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| Molecular basis of development of refractive errors in an animal model. |
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| 作者：Sheila G… 文章来源：School of psychological sciencesLa Trobe UniversityMelbourne 3086, Australia 点击数1285 更新时间：2005/7/5 14:29:00 文章录入：aya610 责任编辑：毛进 |
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| Purpose -Although clinical myopia (short sightedness) affects the health and quality of life of more than 50% of the world, its aetiology is unknown. However we have recently shown in the chick model that fluid movements between the retina and choroid across the Retinal Pigment Epithelium are temporally and morphologically related to the changes in ocular growth and refraction seen during recovery from form deprivation myopia. Such fluid movements would be expected to be associated with changes in relative ion concentration and expression of aquaporins the specialized water channels over time of recovery. Thus we investigated the temporal sequence of relative ionic abundances of potassium, sodium, chloride, phosphorus and sulphur at five levels cross the retina and choroid in the first 5 days post-occlusion.
Methods: Thirty hatchling chickens were monocularly occluded with translucent goggles from day 3 to 10 and then given T=0, 24, 48, 72, 96 and 120 hours of unrestricted visual experience, prior to retinoscopy and ultrasonography. Enucleated eyes were prepared for aquaporins (AQP4) immunohistochemistry or immediately fixed in liquid nitrogen slush and then freeze-dried for 12 hours or bulk frozen. Specimens were examined with a Cambridge S-360 SEM and Iridium X-ray analyzer.
Results: - Elemental microanalysis indicates that abundance of potassium, sodium and chloride ions are significantly raised in the area of the subretinal space and choroid at occluder removal but fall to below normal levels during refractive normalization (T= 24 -72hours) while immunohistochemical studies indicate that expression of the specialized water channels the AQP4 aquaporins also increase during form deprivation.
Conclusions: These results demonstrate that FD myopia is associated with increases in relative abundance of Na+ and Cl- in the extravascular choroid/outer retina and an increase in abundance of K+ in the RPE/outer retina and altered expression of AQP4 water channels near the vitreal surface. The abnormal ion abundances decrease with hours of normal visual experience and as emmetropization is achieved.
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