Objective: To investigate the effects of silent information regulator 1 (SIRT1) in amygdala on depression-like behaviors in rats using chronic restraint stress (CRS) as a model of depression.
Methods: Sixty male SD rats were randomly divided into six groups (n=10 per group): control group (Control), chronic restraint stress group (CRS), CRS + fluoxetine-treated group (CRS + FLU), CRS + saline-treated group (CRS + NaCl), CRS + SIRT1-overexpression group (CRS + AAV-SIRT1), and CRS + empty vector group (CRS + AAV-EGFP). Except for the control group, rats from the other groups were exposed to chronic restraint stress for 21 days. After the modeling, rats in fluoxetine-treated group and saline-treated group were, respectively, treated with fluoxetine (10 mg/kg) or saline (10 mg/kg) by gavage every day for 3 weeks; AAV-SIRT1 or AAV-EGFP was, respectively, stereotaxically injected into the amygdala of rats in SIRT1-overexpression group and empty vector group, and the virus was expressed for 3 weeks. Rats in normal control group and CRS model group were not given any drug treatment. The depression-like behaviors of rats in each group were evaluated by sugar preference test (SPT), open field test (OFT) and forced swimming test (FST). SIRT1 expression in amygdala of rats was assessed by using immunoblot blotting. The number of SIRT1-positive cells in amygdala of rats was detected by immunofluorescence technique.
Results: Compared with the normal control group, the level of SIRT1 protein and the number of SIRT1+ cells in amygdala of the CRS-exposed rats were decreased significantly (P＜0.01), and CRS-exposed rats showed a significant decrease in sucrose preference (P＜0.01), less total horizontal distance (P＜0.01) and less time entered the center field (P＜0.01) in the OFT, a significant increase in the immobility time of the FST (P＜0.01). Fluoxetine treatment (P＜0.05, P＜0.01) or SIRT1 overexpression (P＜0.01) partially reversed the down-regulation of SIRT1 protein and SIRT1+ cells in amygdala of CRS-exposed rats and significantly improved the depression-like behaviors of CRS rats.
Conclusion: Fluoxetine treatment partially reversed the down-regulation of SIRT1 level and the number of SIRT1+ in CRS rats, and significantly improved the depression-like behaviors. The antidepressant effect of fluoxetine treatment may be related to the up-regulation of SIRT1 in the amygdala of CRS-exposed rats.
目的: 观察杏仁核沉默信息调节因子1(SIRT1)蛋白对慢性束缚应激(CRS)大鼠抑郁样行为的影响。方法: 60只SD雄性大鼠随机分为6组(n=10):正常对照组(Control)、慢性束缚应激组(CRS)、CRS +氟西汀(FLU)组(CRS + FLU)、CRS +生理盐水组(CRS + NaCl)、CRS + SIRT1过表达组(CRS + AAV-SIRT1)和CRS +空载体组(CRS + AAV-EGFP)。除了正常对照组,其余各组均接受慢性束缚应激造模21 d。造模结束后,氟西汀组和生理盐水组大鼠每天分别灌胃给予氟西汀(10 mg/kg)或生理盐水(10 mg/kg),持续3周;SIRT1过表达组和空载体组大鼠分别脑立体定位,注射腺相关病毒AAV-SIRT1或AAV-EGFP于杏仁核,待病毒表达3周;正常组和抑郁症组大鼠则不给予任何药物。应用糖水偏好实验(SPT)、旷场实验(OFT)和强迫游泳实验(FST)检测各组大鼠的抑郁样行为学变化;蛋白免疫印迹实验检测大鼠杏仁核中SIRT1蛋白的表达;免疫荧光技术检测大鼠杏仁核中SIRT1阳性细胞数量。结果: 与正常对照组相比,CRS抑郁大鼠杏仁核中SIRT1蛋白水平和SIRT1阳性细胞数显著降低(P＜ 0.01),糖水偏好程度明显降低(P＜0.01),旷场实验中运动总距离和中心停留时间显著缩短(P＜0.01),强迫游泳不动时间明显延长(P＜0.01)。氟西汀治疗或SIRT1过表达均可以部分逆转CRS大鼠杏仁核SIRT1蛋白和SIRT1阳性细胞数的下调(P＜0.05, P＜0.01),并且可以显著改善上述抑郁样行为。结论: 氟西汀治疗可以部分逆转CRS大鼠下调的SIRT1蛋白及SIRT1阳性细胞数,同时显著改善抑郁样行为,其抗抑郁疗效可能与CRS大鼠杏仁核中SIRT1蛋白的上调有关。.
Keywords: amygdala; chronic restraint stress; fluoxetine; rats; silent information regulator l.