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目的：观察不同年龄大鼠大脑神经细胞核染色质１０ｎｍ和３０ｎｍ纤维核小体排布特征，探讨老化过程导致大脑神经细胞核转录活性衰退的分子机制。方法：选用微球菌核酸酶（ＭＣＮ）为染色质结构识别探针，经蔗糖密度梯度离心、凝胶电泳，可显示不同龄大鼠大脑染色质结构特征的变化。结果：幼年鼠、成年鼠和老年鼠大脑染色质１０ｎｍ纤维核小体重复长度分别保持在（１７６±４）、（１７５±６）和（１７８±７）ｂｐ水平上；而３０ｎｍ抗酶解寡聚体核小体数目为：酶解３０％染色质时，分别是（３９±０．４７）、（４２±０．２６）和（４６±０．０２）；酶解５０％染色质时，则是（１８±０．１２）、（２１±０．４１）和（２６±０．２７）。结论：大鼠大脑细胞核１０ｎｍ染色质纤维核小体重复长度不受老化过程影响；３０ｎｍ纤维抗酶解寡聚体大小与年龄呈正相关，提示大鼠老化过程大脑染色质构象发生不利于ＭＣＮ酶解的变化，这可能是老化导致转录功能衰退的重要原因之一
OBJECTIVE: To observe the distribution of 10 nm and 30 nm nuclear chromatin of rat brain nuclei in different age groups, and to explore the molecular mechanism of aging leading to the decline of nuclear transcriptional activity of brain neurons. Methods: Using micrococcal nuclease (MCN) as chromatin structure recognition probe, the sucrose density gradient centrifugation and gel electrophoresis showed the changes of chromatin structure in different age rats. Results: The reproducibility of 10 nm nuclear nucleosomes in juvenile, adult and aged mice remained at (176 ± 4), (175 ± 6) and (178 ± 7) bp, respectively. However, The number of meronucleosomes was (39 ± 0.47), (42 ± 0.26) and (46 ± 0.02), respectively, when enzymatic hydrolysis of 30% chromatin; (18 ± 0.12), (21 ± 0.41) and (26 ± 0.27), respectively. CONCLUSION: The length of 10nm chromatin nucleosome repeat in rat cerebrum nucleus is not influenced by aging process. The size of 30nm fiber anti-enzymolysis oligomer is positively correlated with age, suggesting that chromatin conformation of rat brain during aging is not conducive to MCN enzymolysis Which may be one of the important reasons for the decline of transcription function caused by aging