Micro RNAs(mi RNAs) are dynamically regulated during neurodevelopment,yet few reports have examined their role in spina bifida.In this study,we used an established fetal rat model of spina bifida induced by intragastrically administering olive oil-containing all-trans retinoic acid to dams on day 10 of pregnancy.Dams that received intragastric administration of all-trans retinoic acid-free olive oil served as controls.The mi RNA expression profile in the amniotic fluid of rats at 20 days of pregnancy was analyzed using an mi RNA microarray assay.Compared with that in control fetuses,the expression of mi RNA-9,mi RNA-124 a,and mi RNA-138 was significantly decreased(> 2-fold),whereas the expression of mi RNA-134 was significantly increased(> 4-fold) in the amniotic fluid of rats with fetuses modeling spina bifida.These results were validated using real-time quantitative reverse-transcription polymerase chain reaction.Hierarchical clustering analysis of the microarray data showed that these differentially expressed mi RNAs could distinguish fetuses modeling spina bifida from control fetuses.Our bioinformatics analysis suggested that these differentially expressed mi RNAs were associated with many cytological pathways,including a nervous system development signaling pathway.These findings indicate that further studies are warranted examining the role of mi RNAs through their regulation of a variety of cell functional pathways in the pathogenesis of spina bifida.Such studies may provide novel targets for the early diagnosis and treatment of spina bifida. MicroRNAs (miRNAs) are dynamically regulated during neurodevelopment, yet few reports have examined their role in spina bifida. This study, we used an established fetal rat model of spina bifida induced by intragastrically equipped olive oil-containing all-trans retinoic acid to dams on day 10 of pregnancy. Dams that received intragastric administration of all-trans retinoic acid-free olive oil served as controls. mi RNA expression profile in the amniotic fluid of rats at 20 days of pregnancy was analyzed using an mi RNA microarray assay. Compared with that in control fetuses, the expression of mi RNA-9, mi RNA-124 a, and mi RNA-138 was significantly decreased (> 2-fold) > 4-fold) in the amniotic fluid of rats with fetuses modeling spina bifida. These results were validated using real-time quantitative reverse-transcription polymerase chain reaction. Hierarchical clustering analysis of the microarray data showed that the se differentially expressed mi RNAs could distinguish fetuses modeling spina bifida from control fetuses. Our bioinformatics analysis suggested that these differentially expressed mi RNAs were associated with many cytological pathways, including a nervous system development signaling pathway. These further studies are warranted for examining the role of miRNAs through their regulation of a variety of cell functional pathways in the pathogenesis of spina bifida.Such studies may provide novel targets for the early diagnosis and treatment of spina bifida.