BACKGROUND Various intestinal morphological alterations have been reported in cultured fish fed diets with high contents of plant ingredients. Since 2000, salmon farmers have reported symptoms indicating an intestinal problem, which we suggest calling lipid malabsorption syndrome (LMS), characterized by pale and foamy appearance of the enterocytes of the pyloric caeca, the result of lipid accumulation. The objective of the present study was to investigate if insufficient dietary choline may be a key component in development of the LMS. RESULTS The results showed that Atlantic salmon (Salmo salar), average weight 362 g, fed a plant based diet for 79 days developed signs of LMS. In fish fed a similar diet supplemented with 0.4% choline chloride no signs of LMS were seen. The relative weight of the pyloric caeca was 40% lower, reflecting 65% less triacylglycerol content and histologically normal gut mucosa. Choline supplementation further increased specific fish growth by 18%. The concomitant alterations in intestinal gene expression related to phosphatidylcholine synthesis (chk and pcyt1a), cholesterol transport (abcg5 and npc1l1), lipid metabolism and transport (mgat2a and fabp2) and lipoprotein formation (apoA1 and apoAIV) confirmed the importance of choline in lipid turnover in the intestine and its ability to prevent LMS. Another important observation was the apparent correlation between plin2 expression and degree of enterocyte hyper-vacuolation observed in the current study, which suggests that plin2 may serve as a marker for intestinal lipid accumulation and steatosis in fish. Future research should be conducted to strengthen the knowledge of choline's critical role in lipid transport, phospholipid synthesis and lipoprotein secretion to improve formulations of plant based diets for larger fish and to prevent LMS. CONCLUSIONS Choline prevents excessive lipid accumulation in the proximal intestine and is essential for Atlantic salmon in seawater.

中文翻译：

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补充胆碱可防止饮食引起的肠道粘膜脂质积聚在熏鲑大西洋鲑（Salmo salar L.）中。

背景技术已经报道了在饲喂高含量植物成分的养鱼饲料中各种肠道形态学变化。自2000年以来，鲑鱼养殖者报告了表明存在肠道问题的症状，我们建议将其称为脂质吸收不良综合征（LMS），其特征是幽门盲肠肠上皮细胞呈淡淡泡沫状，这是脂质积累的结果。本研究的目的是调查饮食中胆碱是否不足可能是LMS发展的关键因素。结果结果表明，平均重量为362 g的大西洋鲑（Salmo salar），以植物性饮食喂养了79天，出现了LMS症状。在饲喂类似饮食并添加0.4％氯化胆碱的鱼中，没有发现LMS的迹象。幽门盲肠的相对重量降低了40％，反映出三酰甘油含量和组织学正常的肠粘膜减少了65％。补充胆碱进一步提高了鱼类的特定生长18％。与磷脂酰胆碱合成（chk和pcyt1a），胆固醇转运（abcg5和npc1l1），脂质代谢和转运（mgat2a和fabp2）以及脂蛋白形成（apoA1和apoAIV）有关的肠道基因表达的伴随变化证实了胆碱对脂质转换的重要性在肠道中及其预防LMS的能力。另一个重要观察结果是当前研究中观察到的plin2表达与肠上皮细胞过度疏松程度之间存在明显的相关性，这表明plin2可能是鱼类肠道脂质蓄积和脂肪变性的标志。应该进行进一步的研究以增强胆碱的知识。在脂质运输，磷脂合成和脂蛋白分泌中的重要作用，以改善大型鱼类的植物性饲料配方并防止LMS。结论胆碱可防止脂质在近端肠内过度积聚，对于海水中的大西洋鲑鱼至关重要。