[A study on the expression of opsins in form-deprived myopia retina of guinea pig].

Objective: To investigate the expression of cone opsins in form-deprived myopia (FDM) of guinea pig.

Methods: Twenty-eight pigmented guinea pigs aged one-week were randomly divided into two groups: FDM group (n = 14) and control group (n = 14). White translucent vinyl diffuse attached to one randomly selected eye was used to deprive eyes of form-vision in FDM group. RT-PCR and immunohistochemistry were performed to compare the opsin mRNA expression and spatial density of photoreceptor opsin in the ventral, central and dorsal retinal areas of two groups using antibody against short and medium-wave-length-sensitive cone opsin. Slides were viewed using Leica confocal microscope and Leica light microscope.

Results: The distribution of opsin across the guinea pig retinae as determined by antibody labeling of cone opsin was asymmetric, with the dorsal retina dominated by M-opsin, and the ventral retinae by S-opsin. But the ventral area also showed positive staining for the M-opsin. Opsin spatial density decreased with increasing retinal eccentricity for both M and S opsins. The spatial density of S-opsin decreased most steeply for eccentricity up to one-third distance from optic disc to retinal edge. The spatial density of M-opsin gradually decreased with eccentricity. The expression of spatial density of M-opsin was higher than that of S-opsin in all three regions. The expression of density of S-opsin in normal control eye is as follow: (805.0 +/- 203.3) mm(-2) (ventral); (100.0 +/- 57.7) mm(-2) (dorsal); (1637.2 +/- 314.1) mm(-2) (Central). FDM eye: (640.9 +/- 196.8) mm(-2) (ventral); (1016.7 +/- 144.6) mm(-2) (central); (70.9 +/- 30.8) mm(-2); where The expression of spatial density of M-opsin in normal control eye are: (946.2 +/- 388.5) mm(-2) (dorsal); (1666.7 +/- 137.8) mm(-2) (central); (175.0 +/- 100.9) mm(-2) (ventral). FDM eye: (1436.7 +/- 366.0) mm(-2) (dorsal); (2780.0 +/- 180.5) mm(-2) (central); (318.2 +/- 172.7) mm(-2) (ventral). The results of RT-PCR examination showed that the relative optical density (OD) value of M-opsin and S-opsin are: 1.06 +/- 0.07 (FDM eye), 0.51 +/- 0.10 (control eye), and 0.70 +/- 0.07 (FDM eye), 1.25 +/- 0.06 (control eye) respectively. The expression of both opsins in FDM eyes was significant differences compared with control (P < 0.05).

Conclusion: FDM can increase the expression of M-opsin and decrease the S-opsin expression in guinea pig. cone opsins may play a role in the development of myopia.