Acute effects of dietary retinoic acid on ocular components in the growing chick
Acute effects of dietary retinoic acid on ocular components in the growing chick
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DOI：
10.1016/j.exer.2006.05.002
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发表时间：
2006-10-01
影响因子：
3.4
通讯作者：
Wallman, Josh
中科院分区：
文献类型：
--
作者：
McFadden, Sally A.;Howlett, Marc H. C.;Wallman, Josh
当小鸡的眼睛被诱导向近视或远视方向生长时，通过让它们佩戴眼镜片或扩散器，在视网膜和脉络膜中全反式视黄酸（RA）的合成和水平发生相反的变化。为了探索RA是否在眼睛生长的调节中起因果作用，我们每天两次或隔日或仅一次饲喂雏鸡RA（剂量为0.5至24 mg/kg）。用Hartinger验光仪测量屈光不正;用A型超声测量眼球长度、晶状体厚度和脉络膜厚度。使用HPLC测定眼组织中存在的RA的量。口服RA后8h内眼组织中RA含量明显增加。在以高于8 mg/kg的水平喂食RA后的第一天，眼球伸长的速率增加了两倍，脉络膜增厚和透镜增厚受到抑制。在一剂RA后的第二天，眼球伸长的速率被抑制，并且透镜比正常情况下增厚。尽管如此，重复给药的累积效应是眼睛变得比正常更长，透镜变得比正常更薄，屈光不正没有净变化。伸长的速率也增加喂养13-顺式RA，并减少柠檬醛，RA合成的抑制剂。令人惊讶的是，尽管眼睛伸长增加，但在黑暗中喂食RA的鸟类也具有正常的屈光不正，而佩戴+6 D或-6 D眼镜片的鸟类尽管RA导致眼睛伸长增加，但镜片补偿正常。这些结果表明，RA可能在协调的非视觉调节系统水平上发挥作用，该系统控制各种眼部成分的生长，并认为正视化并不完全取决于视力。皇冠版权所有（c）2006年出版的爱思唯尔有限公司保留所有权利。
When the eyes of chicks are induced to grow toward myopia or hyperopia by having them wear spectacle lenses or diffusers, opposite changes take place in the retina and choroid in the synthesis and levels of all-trans Retinoic Acid (RA). To explore whether RA plays a causal role in the regulation of eye growth, we fed young chicks RA (doses 0.5 to 24 mg/kg) either twice a day or on alternate days or only once. Refractive error was measured with a Hartinger refractometer; ocular length, lens-thickness and choroidal thickness were measured by A-scan ultrasound. The amount of RA present in ocular tissues was determined using HPLC. Oral delivery of RA effectively increased RA in ocular tissues within 8 h. During the first day after feeding RA at levels above 8 mg/kg, the rate of ocular elongation tripled, the choroid thickened and lens thickening was inhibited. The day following a dose of RA, the rate of ocular elongation was inhibited and the lens thickened more than normal. Nonetheless, the cumulative effect of repeated doses was that the eye became longer and the lens became thinner than normal, with no net change in refractive error. The rate of elongation was also increased by feeding 13-cis RA, and was reduced by citral, an inhibitor of RA synthesis. Surprisingly, birds fed RA while being kept in darkness also had normal refractive errors despite increased ocular elongation, and birds wearing either +6 D or -6 D spectacle lenses compensated normally for the lenses despite the enhanced ocular elongation caused by the RA. These results suggest that RA may act at the level of a coordinated non-visual regulatory system which controls the growth of the various ocular components, arguing that emmetropization does not depend entirely on vision. Crown Copyright (c) 2006 Published by Elsevier Ltd. All rights reserved.