妊娠期慢性应激致子代小鼠杏仁核神经元损伤和抑郁样行为

Neuron injury of amygdala and depression-like behavior in offspring mice induced by chronic pregnancy stress

目的探究妊娠期慢性应激对仔鼠青春期抑郁样行为影响的性别差异,以及杏仁核是否参与介导仔鼠抑郁样行为及其可能机制。方法采用C57BL/6J小鼠,雌雄合笼,将孕鼠随机分为正常对照(CON)组和妊娠期慢性应激(CPS)组,孕鼠分娩当天为产后第0天(PND0),将CON组和CPS组的仔鼠进一步分成雌性(Female)组、雄性(Male)组。在PND35,开始测试仔鼠抑郁样行为,Golgi-Cox染色观察基底外侧杏仁核(BLA)锥体神经元形态,TUNEL检测BLA神经元凋亡情况,ELISA检测仔鼠血清促肾上腺激素释放激素(CRH)含量,Western blot技术检测杏仁核哺乳动物雷帕霉素靶蛋白(mTOR)和磷酸化mTOR[p-mTOR(Ser2448)]表达水平。结果妊娠期慢性应激导致仔鼠出现抑郁样行为,其与性别间存在交互作用。在强迫游泳实验中,CPS组子代雌鼠、雄鼠的不动时间均增加(P<0.05,P<0.001),且雄鼠较雌鼠表现出更为严重的绝望行为(P<0.05),糖水偏好测试中,相较于CON组,CPS组的子代雌鼠糖水偏好率降低(P<0.05),子代雄鼠也有下降的趋势,但差异无统计学意义。相较于CON组,CPS组的雌性和雄性仔鼠BLA区域的神经元树突分支密度降低(P<0.01)、神经元凋亡程度增加(P<0.001),CPS组的雌雄仔鼠的杏仁核p-mTOR表达水平均显著降低(P<0.001)。妊娠期慢性应激导致仔鼠血清CRH含量升高(P<0.001),且CPS组雌性仔鼠的血清CRH水平高于雄性仔鼠(P<0.05)。结论妊娠期慢性应激导致子代青春期小鼠出现抑郁样行为并存在性别差异,且妊娠期慢性应激导致仔鼠BLA神经元的树突萎缩和凋亡,其作用机制可能是仔鼠杏仁核m-TOR的激活受到抑制,CRH可能参与介导妊娠期慢性应激致仔鼠抑郁样行为的性别差异和BLA神经元损伤。

Objective To investigate the sex difference of the effects of chronic pregnancy stress on depression-like behavior in offspring adolescent mice and whether the amygdala is involved in mediating depression-like behavior and its possible mechanism.Methods Male and female of C57BL/6J mice were put in cage together.Pregnant mice were randomly divided into normal control group(CON group)and chronic pregnancy stress group(CPS group).The day of delivery was recorded as post-natal day(PND0).The offspring of different groups were divided into Female group and Male groupaccording to sex,respectively.From PND35,the depressive-like behavior of offspring was monitored in different groups.Morphological structure of basolateral amygdala(BLA)cone neurone was observed by Golgi-Cox staining,and apoptosis of BLA neurone was detected by TUNEL.Serum corticotrophin-releasing hormone(CRH)was detected by ELISA.The level of protein associated with amygdala mammalian target of rapamycin(mTOR)and phosphorylated mammalian target of rapamycin[p-mTOR(Ser2448)]was detected by Western blot.Results Depression-like behavior was appeared in different sexual offspring by chronic pregnancy stress,and there was an interaction between chronic pregnancy stress and gender.In the forced swimming test,the immobility time of offspring in the CPS group prominently increased(Female:P<0.05,Male:P<0.001).Interestingly,compared with female offspring,despairing behavior of male offspring was much more clearly observed in CPS group(P<0.05).Compared with offspring of CON group,the rate of sucrose preference was significantly reduced in the female offspring of CPS group(P<0.05),while no obvious difference was observed in the male offspring.Compared with the CON group,the density of neuronal dendrite branches in the BLA of offspring mice in the CPS group decreased(Female:P<0.01,Male:P<0.01)and the degree of neuronal apoptosis increased(Female:P<0.001,Male:P<0.001),the expression level of p-mTOR in amygdala of offspring mice in CPS group significantly decreased(Female:P<0.001,Male:P<0.001).Chronic pregnancy stress increased the serum CRH level of offspring mice(P<0.001),and the gender had significant influence on serum CRH level,the serum CRH level of female in CPS group was higher than that of male(P<0.05).Conclusion Chronic pregnancy stress leads to depression-like behavior in offspring adolescent mice,and the depression-like behavior has gender differences.In addition,chronic pregnancy stress leads to dendrite atrophy and apoptosis of BLA neurons in offspring mice,and the mechanism may be that the activation of mTOR in the amygdala of offspring mice is inhibited.CRH may be involved in mediating sex differences in depression-like behavior and BLA neuron damage in offspring induced by chronic pregnancy stress.