抑郁大鼠前额叶皮质S100B蛋白表达和甲基化水平及不同机制抗抑郁剂效果评价

S100B protein expression and methylation level in prefrontal cortex of depressed rats and the effects of antidepressants with different mechanisms

目的探讨慢性不可预见性温和应激模型大鼠前额叶皮质S100B蛋白表达水平和甲基化状态,比较氟西汀及度洛西汀的抗抑郁效果.方法将32只SD大鼠按随机数字表法分为氟西汀组、度洛西汀组、生理盐水组及空白组,每组8只.氟西汀组、度洛西汀组及生理盐水组给予42 d不可预见性温和应激并在第22 d至42 d分别给予氟西汀、度洛西汀及生理盐水干预,空白组不给予任何干预.采用体质量、避暗实验、蔗糖偏好实验进行行为学评估,免疫组化法检测前额叶皮质S100B蛋白表达,甲基化特异性聚合酶链式反应检测前额叶皮质S100B编码基因启动子区CpG岛区甲基化状态.结果造模后及药物干预后4组大鼠避暗潜伏期及蔗糖偏好指数与实验前比较差异均有统计学意义(P<0.05),4组间比较差异均有统计学意义(P<0.05).4组大鼠S100B平均吸光度比较差异有统计学意义(P<0.05),生理盐水组S100B平均吸光度值显著高于其他3组(P<0.05),氟西汀组与度洛西汀组比较差异无统计学意义(P>0.05),空白组S100B平均吸光度值显著低于其他3组(P<0.05).S100B蛋白编码基因启动子区CpG岛甲基化条带在各组大鼠前额叶皮质均显示为非甲基化状态.结论不可预见性温和应激模型大鼠前额叶皮质S100B蛋白表达升高,且抗抑郁剂能逆转这种高表达,但不同机制抗抑郁剂对其作用差别不大.大鼠前额叶皮质S100B并未显示出非甲基化状态,而抗抑郁剂不能改变这种状态,可能抑郁症的发病及治疗与大鼠前额叶皮质S100B甲基化无关.

Objective To investigate the S100B protein expression and methylation status of chronic un-predictable mild stress(CUMS)rats,and compare the antidepressant effects of fluoxetine and duloxetine.Methods 32 SD rats were randomly divided into fluoxetine group,duloxetine group,saline group and control group,8 cases in each group.The fluoxetine group,duloxetine group and saline group were given 42 d CUMS.Fluoxetine,duloxetine and saline were given on the 22nd to 42nd days respectively.Blank group was not given any intervention.The body mass,step-through task,sucrose preference experiment were used for behavioral evaluation,and immunohistochemistry was used to detect S100B protein expres-sion in prefrontal cortex.The methylation status of the CpG island region in the promoter region of the pre-frontal cortex S100B encoding gene was tested by methylation special PCR.Results After model es-tablishment and drug intervention,the dark-avoidance latency and sucrose preference index of the four groups were significantly different from those before the experiment(P<0.05).The differences among the 4 groups were statistically significant(P<0.05).The mean absorbance of S100B in the 4 groups of rats was statistically significant(P<0.05).The average absorbance of S100B in the saline group was significantly higher than that in the other 3 groups(P<0.05).There was no significant difference be-tween the fluoxetine group and the duloxetine group(P>0.05).The average absorbance value of S 100B in the blank group was significantly lower than the other three groups(P<0.05).The CpG island methylation band of the promoter region of the S100B protein-encoding gene was shown to be unmethylated in the prefrontal cortex of each group.Conclusions The expression of S100B protein in the prefrontal cortex of CUMS rats is elevated,and antidepressants can reverse this high expression.Different mechanisms have little effect on the effects of antidepressants.S100B in the prefrontal cortex of CUMS rats shows no meth-ylation status,and antidepressants cannot change this state.It is possible that the onset and treatment of depression are not associated with S100B methylation in the prefrontal cortex of rats.