异氟醚、七氟醚和地氟醚预处理对脑缺血再灌注损伤大鼠海马CBS／H_2S、iNOS／NO和HO-1／CO的影响

Effects of isoflurane,sevoflurane and desflurane preconditioning on CBS/H_2S,iNOS/NO and HO-1/CO in hippocampus after global cerebral ischemia-reperfusion in rats

目的研究异氟醚、七氟醚和地氟醚预处理对脑缺血再灌注损伤大鼠海马CBS／H2S、iNOS／NO和HO-1／CO的影响,探讨吸入麻醉药脑保护作用的机制。方法30只Wistar大鼠随机分为5组(n=6):对照组(C组)、脑缺血再灌注组(I／R组)、异氟醚组(Ⅰ组)、七氟醚组(S组)和地氟醚组(D组)。采用四动脉阻断法建立大鼠全脑缺血再灌注模型。Ⅰ组、S组和D组夹闭两侧颈总动脉前分别吸入氧气+0．65 MAC的异氟醚、七氟醚和地氟醚30 min,C组和I／R组吸入氧气。缺血20 min,再灌注12 h后处死大鼠,取海马,测定大鼠海马组织中H2S、NO、CO、cAMP和cGMF。含量和CBS、iNOS和HO活性以及CBS—mRNA、iNOS—mRNA和HO-1-mRNA的表达水平;电镜下观察海马线粒体的变化。结果与C组相比,I／R组海马组织CO、H2S、NO、cAMP、cGMP含量和HO、CBS、iNOS活性升高,CBS-mRNA、iNOS-mRNA和HO-1-mRNA表达升高,海马神经细胞线粒体变性率升高(P<0．01);与I／R组相比,Ⅰ组、D组和S组CO含量和HO活性升高,H2S、NO、cAMP含量和CBS、iNOS活性降低,CBS—mRNA和iNOS-mRNA表达降低而HO-1-mRNA表达升高,线粒体变性率降低(P<0．05或0．01)。结论异氟醚、七氟醚和地氟醚预处理可通过抑制CBS／H2S、iNOS／NO,激活HO-1／CO,减轻了大鼠脑缺血再灌注损伤。

Objective To investigate the effects of preconditioning with isoflurane, sevoflurane and desflurane on cystathionine beta synthase （ CBS ）/hydrogen sulfide （ H2 S ）, hemeoxygenase- 1 （ HO- 1 ）/carbon monoxide （CO） and inducible nitric oxide synthase （iNOS）/nitric oxide （NO） in hippocampus after global cerebral isehemia-reperfusion （I/R） and the mechanism of neuroproteetion by inhalational anesthetics. Methods Thirty male Wistar rats aged 3-4 months weighing 180-220 g were randomly divided into 5 groups （ n = 6 each） ： groupⅠ control; groupⅡ I/R; group Ⅲ isoflurane; group Ⅳ sevoflurane and group Ⅴ desflurane. Global cerebral I/R model was established by 4 vessel occlusion method. The vertebral arteries were electrocauterized through the alar foramina of the 1 st cervical vertebra under pentobarbital anesthesia. The bilateral common carotid arteries （CCA） were reversibly occluded with atraumatic mini-clamps for 20 min followed by 12 h reperfusion. In group Ⅲ , Ⅳ , and V the rats inhaled 0.65 MAC isoflurane, sevoflurane and desflurane for 30 min respectively before occlusion of bilateral CCAs. The animals were killed and hippocampus was immediately removed at the end of 12 h reperfusion for （ 1 ） microscopic examination of mitochondrial structure and （2） determination of H2 S, CO, NO, cAMP and cGMP contents, the activity of CBS, iNOS and HO-1 and the expression of CBS mRNA, iNOS mRNA and HO-1 mRNA in hippocampus. Results After I/R the H2S, NO, CO, cAMP and eGMP contents, the CBS, HO, iNOS activity and the expression of CBS mRNA, iNOS mRNA and HO-1 mRNA were all significantly increased as compared to the control group （P 〈 0.01）. The H2S, NO and cAMP content; CBS and iNOS activity and CBS mRNA and iNOS mRNA expression were all significantly decreased while CO content, HO activity and HO-1mRNA were significantly decreased in the 3 inhalational anesthetic preconditioning groups （group Ⅲ, Ⅳ ,Ⅴ ） as compared with group Ⅱ （I/R）. The damaged to mitochondrial structure induced by I/R was mitigated by preconditioning with inhalational anesthetics. Conclusion Pharmacological preconditioning with isoflurane, sevoflurane or desflurane can protect the brain from I/R injury through inhibition of CBS/H2S, iNOS/NO and activation of HO-1/CO.