老年大鼠肝脏细胞核被膜核苷三磷酸酶活性和mRNA转运的改变

Alternation in neucleotide triphosphatase activity and mRNA transport of nuclear envelope in aged rat liver

目的 探讨老年大鼠肝细胞蛋白质合成障碍的细胞分子机制。 方法 体外孵育老年Ｗｉｓｔａｒ 大鼠肝脏组织切片后，制备肝组织匀浆和肝细胞核被膜，分别测定肝脏组织三磷酸腺苷（ＡＴＰ）含量、肝细胞核被膜核苷三磷酸酶（ＮＴＰａｓｅ）活性和成熟ｍ ＲＮＡ〔ｐｏｌｙ（Ａ＋ ）ｍ ＲＮＡ〕的出核转运速率，并与断奶鼠（对照组）进行比较。 结果 在基础情况和胰岛素刺激后老年鼠肝细胞核被膜ＮＴＰａｓｅ 活性均明显低于对照组，以ＡＴＰ为底物时，分别为（７０．３±６．８）和（９０．１±８．２）、（１２６．３±１１．４）和（１６８．４±１３．３）ｎｍ ｏｌＰｉ·ｍ ｇ－ １ Ｐｒ·ｍ ｉｎ－ １；以三磷酸鸟苷（ＧＴＰ）为底物时，分别为（６１．１±７．０）和（１３５．６±１１．４）、（７８．９±６．９）和（２１４．３±１７．８）ｎｍ ｏｌＰｉ·ｍ ｇ－ １ Ｐｒ·ｍ ｉｎ－ １，两组各指标比较，差异均有显著性（均为Ｐ＜ ０．０１）；细胞核被膜对于ｐｏｌｙ（Ａ＋ ）ｍ ＲＮＡ转运速率亦明显低于对照组（Ｐ＜０．０１）；但老年鼠与对照组肝脏组织ＡＴＰ含量之间差异无显著性（Ｐ＞ ０．０５）。 结论 老年鼠肝细胞核被膜对于ｐｏｌｙ （Ａ＋ ） ｍ

Objective To investigate the cellular and molecular mechanism of protein synthesis disorder in aged rat liver. Methods The hepatic tissue slices both from 24 month (aged ) rats and 4 week (control) rats were incubated with K H buffer. Liver nuclear envelope was prepared to measure nucleotide triphosphatase (NTPase) activities and poly (A +) mRNA export rate. Results When ATP and GTP were used as substrate both the basal and insulin stimulated NTPase activities in nuclear envelope and poly (A +) mRNA export from the aged rats were significantly reduced as compared with those from the control rats, while ATP contents in liver from both the aged rats and control rats had no significant statistical difference ( P >0 05). Conclusions The mRNA export rate of hepatic nuclear envelope from aged rats decreases significantly and the mechanism might be related with the reduction of NTPase activity in hepatic nuclear envelope.The decrease of its activity may be an important cause for the decrease of protein synthesis.