中文摘要：

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。

英文摘要：

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-eatenin 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 immunohistoehemistry in SVZ area. The expression level of 13-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-eatenin signal.