丰富环境对慢性脑低灌注大鼠甲状腺激素及其受体的影响
Effect of environmental enrichment on thyroid hormone and thyroid hormone receptor in chronic cerebral hypoperfusion rats
目的 观察慢性脑低灌注大鼠学习记忆能力和甲状腺激素及其受体的变化,以及丰富环境干预的影响.方法 采用随机数字表法将48只大鼠分为4组,每组12只:假手术+标准环境( sham+ SE)组、双血管结扎手术+标准环境(2-VO+ SE)组、假手术+丰富环境(sham+ EE)组和双血管结扎手术+丰富环境( 2-VO+ EE)组.采用Morris水迷宫、放射免疫法、免疫组织化学染色和Western blot方法分别检测大鼠的学习记忆能力、血清甲状腺激素水平以及海马甲状腺激素受体(thyroid hormone receptor α1,TRα1)水平.结果 Morris水迷宫结果显示2-VO+ SE组大鼠在训练的第2、4和5天找到平台的时间显著多于sham+ SE组(t=2.67、2.67和3.18,P<0.05、0.05和0.01),而2-VO+ EE组大鼠在第4和5天找到平台的时间显著少于2-VO+ SE组(t=4.08和3.55,均P<0.01);2-VO+ SE组大鼠在目标象限花费的时间显著低于sham+ SE组(t=3.33,P<0.05),而2-VO+ EE组大鼠在目标象限花费的时间显著多于2-VO+ SE组(t=4.46,P<0.01).放射免疫检测结果显示,与sham+ SE组(0.60±0.15)比较,2-VO+ SE组(0.40±0.04)大鼠血清三碘甲状腺原氨酸(T3)的水平降低;而与2-VO+ SE组比较,2-VO+ EE组(0.66±0.08)大鼠血清T3的水平明显增加(t =3.62,P<0.01).免疫组织化学结果显示,与sham+ SE组比较,2-VO+ SE组大鼠海马CA1和DG区TRα1积分吸光度值明显降低(t=3.18、3.20,均P<0.05);而与2-VO+ SE组比较,2-VO+ EE 组大鼠海马CA1和DG区TRα1积分吸光度值明显增强(t=3.93、4.12,均P<0.01).Western blot结果显示,与sham+ SE组比较,2-VO+ SE组大鼠海马TRα1定量分析相对吸光度值明显下降(t=4.35,P<0.05);而与2-VO+ SE组比较,2-VO+ EE组大鼠海马TRα1定量分析相对吸光度值明显增强(t=6.20,P<0.01).结论 慢性脑低灌注可以损害海马相关的学习记忆,而丰富环境干预可以改善慢性脑低灌注引起的学习记忆损害;血清甲状腺激素T3和海马TRα1可能参与丰富环境对认知功能损害的改善作用.
更多objective To observe the changes of learning and memory,thyroid hormone and thyroid hormone receptor in chronic cerebral hypoperfusion in rats,as well as the effects of enriched environment.Methods The rats were randomly divided into 4 groups:sham + standard environment group (sham + SE),2-VO + standard environment group (2-VO + SE),sham + enriched environment group (sham + EE) and 2-VO + enriched environment group (2-VO + EE). Morris water maze,radioimmunoassay,immunohistochemistry and Western blotting methods were used to detect changes in learning and memory in rats,serum thyroid hormone levels and hippocampus thyroid hormone receptors levels.Results Morris water maze showed that compared to the control group,the 2-VO + SE rats took more time to find the platform in day 2,4 and 5,the difference was significant (t =2.67,2.67 and 3.18;P < 0.05,P < 0.05 and P < 0.01,respectively) ; and which could be restored by enriched environment in day 4 and 5 ( t =4.08 and 3.55,both P <0.01 ).The time spent in the target quadrant in 2-VO + SE rats was significantly shorter than the sham group ( t =3.33,P < 0.05 );and which could be restored by enriched environment ( t =4.46,P < 0.01 ).Radioimmunoassay test showed serum T3 levels had a decreased trends in 2-VO + SE rats compared the control; and which could be restored by enriched environment ( t =3.62,P <0.01 ).Immunohistochemistry showed that compared to the sham group,the thyroid hormone receptor α1 in hippocampus CA1 and DG areas was significantly lower in 2-VO + SE rats ( t =3.18 and 3.20,both P <0.05 ) ; and which could be restored by enriched environment (t =3.93 and 4.12,both P <0.01 ).Western blotting results indicated that compared to the sham group,the hippocampus TRα1 was significantly lower in 2-VO + SE rats ( t =4.35,P <0.05 ) ; and which could be restored by enriched environment ( t =6.20,P <0.01 ). Conclusion Chronic cerebral hypoperfusion can damage the hippocampus-related learning and memory,and which can be restored by enriched environment; serum T3 and hippocampus TRα1 may be involved in the restorations of enriched environment.
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