开胸术后慢性痛大鼠脊髓背角神经元ATP敏感型钾通道表达的变化

Change in expression of ATP-sensitive potassium channels in spinal dorsal horn neurons in rats with chronic post-thoracotomy pain

目的评价开胸术后慢性痛大鼠脊髓背角神经元ATP敏感型钾通道（KATP通道）表达的变化。方法雄性SD大鼠20只，体重250～350g，采用随机数字表法，将其随机分为假手术组和开胸术后慢性痛组，每组10只。于术前1d、术后1、5、10、15、20、25、30d时分别测定机械痛阈，并行冷丙酮实验，记录1min内大鼠后爪抓挠皮区次数；于术后30d时处死大鼠，取颈至上胸段脊髓，免疫组化法检测KATP通道的表达水平。结果与假手术组比较，开胸术后慢性痛组大鼠术后5～30d时机械痛阈降低，术后20～30d时后爪抓挠皮区次数增加，术后30d时胸段脊髓背角神经元KATP通道表达下调（P〈0．05）。结论开胸术后慢性痛大鼠脊髓背角神经元KATP通道表达下调，该变化可能参与了开胸术后慢性痛的病理生理机制。

Objective To＇ evaluate the change in the expression of ATP-sensitive potassium （KATP） channels in spinal dorsal horn neurons in rats with chronic post-thoracotomy pain （CPTP）.Methods Twenty male SD rats, weighing 250-350 g, were randomly divided into 2 groups （ n = 10 each） ： sham operation group and CPTP group. The animals were anesthetized with 10% chloral hydrate 300 mg/kg, tracheostomized and mechanically ventilated. At 1 d before operation, and at 1, 5, 10, 15, 20, 25 and 30 d after operation, paw withdrawal threshold to von Frey filament stimulation was measured and the acetone test was performed. The responses of the hindpaw to the acetone test within 1 min were recorded. The rats were sacrificed at 30 d after operation, and the cervical and upper thoracic segments of the spinal cord were removed to detect the expression of KATe channels in spinal dorsal horn neurons by immuno-histochemistry. Results Compared with sham operation group, mechanical pain threshold was significantly decreased at 5-30 d after operation, the response frequency was significantly increased at 20-30 d after operation, and the expression of KATP channels in spinal dorsal horn neurons in the thoracic segments was down-regulated at 30 d after operation in CPTP group （ P 〈 0.05）. Conclusion The expression of KATP channels in spinal dorsal horn neurons is down-regulated in rats with CPTP, which may be involved in the pathophsiology mechanism of CPTP.