氟西汀对抑郁大鼠行为及海马组织内应激活化蛋白激酶信号通路的影响

Effects of fluoxetine on behavior and activating protein kinase signaling pathway in depression rats

目的探讨氟西汀对抑郁大鼠行为学表现及海马组织内丝裂原活化蛋白激酶磷酸酶-1(MKP-1)及Jun氨基末端激酶(JNK)通路蛋白表达的影响。方法40只雄性Sprague Dawley大鼠随机分为正常组、抑郁症组、生理盐水组和氟西汀组,每组10只。正常组大鼠不给予任何刺激;抑郁症组、生理盐水组和氟西汀组大鼠给予8周慢性不可预见性应激(CUMS),于CUMS第5~8周,氟西汀组大鼠给予氟西汀(10 mg·kg^-1·d^-1)灌胃,生理盐水组大鼠给予生理盐水(10 mg·kg^-1·d^-1)灌胃;正常组和抑郁症组大鼠不给予任何干预措施。分别于CUMS前(造模前),CUMS 4周后(造模后)、8周后(干预后)评估4组大鼠行为学变化,最后一次行为学评估后处死大鼠,并取海马组织,采用Western blot法检测海马组织内MKP-1、JNK、磷酸化JNK(p-JNK)蛋白表达水平,并计算p-JNK/JNK比值。结果造模前各组大鼠体质量、蔗糖偏好指数、强迫游泳不动时间及旷场实验结果比较差异均无统计学意义(P>0.05)。正常组大鼠造模前后各行为学指标比较差异均无统计学意义(P>0.05);与造模前比较,造模后抑郁症组、生理盐水组、氟西汀组大鼠体质量降低,蔗糖偏好指数下降,强迫游泳不动时间增加,水平运动距离和直立次数减少(P<0.05)。与正常组比较,造模后抑郁症组、生理盐水组、氟西汀组大鼠体质量降低,蔗糖偏好指数下降,强迫游泳不动时间增加,水平运动距离和直立次数减少(P<0.05)。造模后,抑郁症组、生理盐水组、氟西汀组大鼠各种行为学指标比较差异均无统计学意义(P>0.05)。与正常组比较,干预后生理盐水组及抑郁症组大鼠体质量降低,蔗糖偏好指数下降,强迫游泳不动时间增加,水平运动距离和直立次数减少(P<0.05)。干预后,氟西汀组与正常组大鼠各项行为学指标比较差异均无统计学意义(P>0.05),生理盐水组与抑郁症组大鼠各项行为学指标比较差异均无统计学意义(P>0.05)。与生理盐水组和抑郁症组比较,氟西汀组大鼠体质量增加,蔗糖偏好指数上升,强迫游泳不动时间减少,水平运动距离和直立次数增加(P<0.05)。抑郁症组和生理盐水组大鼠海马组织内MKP-1蛋白表达量高于正常组(P<0.05),氟西汀组大鼠海马组织内MKP-1蛋白表达量低于抑郁症组和生理盐水组(P<0.05),氟西汀组与正常组大鼠海马组织内MKP-1蛋白表达量比较差异无统计学意义(P>0.05)。4组大鼠海马组织内p-JNK、JNK蛋白表达量及p-JNK/JNK比值比较差异均无统计学意义(P>0.05)。结论MKP-1改变可能是抑郁症发病的一个重要基因,其影响抑郁症发病的机制可能不是通过JNK信号通路。氟西汀可能通过下调MKP-1表达水平而改善大鼠抑郁状态。

Objective To investigate the effect of fluoxetine on the behavior of depressive rats and the expression of mitogenactivated protein kinase phosphatase-1(MKP-1)and Jun N-terminal kinase(JNK)protein in hippocampus of tissues.Methods Forty male Sprague Dawley rats were randomly divided into normal group,depression group,saline group and fluoxetine group,with 10 rats in each group.The rats in normal group were not given any stimulation.The rats in the depression group,saline group and fluoxetine group were given chronic unpredictable mild stress(CUMS)for 8 weeks to establish the depression model.From the 5 th to 8 th week of CUMS,the rats in the fluoxetine group were given fluoxetine(10 mg·kg^-1·d^-1)by gavage,and the rats in the saline group were given saline(10 mg·kg^-1·d^-1)by gavage,but the rats in the normal group and depression group were not given any intervention.Behavioral changes of all rats were assessed before CUMS(before modeling),4 weeks after CUMS(after modeling)and 8 weeks after CUMS(after intervention).After the last behavioral assessment,the rats were sacrificed and the hippocampus tissues were taken.The expression of MKP-1,JNK and p-JNK protein in hippocampus tissues were detected by Western blot.Results There was no significant difference in the behavioral indicators such as body weight,sucrose preference index,floating time in the forced swimming and each indicator of open field experiment before modeling among the four groups(P>0.05).There was no significant difference in the all behavioral indexes before and after modeling in the normal group(P>0.05).Compared with before modeling,the body weight and sucrose preference index of rats decreased,the floating time in the forced swimming increased,the horizontal movement distance and the number of erection of rats decreased in the depression group,saline group and fluoxetine group after modeling(P<0.05).Compared with the normal group,the body weight and sucrose preference index of rats decreased,the floating time in the forced swimming increased,the horizontal movement distance and the number of erection of rats decreased in the depression group,saline group and fluoxetine group after modeling(P<0.05).There was no significant difference in all behavioral indexes among the depression group,saline group and fluoxetine group after modeling(P>0.05).Compared with the normal group,the body weight and sucrose preference index of rats decreased,the floating time in the forced swimming increased,the horizontal movement distance and the number of erection of rats decreased in the saline group and depression group after intervention(P<0.05);there was no significant difference in all behavioral indexes of rats between the fluoxetine group and normal group after intervention(P>0.05);there was no significant difference in all behavioral indexes of rats between the saline group and depression group after intervention(P>0.05);compared with the saline group and depression group,the body weight and sucrose preference index of rats increased,the floating time in the forced swimming decreased,the horizontal movement distance and the number of erection of rats increased in the fluoxetine group(P<0.05).The expression of MKP-1 protein in the hippocampus of rats in the depression group and saline group was significantly higher than that in the normal group(P<0.05);the expression of MKP-1 protein in the hippocampus of rats in the fluoxetine group was significantly lower than that in the depression group and saline group(P<0.05);there was no significant difference in the expression of MKP-1 protein in the hippocampus of rats between the fluoxetine group and normal group(P>0.05).There was no significant difference in the expression of p-JNK,JNK protein and p-JNK/JNK in the hippocampus of rats among the four groups(P>0.05).Conclusions The change of MKP-1 may be an important cause of depression,and the JNK signaling pathway may not be involved.Fluoxetine may improve depression by down-regulating the expression of MKP-1.