摘要或動機

長期以來，臨床研究發現會影響人類胚胎的正常發育，造成胚胎畸形、成長遲緩等現象，稱為胎兒酒精症候群（fetal　alcohol　syndrome），但是其病理機制仍不清楚。最近的研究發現斑馬魚胚胎對於酒精有非常靈敏的反應，出現明顯的發育異常現象，例如心臟膨大、眼睛縮小、骨頭變形等現象，與人類胎兒酒精症候群相似，顯示斑馬魚非常適合作為研究胎兒酒精症候群的模式動物。在本實驗中，我們針對酒精影響視網膜神經發育的現象進行探討，並且也利用基因晶片篩選出胚胎發育時期受酒精影的的基因轉錄子，藉以了解酒雞造成胚胎畸形發育的機制。實驗結果顯示在眼睛發育過程中，1.5% 酒精浸泡會抑制視網膜神經細胞的分層（Lamination），而進一步利用RNA定位雜交的方式以眼睛的標示基因rx1、pax6b、six3b、alpha-crystallin、rho、neuroＤ、huC觀察他們的表現，發現酒精會減少視網膜神經細胞的分化，造成眼睛發育的缺陷。在基因晶片的分析中，我們發現酒精處理會抑制許多控制眼睛發育的基因調控子的表現，包括了crx、rybp、irx4a、optx2、rx1、brn3b1 與 vsx1等，此外約有16%的眼睛相關基因液受到酒精的抑制，遠高於其他基因受抑制的比例，顯示眼睛是酒精傷害最嚴重的區域之一。我們從實驗結果得知酒精並未對胚胎發育初期眼睛的發育造成明顯的影響，但是隨後由於控制細胞分化的幾個重要基因受到酒精抑制作用，造成視網膜神經細胞的分化停止，引起眼睛的異常發育的情況。It was known that prenatal alcohol exposure may cause serious birth　defects and developmental disabilities. The molecular mechanism of this　fetal alcohol syndrome still remains unclear. Here we used zebrafish embryo　as a model to investigate the toxic effect of alcohol in retinal development.　The histochemical analysis revealed that the cell lamination was prohibited　by alcohol incubation. It appears that the retinal cell differentiation was　inhibited. As revealed by whole mount RNA in situ hybridization, it appears　that the transcription of a number of retinal-related regulatory genes,　including rx1, pax6b, six3b, alpha-crystallin, rho, neuroD and huC, were all　inhibited in zebrafish embryo by alcohol exposure. The transcriptional　profile of alcohol-exposed embryos was also compared with normal　embryos by microarray analysis at different stages. It appears that 16% of　retinal-related genes were all repressed by 1.5% alcohol incubation,　including several retina-related transcriptional factors, including crx, rybp,　irx4a, optx2, rx1, brn3b1and vsx1. Our results suggest that alcohol did not　interfere the early development of the eye, but has inhibited the final cell　differentiation of retina cells. This study helps us understand the molecular　mechanism of alcohol-mediated retinal malformation.