年龄对胰腺部分切除的小鼠胰岛细胞再生和凋亡的影响

Effects of age on islet regeneration and apoptosis in mice with pancreatectomy

目的 探讨年龄对胰岛细胞再生的影响,初步揭示胰岛再生的机制以及与老龄性糖尿病的关系.方法 对清洁级3月龄[n=12,体重（16.7±1.9）g]、6月龄[n=12,体重（25.4±2.3）g]、12月龄[n=12,体重（28.5±3.0）g]近交品系C57B6小鼠胰腺切除65%～70%,在饮用水中加入BrdU以标记增殖细胞,各组动物分别于1、2、4周处死取材,通过测量空腹血糖、静脉糖耐量并应用免疫组织化学的方法对胰岛细胞的再生以及胰岛细胞的凋亡进行全面的研究.所得数据通过Graphpad Prism 5.0软件的2-way ANOVA进行统计学处理.结果 在3月龄的年轻小鼠部分胰腺切除后,术后1、2、4周胰岛β细胞再生率分别为15.1%±10.0%、25.5%±8.1%、45.7%±14.6%;6月龄小鼠胰岛再生率分别为23.9%±8.7%、28.3%±7.6%和27.2%±5.7%;而对于12月龄老龄的小鼠,胰岛细胞再生率分别为4.4%±6.9%、6.1%±5.8%和5.1%±7.0%,用GraphPad Prism 5.0软件进行2-way ANOVA分析表明时间、年龄对胰岛再生均有影响（P＜0.0001,P＜0.05）,各组间差异有统计学意义.3月龄的小鼠1、2、4周胰岛β细胞凋亡率分别为2.7%±2.4%、3.7%±3.4%、3.1%±3.6%,12月龄的小鼠1、2、4周胰岛β细胞凋亡率分别为5.6%±1.4%、5.8%±4.3%、6.7%±2.6%,3月龄小鼠凋亡的β细胞数量明显少于12月龄的小鼠（P＜0.05）.结论 随着年龄的增长,小鼠胰岛β细胞的再生能力明显降低,并且更易发生凋亡.这可能是导致老龄人群糖尿病发病率升高的主要原因之一.

Objective To investigate the effect of age on pancreatic islet regeneration and to explore the underlying mechanisms and the relationship between aging and diabetes.Methods Three month old （body weight,（16.7±1.9） g,n=12）,6 month old （body weight,（25.4 ±2.3） g,n = 12）and 12 month old （body weight,（28.5 ±3.0） g,n = 12） inbred C57B6 mice （SPF grade） were underwent partial （65% -70% ） pancreatectomy （PPx） ,and the proliferating cells were labeled by BrdU in drinking water.Mice of each group were sarcrificed on 1,2 and 4 weeks respectively.By measuring fasting blood glucose level,IVGTT and also immunohistological analyses,to observe the PPx-induced metabolic changes and islet regeneration as well as islet apoptosis event. Data were analyzed in 2-way ANOVA by Graphpad Prism 5.0 software,and P values were calculated.Results For 3 month old mice,islet regeneration rates,after PPx for 1,2 and4 weeks were 15.1% ±10.0% 、25.5% ±8.1% 、45.7% ±14.6% respectively.For 6 month old mice,islet regeneration rates were 23.9% ±8.7%,28.3% ±7.6% and 27.2% ±5.7%,and for 12 month old mice,islet regeneration rates were 4.4% ±6.9%,6.1% ±5.8% and 5.1% ±7.0%.Analyzed by 2-way ANOVA （ Graphpad Prism 5.0 software）,it was showed that recovering time had obvious impact on β cell regeneration （ P 〈 0.0001 ）,and also aging （ P 〈 0.05 ）.The interaction of recovering time and aging had obvious impact （P〈0.05）.For apoptosis study,the apoptotic cells of 3 month old mice account for 2.7% ±2.4% ,3.7% ± 3.4% ,3.1% ± 3.6% of total cells （ 1,2 and 4 weeks respectively）.But for 12 month old mice,the data were 5.6% ± 1.4% ,5.8% ±4.3% ,6.7% ±2.6%,respectively.Three month old mice had less apoptotic cells compared with those of 12 month old mice （ P〈0.05）.Conclusions With aging,pancreatic islets clearly tend to lose their regenerative potential and become more susceptible to apoptosis.This could be one of the leading reasons that old people tend to have diabetes compared with younger ones.