文拉法辛对小鼠抑郁样行为及前额叶皮层中髓鞘损伤和Nrg1Ⅲ-ErbB2表达的影响

Effects of venlafaxine on depression-like behavior and myelin damage and expression of Nrg1 Ⅲ-ErbB2 of prefrontal cortex in cuprizone-treated mice

目的 探讨文拉法辛对双环己酮草酰二腙(CPZ)所致的小鼠抑郁样行为及前额叶皮层(PFC)中环腺苷酸-磷酸二酯酶(CNPase)、髓鞘碱性蛋白(MBP)以及Nrg1Ⅲ-ErbB2表达的影响。方法 将32只8周龄C57BL/6雄性小鼠随机分为对照组、文拉法辛组、CPZ组和文拉法辛+CPZ组。CPZ组和CPZ+文拉法辛组均饲喂含0.2%的CPZ饲料5周以构建CPZ模型,文拉法辛组及文拉法辛+CPZ组经由灌胃接受20 mg/(kg·d)的文拉法辛治疗5周,对照组和CPZ组在同一时间段每天灌胃生理盐水200μl。5周干预结束后进行旷场实验、糖水偏好实验、悬尾实验,随后立即处死每组的5只小鼠,收集PFC组织于液氮中,采用Western blot法检测PFC中的CNPase、MBP表达变化,采用反转录-聚合酶链反应检测Nrg1Ⅲ-ErbB2 mRNA信号的表达水平。每组剩余3只小鼠灌注多聚甲醛固定液后通过免疫荧光染色CNPase观察少突胶质细胞的数量变化。结果 CPZ组小鼠的旷场运动总距离和中心运动距离比低于对照组[(12.50±4.73)m比(25.63±5.64)m、(5.92±1.98)%比(11.78±4.17)%],悬尾不动时间长于对照组[(153.75±26.4)s比(71.62±20.95)s],糖水偏好指数低于对照组[(79.16±6.53)%比(92.67±2.97)%],PFC中的CNPase和MBP蛋白表达低于对照组[(0.56±0.08)比(0.85±0.13)、(0.37±0.05)比(1.01±0.08)],Nrg1Ⅲ和ErbB2的mRNA表达低于对照组[(1.06±0.16)比(0.38±0.27)、(1.01±0.01)比(0.42±0.41)],差异均有统计学意义(均P<0.05)。CPZ+文拉法辛组小鼠的旷场运动总距离和中心运动距离比高于CPZ组[(22.64±6.59)m比(12.50±4.73)m、(10.6±2.85)%比(5.92±1.98)%],悬尾不动时间少于CPZ组[(109.25±35.69)s比(153.75±26.4)s],糖水偏好指数高于CPZ组[(91.63±2.98)%比(79.16±6.53)%],PFC中的CNPase和MBP蛋白表达高于CPZ组[(0.84±0.09)比(0.56±0.08)、(0.71±0.13)比(0.37±0.05)],Nrg1Ⅲ和ErbB2的mRNA表达高于CPZ组[(0.70±0.33)比(0.38±0.27)、(0.80±0.25)比(0.42±0.41)],差异均有统计学意义(均P<0.05)。CNPase免疫荧光染色结果显示,CPZ组小鼠PFC中的CNPase少突胶质细胞少于对照组和CPZ+文拉法辛组。结论 文拉法辛能够上调CPZ小鼠PFC中的CNPase、MBP蛋白表达水平以及Nrg1Ⅲ和ErbB2的mRNA表达水平,增加少突胶质细胞数量,缓解其抑郁样行为。

Objective To investigate the effect of venlafaxine on the depression-like behavior,and the expression of CNPase,MBP and Nrg1Ⅲ-ErbB2 expression in prefrontal cortex(PFC)of cuprizone(CPZ)treated mice.Methods A total of 32 C57BL/6 male mice aged 8-weeks were randomly divided into control group,venlafaxine(Ven)group,model(CPZ)group and CPZ+Ven group.Mice in CPZ and CPZ+Ven groups were fed with diet containing 0.2%CPZ for 5 weeks to establish CPZ model.Ven and CPZ+Ven groups received 20 mg/(kg·d)venlafaxine by gavage for 5 weeks.Control group and CPZ group were gavaged with 200μl saline every day during the same time period.Open field experiment,sugar-water preference experiment and tail suspension experiment were carried out after 5-week intervention,and then 5 mice in each group were killed immediately.PFC was collected in liquid nitrogen.The protein levels of CNPase and MBP in PFC were detected by Western blot,and the level of Nrg1Ⅲ-ErbB2 mRNA was detected by RT-PCR.The remaining mice(n=3)were perfused and fixed with 4%PFA,and then the morphological changes of oligodendrocytes were observed by immunofluorescence staining for CNPase.Results The total distance traveled in open field and distance of central movement of CPZ group were shorter than those of the control group[(12.50±4.73)m vs(25.63±5.64)m,(5.92±1.98)%vs(11.78±4.17)%].The immobility time of suspended tail test was longer than that of the control group[(153.75±26.4)s vs(71.62±20.95)s].Sugar preference index was lower than that of the control group[(79.16±6.53)%vs(92.67±2.97)%].The protein expression levels of CNPase and MBP in PFC were lower than those of the control group[(0.56±0.08)vs(0.85±0.13),(0.37±0.05)vs(1.01±0.08)].The mRNA levels of Nrg1Ⅲand ErbB2 were lower than those of the control group[(0.38±0.27)vs(1.06±0.16),(0.42±0.41)vs(1.01±0.01)].The differences of all the above were statistically significant(P<0.05).The total distance traveled in open field and distance of central movement of CPZ+Ven group were longer than those of the CPZ group[(22.64±6.59)m vs(12.50±4.73)m,(10.6±2.85)%vs(5.92±1.98)%].The immobility time of suspended tail test was longer than that of the CPZ group[(109.25±35.69)s vs(153.75±26.4)s].Sugar preference index was lower than that of the CPZ group[(91.63±2.98)%vs(79.16±6.53)%].The protein expression levels of CNPase and MBP in PFC were lower than those of the CPZ group[(0.84±0.09)vs(0.56±0.08),(0.71±0.13)vs(0.37±0.05)].The mRNA levels of Nrg1Ⅲand ErbB2 were lower than those of the CPZ group[(0.70±0.33)vs(0.38±0.27),(0.80±0.25)vs(0.42±0.41)].The differences of all the above were statistically significant(P<0.05).CNPase immunofluorescence staining showed that there were fewer CNPase oligodendrocytes in the PFC of mice in the CPZ group than in the control group and the CPZ+Ven group.Conclusions Venlafaxine can up-regulate the levels of CNPase and MBP protein and the mRNA levels of Nrg1Ⅲand ErbB2 in the PFC of CPZ mice,increase the number of oligodendrocytes,and alleviate depressionlike behaviors.