail vein in DEX and AP groups,and the equal volume of normal saline was given instead in C and VP groups.VP,DEX and AP groups received intraperitoneal injection of 0.9％ acetic acid 10 ml/kg to make the visceral pain model at 15 min after injection via the tail vein.The cumulative visceral pain score was recorded within 60 min after acetic acid injection.The number of c-fos positive cells in LC was detected by immunohistochemistry,and the content of norepinephrine (NA) in the spinal cord were detected by enzyme-linked immunosorbent assay at 2 h after acetic acid injection.Results Compared with group C,the cumulative visceral pain scores,the number of c-fos positive cells in LC and content of NA in the spinal cord were significantly increased in VP,DEX and AP groups (P＜0.05).Compared with group VP,the cumulative visceral pain scores,the number of c-fos positive cells in LC and content of NA in the spinal cord were significantly decreased in DEX and AP groups (P＜0.05).Compared with group DEX,the cumulative visceral pain scores,the number of c-fos positive cells in LC and content of NA in the spinal cord were significantly increased in group AP (P＜0.05).Conclusion Dexmedetomidine can alleviate visceral pain in rats,and the mechanism is partially related to activating α2 adrenergic receptors in LC.%目的 评价右美托咪定对大鼠内脏痛的影响及蓝斑核α2肾上腺素能受体在其中的作用.方法 成年雄性健康SD大鼠32只,体重250～ 300 g,采用随机数字表法分为4组(n=8):对照组(C组)、内脏痛组(VP组)、右美托咪定组(DEX组)和α2肾上腺素能受体拮抗剂阿替美唑组(AP组).AP组肌肉注射阿替美唑522 μg/kg,C组、VP组和DEX组肌肉注射等容量生理盐水;肌肉注射后10 min,DEX组和AP组尾静脉注射右美托咪定10 μg/kg,C组、VP组尾静脉注射等容量生理盐水;尾静脉注射后15 min,VP组、DEX组和AP组腹腔注射0.9％乙酸10 ml/kg制备内脏痛模型.于腹腔注射乙酸后60 min内记录内脏痛累计评分.于腹腔注射乙酸后2h时,采用免疫组化法检测蓝斑核c-fos阳性细胞数,采用酶联免疫吸附法检测脊髓去甲肾上腺素(NA)含量.结果 与C组比较,VP组、DEX组和AP组内脏痛累计评分、蓝斑核c-fos阳性细胞数和脊髓NA含量升高(P＜0.05);与VP组比较,DEX组和AP组内脏痛累计评分、蓝斑核c-fos阳性细胞数和脊髓NA含量降低(P＜0.05);与DEX组比较,AP组内脏痛评分、蓝斑核c-fos阳性细胞数和脊髓NA含量升高(P＜0.05).结论 右美托咪定可减轻大鼠内脏痛,其部分机制与激动蓝斑核α2肾上腺素能受体有关.
