磷酸化的细胞周期相关蛋白在大鼠海马神经元发育和老化过程中的表达

目的： 观察正常Wistar大鼠发育及老化过程中海马神经元磷酸化的细胞周期相关蛋白的表达，探讨这一过程中海马神经元的细胞周期的变化以及磷酸化细胞周期相关蛋白在其中的调控作用。方法：采用免疫荧光方法观察不同发育时期(1天、11天、1月、3月、15月) 磷酸化周期素依赖激酶2（CDK2）、磷酸化细胞分裂周期激酶2（CDC2）、磷酸化视网膜母细胞瘤（Rb）蛋白表达的规律，并应用Western blotting方法测定不同阶段大鼠海马内磷酸化CDK2、磷酸化CDC2、磷酸化Rb的含量。结果：在各年龄组中神经元特异性核蛋白（NeuN）阳性细胞数量随着年龄增加而逐渐减少，提示神经元数量随年龄的增加而逐渐减少。磷酸化CDK2、磷酸化Rb阳性细胞的数量随着年龄增加而逐渐增多，老年组增加明显，与其它各组间有显著差异，磷酸化CDC2阳性细胞在各年龄组神经元中表达量均较低；蛋白定量亦提示老年组磷酸化CDK2、磷酸化Rb的含量较其它组明显增高。结论：海马神经元数量随年龄增加逐渐减少，而其中磷酸化CDK2和磷酸化Rb却随年龄的增长逐渐增多，提示老化过程中部分神经元再次进入细胞周期，说明磷酸化细胞周期相关蛋白可能参与了这一过程中海马神经元的凋亡。

Expression of phosphorylated cell cycle related proteins in developing and aging rat hippocampus

AIM: To observe the expression of phosphorylated cell cycle related proteins cyclin-dependent kinase (CDK) and the retinoblastoma protein (Rb) in the developing and aging rat hippocampus. METHODS: The immunofluorescent staining for anti-phospho- CDK2, anti-phospho- CDC2, anti-phospho-Rb and anti-NeuN antibodies was used to determine their expressions and distributions in Wistar rat hippocampus at different ages. The expressions of phosphorylated cell cycle related proteins were also assessed by Western blotting analysis. RESULTS: (1) The number of neurons of CA1 area in hippocampus decreased during the period from 1 day to 15 months. (2) The positive expressions of phospho- CDK2 and phospho-Rb increased with aging. (3) No apparent change in the expression of phospho- CDC2 in the hippocampus of all the five groups was observed. CONCLUSION: The expressions of phospho-CDK2 and phospho-Rb suggest that differentiated neuron can re-enter the cell cycle and more neurons enter the cell cycle in the aged rat brain. Re-entering the cell cycle of differential neurons probably results in apoptosis.