短期丰富生存环境干预下中老年大鼠海马结构有髓神经纤维的性别差异

Sex differences of short-term enriched environment on myelinated nerve fibers in the hippocampal formation of middle-aged rats

目的研究短期丰富生存环境干预下正常中老年大鼠海马结构有髓神经纤维的性别差异。方法将20只14月龄的SD大鼠(雌雄各10只)随机均分为丰富生存环境组与普通环境组,前者在丰富生存环境条件下饲养4个月,后者在普通环境中饲养4个月,运用透射电子显微镜和体视学方法对两组大鼠海马结构有髓神经纤维进行定量研究。结果普通环境组雌性大鼠海马结构内有髓神经纤维的总体积、平均直径均显著大于雄性大鼠(P<0.05),而海马结构总体积、海马结构内有髓神经纤维的总长度雌雄两组之间不存在显著性差异(P>0.05)。丰富生存环境组雌性大鼠海马结构内有髓神经纤维的平均直径显著小于雄性大鼠(P<0.05),而海马结构总体积、海马结构内有髓神经纤维的总体积、总长度雌雄两组之间不存在显著性差异(P>0.05)。结论普通环境组和丰富环境组中老年大鼠海巴结构有髓神经纤维存在的性别差异,提示雌、雄性中老年大鼠对短期丰富生存环境干预的反应不同。

Objective To investigate the sex differences of the myelinated nerve fibers in the hippocampal formation of mid-aged standard and enriched rats. Methods Twenty 14-month Sprague-Dawley （SD） rats, 10 female and 10 male rats, were randomly divided into enriched group and standard group. Enriched rats were reared in enriched environment and standard rats were reared in standard environment for 4 months. Then, the total volume of the hippocampal formation and the myelinated nerve fibers in the hippocampus were quantita- tively estimated by transmission electron microscopy and stereological methods. Results The total volume and mean diameter of the myelinated nerve fibers in the hippocampal formation of standard female rats were significantly bigger than those of standard male rats （P 〈 0.05 ）, but there was no statistically significant change of the total volume of the hippocampal formation and the total length of the myelinated nerve fibers in the hippocampal formation of standard female rats when compared to those of standard male rats （ P 〉 0.05 ）. The mean diameter of the myelinated nerve fibers in the hippocampal formation of enriched female rats was significantly smaller than that of enriched male rats （P 〈 0.05 ）, but there was no statistically significant difference of the total volume of the hippocampal formation and the total volume and total length of the myelinated nerve fibers in the hippocampal formation of enriched female rats when compared to those of enriched male rats （ P 〉 0.05 ）. Conclusion The sex differences of the myelinated nerve fibers in the hippocampal formation of mid-aged standard and enriched rats are significantly different, in the mid-aged male and female rats is different. which indicates the response to the enriched environment.