断乳前丰富环境对即刻早期基因Arc的表达及长时记忆的影响

Effects of preweaning enrichment on activity-regulated cytoskeletal protein expression and long-term memory in rats

目的探讨断乳前丰富环境对大鼠海马即刻早期基因—活性调节的细胞骨架蛋白(activity-regula-ted cytoskeletal protein,Arc)的表达,以及对长时记忆的影响。方法4窝共40只新生SD大鼠,每窝随机分为对照组(n=20)和实验组(n=20),实验组大鼠生后10日龄至24日龄每天予以丰富环境暴露20min,对照组大鼠除不予以丰富环境暴露外,其余处理均与实验组相同。生后28d,两组大鼠予以旷场行为测试其自发活动,新物体识别测试评估其长时记忆能力,采用免疫印迹方法检测断乳前丰富环境对海马即刻早期基因Arc表达量的影响,并且通过免疫荧光的方法观察两组间Arc在海马CA1和DG区的表达差异。结果两组大鼠在旷场行为测试中,穿行方格的次数差异没有显著性(t=0.632,P>0.05),而在新物体识别测试中,实验组大鼠的1h和24h的成绩差异有显著性(t=-2.37,P<0.05;t=-2.13,P<0.05),实验组大鼠的偏好系数(59.61±9.61)%,(62.72±14.12)%显著高于对照组的(50.46±9.34)%,(52.39±9.16)%。同时,实验组大鼠海马即刻早期基因Arc的表达也高于对照组(t=-5.77,P<0.01)。免疫荧光结果显示在海马的DG区,CA1区,丰富环境组的表达均高于对照组。结论断乳前丰富环境能增加海马即刻早期基因Arc的表达,并且促进大鼠长时记忆。

Objective To investigate the effects of preweaning enrichment on the expression of activity-regulated eytoskeletal protein （Are）, an immediate early gene, and on the long-term memory in rats. Methods Forty neonatal Sprague-Dawley rats were randomly assigned to control group （ standard environment, n = 20 ） and experimental group （enriched environment, n =20）. The experimental group received enriched environment exposure from postnatal day 10 until weaning （2 weeks, 20 minutes per day）. The open field and novel object recognition tests were performed at postnatal day 28. Are expression was detected by Western blotting and immunohistoehemistry, Results There was no significant difference in the open field test between the two groups. However, in the novel object recognition test, the experimental group rats performed significantly better than the control rats after 1 and 24-hr retention. The preference index in the experimental group after 1-hr （59.61% ± 9.61% vs 50.46% ± 9.34% ; P 〈 0.05 ） and 24-hr retention （62.72% ± 14.12% vs 52.39% ±9.16% ; P〈0.05 ） was＇significantly higher than that in the control group. Are expression in both areas CA1 and DG of hippoeampus in the experimental group increased significantly compared with that in the control group （P 〈 0.01 ）. Conclusions Preweaning enrichment can up-regulate the expression of immediate early gene, Are, in the hippoeampus of the rats, and promote their long-term memory.