地卓西平诱导精神分裂症模型大鼠海马灰质体积及免疫相关基因的变化

Changes of hippocampal gray matter volume and immune related genes in dizocilpine-induced schizophrenia model rats

目的探讨地卓西平(dizocilpine,MK-801)重复给药建立的精神分裂症模型大鼠的海马灰质体积和候选免疫相关基因表达的变化。方法将出生后28 d的30只SPF级雄性Sprague-Dawley大鼠按照随机数字表法分为MK-801中剂量组(0.25 mg/kg)、MK-801高剂量组(0.50 mg/kg)和生理盐水(5 mL/kg)组,每组10只,大鼠按照分组连续腹腔注射给药14 d,1次/d。大鼠在出生后60 d依次进行旷场实验、新物体识别实验和Y迷宫实验,分别检测自发活动、探索能力、焦虑程度和物体识别记忆能力以及空间工作记忆;在出生后67 d时采用结构磁共振成像检测大鼠海马灰质体积的变化;在出生后70 d采用qRT-PCR检测大鼠海马组织候选免疫相关基因的表达。采用SPSS 25.0进行统计分析,多组间比较采用单因素方差分析,进一步两两比较采用Tukey检验。结果(1)行为学结果表明,3组大鼠的运动总距离、中央区域活动时间、新物体识别指数、自发正确交替率均差异有统计学意义(F=11.15,10.11,13.62,11.99,均P<0.05)。MK-801中剂量组和MK-801高剂量组大鼠的运动总距离[(21.44±2.17)m,(22.87±1.96)m]均高于生理盐水组[(18.70±1.88)m](均P<0.05),中央区域活动的时间[(3.24±1.58)s,(2.50±1.32)s]均低于生理盐水组[(6.05±2.48)s](均P<0.01),新物体识别指数[(56.10±3.99)%,(54.00±6.41)%]均低于生理盐水组[(65.90±5.65)%](均P<0.01),自发正确交替率[(54.60±7.03)%,(51.60±8.84)%]均低于生理盐水组[(68.40±8.57)%](均P<0.01)。(2)结构磁共振成像结果表明,3组大鼠海马灰质体积差异有统计学意义(F=9.24,P<0.001)。MK-801中剂量组和MK-801高剂量组大鼠的海马灰质体积均低于生理盐水组(均P<0.05)。(3)通过构建蛋白-蛋白相互作用网络筛选出4个候选免疫相关的基因:神经肽Y、生长抑素、胆囊收缩素和速激肽1。qRT-PCR结果发现3组大鼠海马神经肽Y、生长抑素和胆囊收缩素的mRNA表达水平均差异有统计学意义(F=11.41,10.43,5.85,均P<0.05),3组间速激肽1 mRNA表达水平差异无统计学意义(F=0.08,P>0.05)。MK-801高剂量组大鼠海马神经肽Y、生长抑素和胆囊收缩素的mRNA水平均低于生理盐水组(均P<0.05)。结论中剂量和高剂量MK-801给药均可导致大鼠海马灰质体积减小,但二者对海马免疫相关基因的表达具有不同的影响,其中高剂量给药造成的影响更大。

Objective To investigate the changes of hippocampal gray matter volume and expression of candidate immune related genes in a rat model of schizophrenia established by repeated administration of dizocilpine(MK-801).Methods Thirty SPF grade Sprague-Dawley male rats at postnatal day 28 were randomly divided into MK-801 medium-dose(0.25 mg/kg)group,MK-801 high-dose(0.50 mg/kg)group and normal saline(5 mL/kg)group according to random number table method,with 10 in each group.Rats were given continuous intraperitoneal administration according to grouping once a day for 14 days.Open field test,novel object recognition test and Y-maze test were used at postnatal day 60 to detect spontaneous activity,exploration ability,anxiety level,object recognition memory ability and spatial working memory of rats,respectively.At postnatal day 67,structural magnetic resonance imaging was used to detect the changes of hippocampal gray matter volume in rat.And at postnatal day 70,qRT-PCR was used to detect the expression of candidate immune-related genes in rat hippocampus.SPSS 25.0 was used for statistical analysis,one-way ANOVA was used for comparison among multiple groups,and Tukey test was used for further pairwise comparisons.Results(1)The behavioral results showed that there were significant differences in the total movement distance,central area activity time,novel object recognition index,and spontaneous correct alternation rate among the three groups(F=11.15,10.11,13.62,11.99,all P<0.05).The total movement distances in MK-801 medium-dose group and MK-801 high-dose group((21.44±2.17)m,(22.87±1.96)m)were higher than that in the normal saline group((18.70±1.88)m)(both P<0.05).The activity time of the central area in the MK-801 medium-dose group and MK-801 high-dose group((3.24±1.58)s,(2.50±1.32)s)were lower than that of the normal saline group((6.05±2.48)s)(both P<0.01).Novel object recognition indexes in the MK-801 medium-dose group and MK-801 high-dose group((56.10±3.99)%,(54.00±6.41)%)were both lower than that in the normal saline group((65.90±5.65)%)(both P<0.01),and the rates of spontaneous correct alternation((54.60±7.03)%,(51.60±8.84)%)in the two groups were lower than that of the normal saline group((68.40±8.57)%)(both P<0.01).(2)The results of structural magnetic resonance imaging showed that there were significant differences in the volume of hippocampal gray matter among the three groups(F=9.24,P<0.001).The volumes of hippocampal gray matter in MK-801 medium-dose group and MK-801 high-dose group were lower than that in normal saline group(both P<0.001).(3)By constructing protein-protein interaction network,four candidate immune related genes were screened out:neuropeptide Y(NPY),somatostatin(SST),cholecystokinin(CCK)and tachykinin 1(TAC1).The results showed that the mRNA expression levels of NPY,SST and CCK in the hippocampus of the three groups were significantly different(F=11.41,10.43,5.85,all P<0.05),but there was no statistical difference in the TAC1 mRNA expression level(F=0.08,P>0.05).The mRNA levels of NPY,SST and CCK in the hippocampus of rats in the MK-801 high-dose group were lower than those in the normal saline group(all P<0.05).Conclusion Both medium dose and high dose MK-801 administration can reduce the volume of hippocampal gray matter in schizophrenia model rats,but they have different effects on the expression of hippocampal immune related genes,of which high dose administration has a greater effect.