长期慢性温和应激对大鼠抑郁样行为及热休克蛋白70的影响

Effect of long-term chronic mild stress on depression-like behavior and the expression of heat shock pro-tein 70 in rats

目的探讨不同时间长度慢性温和应激对大鼠抑郁样行为的影响，及其对热休克蛋白70的影响。方法将标准鼠龄SD雄性大鼠分为两组，一组接受3周的慢性温和应激，为短期组（n=6）。另一组接受6周的慢性温和应激，为长期组（n=5）。慢性温和应激前后分别进行糖水偏好实验与敞箱实验，检测大鼠的抑郁样行为。慢性温和应激结束后分别利用Western—Blot、RT—PCR、免疫组化的方法检测大鼠海马与额叶的热休克蛋白70（HSP70）水平。结果长期组慢性温和应激后糖水偏好程度、水平运动指数、中央格停留时间均高于短期组（P〈0．05）；Western-Blot检测显示长期组海马与额叶的HSP70（相对光密度值分别为0．81±0．08，0．85±0．08）均高于短期组（0．60±0．06，0．85±0．07）（P〈0．05）；RT—PCR检测显示长期组海马的HSP70（0．90±0．05，1．37±0．38）高于短期组（0．78-4-0．04，1．08±0．14）（P〈0．05）；免疫组化显示长期组的HSP70在海马与额叶也高于短期组（P〈0．05）。结论长期慢性温和应激较短期慢性温和应激，大鼠的抑郁症状明显减少，同时伴随的是长期应激大鼠脑的HSP70增加。

Objective To explore the effect of long-term chronic mild stress on depression-like behaviors and the expression of heat shock protein 70 （HSP70） in rats. Methods The standard SD rats were divided into two groups as following：one group （ n = 6）was treated with chronic mild stress for 3 weeks, and another group （ n = 5 ） was treated with chronic mild stress for 6 weeks. Depression-like behaviors of rats was observed by sucrose con- sumption test and open field test before and after chronic mild stress. And Western Blot, RT-PCR and immunohis- tochemistry were utilized to detect the HSP70 expression in the hippocampus and frontal lobes of rats after chronic mild stress. Results The sucrose favoritism in sucrose consumption test, the scores of crossing and the time for rats＇ retention in the center grid of open field test in long-term group were higher than those in short term group（P 〈0.05）. HSP70 expression in the hippocampus and frontal lobes of long-term group（0.81 ±0.08,0.85 ±0.08） detected by Western Blot and immunohistochemistry was higher that of short-term group （0.60 ± 0.06,0.85 ± 0.07 ）. HSP70 expression in the hippocampus of long-term group （0.90 ± 0.05,1.37 ± 0.38 ） detected by RT-PCR was higher that of short-term group （ 0.78 ± 0.04,1.08 ± 0.14 ） （P 〈 0.05 ）. Conclusion After long-term chronic mild stress, the depression-like behaviors decrease, and at the same time HSP70 mRNA and protein increase.