免疫激活对精神分裂模型大鼠前额皮质中突触结构和DISC1基因表达的影响

Effects of immune activation on synaptic structure and DISC1 gene expression in cortex of rat with schizophrenia

目的研究脂多糖(LPS)诱导的免疫系统活化对精神分裂模型大鼠前额皮质中突触结构和精神分裂症破坏蛋白1(DISC1)基因表达的影响。方法将40只大鼠随机分为4组,分别为PBS组、PBS+MK-801组、LPS组、LPS+MK-801组。取LPS组与LPS+MK-801组大鼠,腹腔注射LPS溶液(0.2 mg/kg,1周2次),PBS组与PBS+MK-801组注射等剂量PBS溶液,共6次。第3次注射时,取PBS+MK-801组与LPS+MK-801组大鼠,腹腔注射MK-801溶液(0.5 mg/kg,1周2次),PBS组与LPS组注射等剂量生理盐水,共4次。最后1次注射后2 h,对各组大鼠进行摇头行为评估与旷场实验检测;将大鼠处死,取其脑组织备测;运用RT-qPCR、高尔基染色、免疫组化和ELISA试剂盒分别检测前额皮质中DISC1基因表达、树突棘状态、小胶质细胞活化与炎性细胞因子含量。结果与PBS组比较,PBS+MK-801组大鼠DISC1基因表达升高(P<0.01),摇头评分增加(P<0.01),旷场位移距离增加(P<0.0001);与LPS组比较,LPS+MK-801组大鼠DISC1基因表达,摇头评分与旷场位移距离都明显增加(P<0.0001);与PBS+MK-801组比较,LPS+MK-801组大鼠DISC1基因表达,摇头评分与旷场位移距离进一步增加(P<0.0001)。与此同时,与PBS组和PBS+MK-801组比较,LPS组与LPS+MK-801组大鼠前额皮质中iba1蛋白含量明显增加(P<0.05),炎性细胞因子含量明显提高(P<0.05),树突棘长度与密度明显降低(P<0.05)。结论LPS诱发的免疫系统活化能够增加精神分裂模型易感性,其可能的机制是协同MK-801提高DISC1基因表达,最终导致大鼠精神行为异常。

Objective To study the effect of lipopolysaccharide(LPS)-induced immune system activation on synaptic structure and DISC1 gene expression in the cortex of rats with schizophrenia.Methods 40 rats were divided into 4 groups,which were PBS group,PBS+MK-801 group,LPS group and LPS+MK-801 group.The rats in LPS group and LPS+MK-801 group were administrated with LPS solution(0.2 mg/kg,i.p.BIW)for 6 times in total,the rats in PBS group and PBS+MK801 group were administrated with PBS.At the third time when the rats were administrated with LPS solution,the rats in PBS+MK-801 group and LPS+MK-801 group were administrated with MK-801 solution(0.5 mg/kg,i.p.BIW)for a total of 4 times,the rats in PBS group and LPS group were administrated with saline.The head shaking and the open field tests were then evaluated in the rats.Immediately,the rats were sacrificed,and their brain were saved for testing.RT-qPCR,Golgi staining,immunohistochemistry and ELISA kits were used to detect DISC1 gene expression,dendritic spine status,microglia activation and inflammatory cytokine content in cortex,respectively.Results Compared with the PBS group,the expression of DISC1 gene of the rats in the PBS+MK-801 group increased(P<0.01),the score of head shaking increased(P<0.01),and the distance of the open field increased(P<0.0001);As well as the LPS+MK-801 group,compared with the LPS group,the expression of DISC1 gene increased(P<0.0001),the head shaking score and the distance of the open field increased(P<0.0001).In addition,compared with the PBS+MK-801 group,the expression of DISC1 gene,the shaking head score and the open field distance of the LPS+MK-801 group further improved(P<0.0001).Furthermore,compared with PBS group and PBS+MK-801 group,the content of iba1 in the cortex of LPS group and LPS+MK-801 group significantly increased(P<0.05),the content of inflammatory cytokines significantly increased(P<0.05),and the length and density of dendritic spines significantly decreased(P<0.05).Conclusion The activation of the immune system induced by LPS can contribute to the susceptibility of schizophrenia model,and the possible mechanism is that it cooperates with MK-801 to increase the expression of DISC1 gene,which ultimately leads to abnormal mental behavior in rats.