小鼠卵巢不同发育时期SDF-1/CXCR4轴的动态变化

目的分析基质细胞衍生因子1(SDF-1)及其受体(CXCR4)在不同发育时期雌性ICR小鼠卵巢组织中的表达及意义。方法选择4周龄、7周龄和10周龄雌性ICR小鼠共30只,根据典型发育时期分为3组:性成熟前期(4周龄)组、性成熟期(7周龄)组及适龄繁殖期(10周龄)组,每组各10只。每组取5只收集卵巢组织,一侧卵巢提取RNA后利用qPCR检测SDF-1和CXCR4 mRNA表达水平;一侧卵巢固定包埋后切片,采用HE染色观察卵巢组织形态并进行各级卵泡计数,采用免疫组化方法观察SDF-1及CXCR4蛋白在小鼠卵巢组织的表达。余下每组5只促排卵后获取卵丘卵母细胞复合物(COCs),分离卵丘颗粒细胞与卵母细胞并提取RNA,利用qPCR分别检测两种细胞中SDF-1和CXCR4的mRNA表达水平。结果3组小鼠中性成熟前期组卵巢SDF-1 mRNA表达量显著高于其他两组(P<0.05),而CXCR4 mRNA表达量显著低于其他两组(P<0.01)。HE染色显示3个发育阶段小鼠卵巢均可见发育正常的各级卵泡;适龄繁殖期组的卵巢总卵泡数目及初级卵泡数量显著高于其余两组(P<0.01),次级卵泡数显著多于性成熟期组(P<0.01)。免疫组化结果表明:SDF-1及CXCR4蛋白在卵巢各级卵泡的颗粒细胞和卵母细胞中都有表达,而在卵泡膜细胞中几乎不表达。COCs的qPCR结果显示:卵母细胞中,性成熟期组SDF-1 mRNA表达水平显著高于性成熟前期组(P<0.05);卵丘颗粒细胞中,适龄繁殖期组SDF-1 mRNA表达水平显著高于其余两组(P<0.01),性成熟前期组CXCR4 mRNA表达水平显著低于其余两组(P<0.05)。结论SDF-1及其受体CXCR4在不同发育阶段小鼠卵巢卵泡中均有表达且表达水平存在显著差异,提示其可能参与调控小鼠卵泡发育和性腺成熟的过程。

Dynamic changes of SDF-1/CXCR4 axis at different developmental stages of mice ovaries

Objective:To explore the expression and significance of stromal cell-derived factor 1(SDF-1)and CXC chemokine receptor(CXCR4)in ovarian tissues of ICR mice at different development stages.Methods:A total of 30 female ICR mice aged 4,7 and 10 weeks were selected.The mice were divided into three groups according to the typical development stages:pre-sexual maturity group(4 weeks),sexual maturity group(7 weeks)and breeding age group(10 weeks),with 10 mice in each group.The mRNA expression of SDF-1 and CXCR4 was detected by qPCR after RNA extraction from unilateral ovarian tissues of 5 mice in each group.The morphology was observed by HE staining,numbers of follicle in different stages was counted.The expressions of SDF-1 and CXCR4 protein in mice ovarian tissue were detected by immunohistochemical method for another side ovary.The cumulus-oocyte complexs(COCs)were obtained after induced ovulation from 5 mice remained in each group.The cumulus granulosa cells were isolated from oocytes,and RNA was extracted.The mRNA expression levels of SDF-1 and CXCR4 were detected by qPCR.Results:The mRNA expression of SDF-1 in pre-sexual maturity group was significantly higher than that in another two groups(P<0.05)and the mRNA expression level of CXCR4 was significantly lower than that in another two groups(P<0.01).HE staining showed that ovarian tissues of mice at the three development stages had the normal follicles in different stages.The total numbers of ovarian follicles and primary follicles in mice ovary at breeding age were significantly higher than that in another two groups(P<0.01).The secondary follicles were significantly increased in breeding age mice than sexually maturity mice(P<0.01).Immunohistochemical analysis showed that SDF-1 and CXCR4 were expressed in granulosa cells and oocytes of ovarian follicles in different stages,and almost no expression in theca cells.The qPCR results of COCs showed that the expression level of SDF-1 mRNA in oocytes in sexual maturity group was significantly higher than that in pre-sexual maturity group(P<0.05).The SDF-1 mRNA expression level in cumulus granulosa cells in breeding age mice was significantly higher than that in the other two groups(P<0.01),and the CXCR4 mRNA expression level in the pre-sexual maturity group was significantly lower than that in the other two groups(P<0.05).Conclusions:SDF-1 and its receptor CXCR4 are expressed in mice ovarian follicles at different developmental stages,suggesting that it may be involved in the process of regulating mice follicle development and gonad maturation.