新生大鼠缺氧缺血性脑损伤蛋白激酶C与c-fos基因表达关系的探讨

Study on the roles of protein kinase C and c-fos gene expression in the pathogenesis of hypoxic-ischemic brain injury in neonatal rat brain

目的 :探讨蛋白激酶 C与 c fos基因蛋白 (c Fos)表达在新生大鼠缺氧缺血性脑损伤时的作用机制。方法 :蛋白激酶 C蛋白定量采用 L owry法 ;蛋白激酶 C活性测定采用γ 32 P催化活性测定法 ;c Fos表达采用免疫组织化学染色法。结果 :与对照组相比 ,缺血、缺氧 2 0分钟后 0、4、12、2 4、4 8、72小时及 7日组新生鼠脑皮质、海马神经细胞胞膜蛋白激酶 C活性降低 (t=3.5 0 ,P<0 .0 5 ;t=3.35 ,P<0 .0 1) ;脑皮质神经细胞胞浆蛋白激酶 C活性增高 (t=4 .2 6 ,P<0 .0 1) ;海马神经细胞胞浆活性变化不大 ;上述改变在缺血、缺氧后 14日组基本恢复正常。新生鼠缺血、缺氧后即刻脑组织各部分即有不同程度的 c Fos表达 ,且于缺血、缺氧后 4小时达高峰 ,以后强度逐渐降低 ,并持续至 72小时。 c Fos表达在脑皮质以 ～ 层明显 ,海马以 CA1、海马齿状回明显 ,CA3也有表达 ,丘脑 c Fos表达稍有增加。结论 :缺血、缺氧激活的蛋白激酶 C可调节 c fos基因表达 ,持续的蛋白激酶 C活性降低及 c Fos表达参与了神经细胞的损伤过程。

Objective:To investigate the changes in protein kinase C (PKC) and cfos gene as well as protein expression (cFos)during hypoxicischemic (HI) brain damage (HIBD) in neonatal rats.Methods:The protein concentration was determined by Lowry's method.PKC activity was measured by the incorporation of 〔γ 32 P〕 into a specific substrate peptide in the cytosolic and particulate fraction,respectively.cFos expression was determined by immunohistochemistry staining assay.Results:Compared with controls,PKC activities in particulate fractions in both cerebral cortex and hippocampus decreased ( P <0 05),whereas increased in cytosol in cerebral cortex( P <0 01) and remained within normal range in cytosol in hippocampus at 0,4,12,24,48,72 hours,and on days 7 and 14 after HI for 20 minutes.All these changes restored to normal range on day 21 after HIBI.Similarly,cFos was expressed in different parts of brain immediately after HI and peaked at 4 hours, afterward its density were gradually decreased and lasted up to 72 hours.cFos expression was obvious in ⅡⅤ layers of cortex,CA1 and dentate gyrus of hippocampus respectively,and it was slightly increased in thalamus. Conclusions: HIactivated PKC can regulate cfos gene expression,PKC down regulation and cfos gene expression might be involved in the development of neuron death during HIBD.