预刺激小脑顶核对缺血再灌注大鼠脑蛋白激酶C同工酶表达的影响

背景预先电刺激小脑顶核(fastigialnucleus,FN)具有明确的缺血脑保护作用,但其机制尚不十分清楚.研究缺血诱导的蛋白激酶C(proteinkinaseC,PKC)同工酶γ,δ异常表达,可使人们从新的角度去认识和探索预先电刺激FN缺血脑保护作用的机制.目的观察预刺激脑缺血大鼠小脑顶核不同时相PKC同工酶γ,δ蛋白表达.设计随机对照实验.地点和对象实验地点重庆医科大学神经病学研究所.Wistar雄性大鼠48只,随机将动物分为单纯缺血再灌注组(I/R),假手术组(I/R'),刺激小脑齿状核(dentatenucleus,DN)I/R组(I/RDN),刺激小脑FNI/R组(I/PFN);其中I/PDN,I/RFN又分别分为3组缺血前1,4,7d刺激.每组动物为6只.干预采用线栓法大鼠大脑中动脉栓塞再灌注模型,缺血时间均为1.5h再灌注24 h;于缺血前1,4,7 d分别刺激小脑顶核、齿状核1 h.主要观察指标以尾状核冠状切面作为观察对象,应用免疫组织化学方法观察对照组、假手术组、刺激小脑顶核组和齿状核组PKCγ,δ的表达情况.结果缺血前1,4,7d刺激小脑齿状核各组、单纯缺血再灌注组、假手术组PKCγ,δ阳性细胞数比较无显著性差异(P＞0.05),而缺血前1,4,7 d预刺激小脑顶核能明显抑制PKCγ,δ蛋白的表达(t=2.372～6.632,P＜0.05).结论缺血性脑损害能诱导PKC γ,δ蛋白表达上调,预先电刺激小脑顶核的缺血脑保护作用可能与其下调PKCγ,δ蛋白表达有关.

Impact of electricstimulation preconditioning in fastigial nucleus on the expression of protein kinase Cisoenzyme in cerebral ischemia-reperfusion rat

BACKGROUND: It has definite cerebral ischemic protective reaction to electrically stimulate fastigial nucleus(FN) through preconditioning but without clear mechanism available. It could lead to exploration and understanding of the mechanism of the protective reaction of preconditioning in FN with electric stimulation from a new angle by investigating the abnormal expression of protein kinase C(PKC) isoenzyme γ, δ induced by ischemia.OBJECTIVE: To observe the expression of PKC isoenzyme γ and δ at different time phases during preconditioning of electric stimulation in FN in cerebral ischemic rats.DESIGN: A randomized controlled study.SETTINGS and MATERIALS: Settings: Neurologic Institute of Chongqing University of Medical Sciences. Participants: Forty-eight male Wistar rats were randomly allocated into ischemic-reperfusion group(I/R),sham-operation group(I/R' ), dentate nucleus(DN) stimulation I/R group (I/RDN), and FN stimulation I/R group(I/RFN), in which I/RDN and I/RFN groups were divided into three subgroups respectively of 1, 4 and 7-day pre-ischemic stimulation subgroups. Each group had 6 rats.METHODS: The model of ischemic reperfusion in rats was established by middle cerebral artery occlusion with a nylon monofilament suture. Ischemic time was 1.5 hours and reperfusion time was 24 hours. DN and FN were stimulated respectively for 1 hour at 1, 4 and 7 days before ischemia.MAIN OUTCOME MEASURES: Coronal section of cauda nucleus was the observatory subjects. The expression of PKC γ and δ in four groups were observed through immunohistochemical technique.RESULTS: There were no differences in PKC γ and δ IR-positive cells among each subgroups of I/RDN, I/R, and I/R' groups( P ＞ 0.05), however, the preconditioning of stimulation in FN at 1, 4 and 7 days before ischemia could significantly inhibit the expression of PKC γ and δ proteins (t=2.373-6.632, P ＜0.05).CONCLUSION: Cerebral ischemic damage can induce an increase of PKC γ and δ proteins. The protective reaction of electric stimulation preconditioning in FN on cerebral ischemia may relate with its inhibitive reaction in the expression of PKC γ and δ proteins.