Effect of green flickering light on myopia development and expression of M1 muscarinic acetylcholine receptor in guinea pigs.

Abstract

To investigate the effects of green flickering light on refractive development and expression of muscarinic acetylcholine receptor (mAChR) M1 in the eyes of guinea pigs. Thirty guinea pigs (15-20 days old) were randomly divided into three groups (n=10/group). Animals in group I were raised in a completely closed carton with green flickering light illumination. Those in group II were kept in the open top closed carton under normal natural light. Guinea pigs were raised in a sight-widen cage under normal natural light in group III. The refractive status and axial length were measured before and after 8 weeks' illumination. Moreover, total RNA extracted from retinal, choroidal, and scleral tissues were determined by real-time reverse transcription polymerase chain reaction (RT-PCR). The expressions of the receptor M1 were also explored in the retina, choroid, and sclera using immunohistochemistry. There was a remarkable reduction in refractive error and increase in axial length after 8-weeks' green flickering light stimulation (P<0.001). The expression of M1 receptor mRNA in sclera and retina in myopia group were remarkably lower than that in group II and III (P<0.01). Significant reduced expression of M1 receptor stimulated by green flickering light in retina and sclera tissues were also observed (P<0.05). However, there was no M1 receptor expression in choroid in 3 groups. Myopia can be induced by 8 weeks' green flickering light exposure in the animal model. M1 receptor may be involved causally or protectively in myopia development.