Changes in retinal and choroidal gene expression during development of refractive errors in chicks

Abstract

Purpose: During growth, the retina analyzes the projected image to achieve a close match between eye length and focal length. Because the messengers released by retina and choroid are largely unknown, genes that are differently expressed in response to changes in the retinal image were identified. In addition, because glucagon may be important in the visual control of eye growth, the transcript levels of proglucagon were studied.

Methods: Reverse transcription-polymerase chain reaction differential display was used to identify genes that were differentially expressed in chick eyes that were deprived of sharp vision or treated with positive or negative lenses. Differences were analyzed through sequencing and database searches and confirmed by Northern blot analyses.

Results: Combining 40 and 33 arbitrary primers with 3 oligo-dT-primers, approximately 48% and 40% of the retinal and choroidal mRNAs were screened, respectively. Twelve differences were detected in retinal tissue and five in choroidal tissue after 6 to 24 hours of exposure to defocus. Only one of 10 sequenced products could be identified as cytochrome-c oxidase, subunit I. Northern blot analysis confirmed its twofold upregulation after positive lens wear and also changes in four other unknown genes. Finally, it was shown that retinal glucagon mRNA content increased after treatment with positive lenses.

Conclusions: Visual conditions that induce refractive errors produce changes in gene expression in retina and choroid within 1 day. In line with previous immunohistochemical data, it was found that the amount of glucagon mRNA was upregulated during wearing of positive lenses.