目的：该研究利用叶酸拮抗剂甲氨喋呤（MTX）构建叶酸生物学活性受抑制的斑马鱼模型后，观察叶酸生物学活性受抑后对斑马鱼心脏发育的干扰作用以及对斑马鱼心脏发育相关基因BMP2b及HAS2表达的影响。 方法：用不同浓度的MTX处理不同发育时段的斑马鱼胚胎，于48 hpf（hours post fertilization）观察胚胎心脏发育情况并计数各组心脏发育异常个体的百分比及心率，评定MTX 对斑马鱼心脏发育的影响程度。用1.5×10-3 M的MTX处理6~10 hpf 发育时段的斑马鱼胚胎作为MTX处理组。于24 hpf及48 hpf 在显微镜下观察MTX处理组斑马鱼胚胎心脏发育情况。借助胚胎整体原位杂交和Real-time PCR 的方法检测BMP2b和HAS2在正常对照组及MTX处理组胚胎的表达水平。结果：胚胎早期发育阶段6~12hpf是斑马鱼胚胎对MTX的敏感时期。显微镜下观察结果显示MTX处理组斑马鱼心脏发育延迟，并有心脏形态发育明显异常。胚胎整体原位杂交结果显示MTX处理组斑马鱼心脏发育相关基因BMP2b及HAS2在心脏的表达于36 hpf及48 hpf下调。Real-time PCR 结果显示MTX处理组斑马鱼BMP2b的相对表达量在12，24，36及48 hpf减少，HAS2的相对表达量在24，36及48 hpf减少。结论：叶酸生物学活性受抑对早期胚胎的心脏发育影响较大，可导致斑马鱼心脏发育延迟及心脏形态异常，并下调斑马鱼心脏发育相关基因BMP2b及HAS2的表达，这可能是叶酸生物学活性受抑后导致心脏发育异常的机制之一。［中国当代儿科杂志，2007，9（2）：159-163］

OBJECTIVE: To study the effect of methotrexate (MTX), a folic acid antagonist which can lead to folic acid deficient, on the cardiac development and on the expressions of BMP2b and HAS2 in zebrafish. METHODS: The zebrafish embryos at 6-48 hrs post fertilization (hpf) were treated with various concentrations of MTX (0.5×10-3 , 1.0 ×10-3 and 2.0×10-3 M). At 48 hpf, the percentage of cardiac malformation and heart rate were recorded. The zebrafish embryos at 6-10 hpf treated with 1.5×10-3 M MTX were used as the MTX treatment group. At 24 and 48 hpf the cardiac morphology was observed under a microscope. The expressions of BMP2b and HAS2 in zebrafish were detected by in situ antisense RNA hybridization and real-time PCR. RESULTS: 6-12 hpf, the early embryonic developmental stage, was a sensitive period that MTX affected cardiac formation of zebrafish. The retardant cardiac development and the evidently abnormal cardiac morphology was found in the MTX treatment group. The results of in situ antisense RNA hybridization showed that the expressions of BMP2b and HAS2 in the zebrafish heart were reduced in the MTX treatment group at 36 and 48 hpf. The real-time PCR results demonstrated that the BMP2b expression decreased at 12, 24, 36 and 48 hpf, and that the HAS2 expression decreased at 24, 36 and 48 hpf in the treatment group compared with the control group without MTX treatment. CONCLUSIONS: The inhibition of folic acid function may affect cardiac development of early embryos, resulting in a retardant development and a morphological abnormality of the heart in zebrafish, possibly by down-regulating the expressions of BMP2b and HAS2. ［Chin J Contemp Pediatr, 2007, 9 (2):159-163］