氟西汀对慢性不可预见应激模型大鼠海马脂质的影响

Effects of fluoxetine on lipidomics of hippocampal tissue in chronic unpredictable stress model rats

目的探讨氟西汀(fluoxetine,Flx)对慢性不可预见应激抑郁(chronic unpredictable stress,CUS)模型大鼠海马脂质的影响。方法30只Sprague-Dawley大鼠按随机数字表法随机分为Sham组、CUS组和CUS+Flx组,每组10只。CUS组和CUS+Flx组大鼠连续28 d每天接受一至两种随机的刺激,进行CUS造模,随后这两组大鼠分别接受腹腔注射1 ml/kg生理盐水和10 mg/kg氟西汀,每天1次,连续14 d。Sham组大鼠在笼中正常饲养28 d,然后腹腔注射生理盐水(1 ml/kg),每天1次,连续14 d。在最后一次注射后24 h进行糖水偏好实验,随后处死大鼠,分离大鼠海马,通过高效液相色谱-质谱联用技术进行脂质水平检测,采用SIMCA-P 14.1和LipidSearch software version 4.1软件进行脂质相对含量分析。运用SPSS 19.0进行统计分析。运用单因素方差分析或Kruskal-Wallis检验进行多组间的比较,Bonferroni进行事后检验。运用Pearson相关或Spearman相关进行大鼠行为学指标和海马脂质分子水平的相关分析。结果3组大鼠糖水偏好实验差异有统计学意义(F=12.830,P<0.001)。其中,CUS组大鼠[(43.57±12.38)%]糖水偏好率明显低于Sham组[(67.09±11.81)%]和CUS+Flx组[(62.74±8.58)%],均差异有统计学意义(均P<0.05)。脂质检测分析显示,三组间存在95个差异性脂质小分子,主要分布于甘油磷脂类和鞘脂类。相关分析发现磷脂酰乙醇胺(phosphatidylethanolamine,PE)类的脂质小分子中PE(34∶1e)+H、PE(18∶1p/20∶1)+H、PE(18∶1/18∶1)+Na、PE(36∶2p)-H、PE(16∶0/20∶4)-H、PE(18∶0/18∶2)-H、PE(16∶0e/22∶6)-H、PE(18∶1/20∶4)-H及鞘脂类的CerG1(d18∶2/24∶0+O)+H与大鼠糖水偏好率呈负相关(r=-0.477,-0.433,-0.603,-0.382,-0.464,-0.482,-0.514,-0.511,-0.490;均P<0.05)。而PE(42∶6p)+Na、PE(34∶0p)-H和鞘脂类SM(d22∶1/16∶0)+HCOO与大鼠糖水偏好率呈正相关(均r=0.379,0.397,0.388;均P<0.05)。结论氟西汀对CUS模型大鼠的抑郁样行为的改善作用可能与其调节海马甘油磷脂及鞘脂类水平有关。

Objective To investigate the effects of fluoxetine(Flx)on lipidomics of hippocampal tissue in chronic unpredictable stress(CUS)model rats.Methods A total of 30 Sprague-Dawley rats were randomly divided into Sham group,CUS group and CUS+Flx group,with 10 rats in each group.Rats in the CUS group and CUS+Flx group were received one or two random stimuli every day for 28 days,and then they were received intraperitoneal injection of normal saline(1 ml/kg)and fluoxetine(10 mg/kg)respectively once a day for 14 days.Rats in the Sham group were maintained in their home cages for 28 days,and then received intraperitoneal injection of saline(1 ml/kg)once a day for 14 days.The sugar water preference experiment was carried out 24 hours after the last injection,and then the rats were killed to separate the rat hippocampus.The levels of lipid composition in hippocampus were detected by high performance liquid chromatography-mass spectrometry.The relative content of lipid was analyzed by Simca-p 14.1 and LipidSearch software version 4.1.SPSS 19.0 was used for statistical analysis.One-way ANOVA or Kruskal-Wallis test was used for comparison among groups,and Bonferroni test was used for post-hoc test.Pearson correlation or Spearman correlation was used to analyze the correlation between behavioral indexes and lipid molecular level in hippocampus.Results There was significant difference in sugar preference test among the three groups(F=12.830,P<0.001).The percentage of sucrose intake of rats in CUS group((43.57±12.38)%)was significantly lower than those in Sham group((67.09±11.81)%)and CUS+Flx group((62.74±8.58)%)(both P<0.05).Ninety five differential lipid molecules were screened among the three groups by lipidomic analysis,mainly distributed in glycerophospholipids and sphingolipids.Among them,levels of PE(34∶1e)+H(r=-0.477),PE(18∶1p/20∶1)+H(r=-0.433),PE(18∶1/18∶1)+Na(r=-0.603),PE(36∶2p)-H(r=-0.382),PE(16∶0/20∶4)-H(r=-0.464),PE(18∶0/18.2)-H(r=-0.482),PE(16∶0e/22∶6)-H(r=-0.514),PE(18∶1/20∶4)-H(r=-0.511)and CerG1(d18∶2/24∶0+O)+H(r=-0.490)were negatively correlated with sucrose preference rate(all P<0.05),whereas levels of PE(42∶6p)+Na(r=0.379),PE(34∶0p)-H(r=0.397)and SM(d22∶1/16.0)+HCOO(r=0.388)were positively correlated with sucrose preference rate(all P<0.05).Conclusion Flx improves the depressive-like behavior of CUS model rats,which may be related to the regulation of hippocampal glycerophospholipid and sphingolipid metabolism.