The Role Of Retinoic Acid Signal Transduction Components In Guinea Pig Eyes With Lens Induced Myopia

ObjectiveTo observe the effort of retinoic acid(RA) signal transport system components on lens induced myopia in guinea pig, investigate the level of RA and the expression of retinoic acid receptor-β(RAR-β) and the interphotoreceptor retinoid-binding protein(IRBP) in retina, choroid and sclera of guinea pigs in order to better understand the mechanism by which RA regulates myopia.MethodsSixty-five guinea pigs were randomized into the normal controls(26 eyes, n=26), defocusⅠgroup(n=26) and defocusⅡg roup(n=26). Guinea pigs in the defocus groups wore -10.00D lenses on the right eyes: defocusⅠgroup, wore lens 14d, and defocusⅡ, treated eyes 28d. The left eyes were not worn lenses as self-control. The refraction and axial length were measured before and after wearing lenses respectively. Light microscope was used to observe the changes of the retina. The protein expression of IRBP and RAR-βwas detected by immunohistochemisty and western blot. RT-PCR was used to observe the level of IRBP and RAR-βmRNA. The level of RA in retina, choroid and sclera was detected by high performance liquid chromatography (HPLC).ResultsComparing with the control eyes, the lens-worn eyes of defocusⅠandⅡg roups became myopic and elongated(P<0.05, respectively) and the degree of defocusⅡg roup outweigh that of defocusⅠgroup. The thickness of retina in defocus eyes decreased and the number of retina cells reduced(P<0.05). The level of RA in retina, choroid and sclera was significantly set-up(P<0.05) ,and the two defocus groups have no statistic defferences(P>0.05). The protein expression and the mRNA level of IRBP and was significantly lower(P<0.05) in the treated eyes relative to control eyes, especially in defocusⅡgroup. The protein expression and the mRNA level of RAR-βin retina of the defocus groups increased significantly (P<0.05), while decreased significantly in choroid and sclera(P<0.05).Conclusion1.-10D lens wearing can induce guinea pigs to form myopia, and self-made lens with kt board frame for myopia can be used as an effective defocus method.2.Retinoic acid(RA) were expressed in retina, choroid and sclera of guinea pig, of which the choroid content highest. RA expression significant increased when the visual environment changed by lens defocus, suggesting that RA may take part in the formation of Lens Induced Myopia.3. The expression of retinoic acid receptor (RAR-β) increased in retina, while decreased in choroid and sclera of guinea pig with Lens Induced Myopia. The direction of RAR-βchanges consistent with the development of myopia, suggesting that RAR-βmay be involved in the formation and development of Lens Induced Myopia. The mechanism of RAR-βin Lens Induced Myopia may be related to optic centre.4.The expression of the interphotoreceptor retinoid-binding protein(IRBP) in retina in defocus eyes decreased, indicating that IRBP may be take a part in the formation and development of Lens Induced Myopia and IRBP may participate by means of visual centre.