短期丰富生存环境对老年雄性大鼠大脑白质及白质内有髓神经纤维的影响

目的 探讨短期丰富生存环境干预对老年雄性大鼠大脑白质及白质内有髓神经纤维的影响.方法 将20只24月龄雄性SD大鼠分别在丰富生存环境条件和普通标准环境下饲养4个月后,从每组随机抽取4只大鼠,用透射电子显微镜和体视学方法比较两组大鼠大脑白质及白质内有髓神经纤维的改变. 结果 丰富生存环境组大鼠的白质总体积,白质内有髓神经纤维总长度和总体积,有髓神经纤维轴突总体积分别较标准对照组显著增大,但有髓神经纤维平均内径、外径、髓鞘总体积、髓鞘平均厚度、髓鞘平均内、外周长、有髓神经纤维断面面积、髓鞘断面面积及轴突断面面积较对照组均无明显差异. 结论 短期丰富生存环境干预对24月龄雄性大鼠的大脑白质和白质内有髓神经纤维均有明显的影响.提示短期丰富生存环境可能促使老年雄性大鼠白质内已经发生脱髓鞘改变的有髓神经纤维出现髓鞘再生.

Effects of short-term enriched environment on the white matter and the myelinated fibers in the white matter of aged male rats

Objective To investigate the effects of short-term enriched environment on the white matter and the myelinated fibers in the white matter of aged male rats. Methods Twenty 24-month old male SD rats were reared in enriched environment (EE) or standard environment (SE) for 4 months, respectively. Four rats were randomly selected from each group. The white matter and the myelinated fibers in the rat white matter were quantitatively investigated with transmission electronic microscopy and stereological techniques. Results The white matter volume, the total length and total volume of the myelinated fibers in the white matter and the total volume of axons in the white matter of EE rats were all significantly larger than those of SE rats. The mean inner diameter and outer diameter of myelinated fibers, the total volume of myelin sheaths, the mean thickness of myelin sheaths, the mean inner perimeter and outer perimeter of myelin sheaths and the cross-sectional areas of the myelinated fibers, myelin sheaths and axons were not significantly different between EE and SE rats. Conclusion Short-term enriched environment has positive effects on the white matter and myelinated fibers in the white matter in 24-month male rats. These results suggest that short-term enriched environment might induce the remyelination of the demyelinated fibers in the white matter of aged male rats.