非阿片类药物KOR激动剂Salvinorin A减轻前脑缺血再灌注大鼠脑水肿的作用

The non-opioid KOR agonist Salovinorin A reducing brain edema in rats with forebrain ischemia and reperfusion

目的探讨大鼠前脑缺血再灌注(I/R)损伤后,Kappa阿片受体(KOR)激动剂Salvinorin A(SA)减轻脑水肿的机制。方法成年健康雄性Sprague-Dawley(SD)大鼠随机分为5组(n=10):假手术组、I/R组、DMSO(SA溶剂)组、SA组和Norbinaltorphimine(nor-BIN,KOR拮抗剂)+SA组。夹闭双侧颈动脉联合低血压诱发前脑缺血10 min,在缺血后即刻给予DMSO、SA和nor-BIN+SA。再灌注后24 h处死大鼠,取其海马组织做病理,采用末端转移酶d UTP缺口末端标记(TUNEL)及免疫组织化学检测AQP4蛋白水平,用干-湿重法评估脑含水量。结果与假手术组比较,I/R组海马脑含水量增加(P<0.01);SA组和I/R组相比,海马脑含水量显著下降(P<0.01);nor-BIN+SA组脑含水量显著高于SA组(P<0.05)。前脑缺血再灌注后24 h,与I/R和DMSO组比较,SA组显著减少海马神经细胞坏死和凋亡(P<0.01),而nor-BIN可抵消这一作用。与假手术组比较,海马的AQP4蛋白水平,在I/R组显著增加(P<0.01);与I/R组比较,SA组显著下降(P<0.01);nor-BIN+SA组AQP4的蛋白水平和SA组相比明显增加(P<0.05)。结论 SA可以明显减轻前脑缺血后的脑水肿,减轻脑损伤,抑制AQP4的蛋白水平,其作用可能和KOR相关。

Objective To discuss the mechanism of Kappa opioid receptor（KOR） agonist Salvinorin A（SA） on decreasing brain edema after forebrain ischemia-reperfusion（I/R） injury in rats. Methods Male Sprague-Dawley rats were divided into 5 groups（n=10）： sham operation group,I/R group,DMSO（vehicle） group,SA group and Norbinaltorphimine（nor-BIN,KOR antagonist） ＋SA group. Forebrain ischemia was performed by low artery pressure with bilateral carotid artery occlusion for 10 minutes. Intervenes（DMSO,SA,nor-BIN＋SA） were performed after forebrain ischemia instantly.The animals were sacrificed 24 hours after reperfusion. The hippocampus was taken for pathology,and Td T-mediated d UTP nick end labeling（TUNEL） and immunohistochemical test were used for AQP4 detection. The wet-dry weight method was used to assess brain water content. Results Compared with sham operation group,hippocampus water content increased in I/R group（P〈 0.01）. Hippocampus water content was significantly lower in SA group than that in I/R group（P 〈0.01）. Hippocampus water content was significantly higher in nor-BIN＋SA group than that in SA group（P〈 0.05）. Compared with I/R and DMSO groups,hippocampus neurosis and apoptosis were alleviated significantly with treatment of SA 24 h after forebrain I/R（P〈 0.01）,which effect was blunted by nor-BIN. Compared with sham operation group,AQP4 expressed in hippocampus was promoted by I/R（P〈 0.01）. Compared with I/R group,AQP4 expressed was depressed in SA group（P〈 0.01）. The expression of AQP4 increased significantly with treatment of norBIN＋SA compared with SA（P〈 0.05）. Conclusion SA can reduce cerebral edema after forebrain ischemia and brain damage by inhibition of AQP4. Its mechanism may be correlated with KOR.