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目的 研究不同发育时期大鼠脑中Cdk5 ,p35 ,p39的表达及Cdk5激酶活性变化。 方法 免疫印迹测定胚胎 12天至出生后 18个月大鼠脑中Cdk5 ,p35 ,p39的表达 ,通过测定Cdk5特定底物 组蛋白H1被磷酸化的程度检测鼠脑中Cdk5激酶活性。结果 从胚胎 12天至出生 7天 ,大鼠脑中Cdk5蛋白水平逐渐增加到峰值并保持至 18个月龄。在胚胎 12天时 ,Cdk5激酶活性和p35的蛋白水平较低 ,在胚胎 18天至出生 14天期间最高 ,然后在 3个月龄至 18个月龄的成年鼠和老年鼠脑中逐渐减少。与之相比 ,p39的表达方式与Cdk5和p35正好相反。自P14至 18M龄鼠脑中 ,大脑皮质及海马的 p35表达和Cdk5激酶活性高于小脑或纹状体。结论 大鼠发育早期 ,Cdk5激酶复合物的活化与神经发育密切相关 ,其生理作用在大脑皮质及海马有区域特异性。
Objective To study the expression of Cdk5, p35 and p39 and the changes of Cdk5 kinase activity in rat brain at different developmental stages. Methods The expression of Cdk5, p35 and p39 in rat brain from 12 days after birth to 18 months after birth was measured by immunoblotting. Cdk5 kinase activity in rat brain was detected by measuring the degree of phosphorylation of Cdk5 specific substrate histone H1. Results From 12 days embryo to 7 days of birth, the Cdk5 protein level in rat brain gradually increased to its peak and remained at 18 months of age. The Cdk5 kinase activity and the protein level of p35 are lower at embryonic day 12 and are highest between embryonic day 18 and 14 days of birth and then gradually decrease in the brains of adult and old mice aged 3 months to 18 months. In contrast, the expression of p39 is exactly the opposite of that of Cdk5 and p35. The p35 expression and the Cdk5 kinase activity in cerebral cortex and hippocampus were higher in cerebellum and striatum than those in cerebellum or striatum from P14 to 18M mice. Conclusion The activation of Cdk5 kinase complex is closely related to the neurodevelopment in the early stage of rat development. The physiological function of Cdk5 kinase complex is region specific in cerebral cortex and hippocampus.