小鼠脑室下区细胞增殖能力随年龄增加逐渐下降与β-catenin的相关研究

目的:脑内成体干细胞状态和年龄的关系非常密切,本研究探讨小鼠老化过程中脑室下区(subven-tricular zone,SVZ)内成体干细胞随年龄增加增殖活性的变化和脑内β-catenin信号的相关性。方法:C57B/L小鼠分别饲养至2,12,18月时处死,各组动物处死前腹腔注射BrdU(60 mg/kg,处死前3 d开始注射,连续注射3 d,1次/d)。部分动物断头取脑,冰台上游离前额皮层,冷冻备用,部分动物灌注固定,连续冠状冰冻切片备用。利用免疫组织化学方法检测SVZ区BrdU和Ki67表达。利用Western blot技术检测前额皮层内β-catenin的表达水平。结果:12,18月时小鼠SVZ区BrdU和Ki67阳性细胞的数量与2月时比较明显有所减少(P<0.05)。Western blot结果可见前额皮层内β-catenin的表达水平在2月时达高峰,12月和18月时逐渐减少。结论:SVZ区干细胞的增殖能力随年龄增加逐渐下降可能与脑内β-catenin信号的减弱有关。

Decline of progenitor cell proliferation with aging associated with β-catenin signaling in subventricular zone of mouse

Objective: The state of adult stem cells in brain has a very close relationship with age.The aim of this study was to evaluate the proliferative activity of stem cells in subventricular zone(SVZ) area with aging,and to explore the relevance with β-catenin signal in a brain.Methods: C57B/L mouse were respectively raised for 2 months(2 months),12 months(12 months) and 18 months(18 months),then sacrificed after injection of BrdU for three times through intraperitoneal(60 mg/kg,one time a day).Some mice were sacrificed and brains were removed on the ice plate for preparing tissue homogenate.Some mice were perfused with 4% paraformaldehyde for fixation,and then the serials coronal sections were made by using cryostat.BrdU and Ki67 expression were detected with immunohistochemistry in SVZ area.The expression level of β-catenin in prefrontal cortex was detected by using Western blot.Results: The number of BrdU-and Ki67-positive cells in SVZ significantly decreased in 12 months mice and 18 months mice compared with that the 2 months mice(P<0.05).Western blot results showed that the expression level of β-catenin in prefrontal cortex was the highest in 2 months mice,then gradually decreased in 12 months and 18 months mice.Conclusion: The proliferative capacity of progenitor cells in SVZ is reduced with aging and this change is associated with the decline of β-catenin signal.