吗啡预处理诱导小鼠离体海马脑片氧糖剥夺耐受中PKCδ的作用

Effect of PKCdeta on cerebral ischemic/hypoxic tolerance induced by morphine preconditioning

目的探讨吗啡预处理诱导小鼠离体海马脑片氧糖剥夺耐受形成的机制。方法以离体小鼠海马脑片氧糖剥夺(OGD)模拟脑缺血再灌注损伤模型,以孵育液乳酸脱氢酶(LDH)漏出率及脑片细胞存活率为指标,探讨吗啡3μmol/L预处理对不同程度OGD损伤小鼠海马脑片神经元的保护作用,用Western blot检测PKCδ表达。结果吗啡预处理明显提高OGD5、10及20 min脑片细胞存活率,使孵育液LDH漏出减少(P<0.05)。OGD后即刻和再灌注2 h后,缺糖缺氧组PKCδ膜相关成分蛋白表达明显增高,同时胞质部分蛋白表达明显减少(P<0.05),吗啡预处理对PKCδ膜转位变化无明显影响。结论吗啡预处理减轻小鼠离体海马脑片20 min以内氧糖剥夺损伤,其机制可能与PKCδ的膜转位激活无关。

Objective To determine the mechanism of morphine preconditioning（MP） on brain ischemie/hypoxic tolerance in the bippocampus slices of mouse. Methods Hippocampus slices were exposed to oxygen-glucose deprivation （OGD） to mimic ischemia-reperfusion injury in vitro. The injuries were assessed by lactic dehydrogenase （LDH） release rate and cell survival rate of slices 2,3,5-triphenyhetrazolium chloride （TTC） to evaluate the protective effects of MP. Western blot analysis was used to identify the expression of PKCS. Results In hippocampal slices preconditioned with morphine, cell survival rate was increased and LDH release rate was decreased significantly compared with OGD 5 min, 10 min and 20 min （P 〈 0. 05 ）. Immediately and at the end of 2 h reperfusion after OGD 10 min, the particulate fraction of PKCδ increased significantly, concomitantly with a corresponding decrease in the cytosolic fraction （P 〈 0. 05）. The increased membrane transloeation of PKC8 was not inhibited by MP. Conclusion MP can reduce OGD-induced neuronal injuries, the protective effects were observed for periods of OGD equal to or shorter than 20 min. PKCδ membrane translocation might not be involved in the neumproteetion.