Purchase this article with an account.
Lena Fuchs, Marita P Feldkaemper, Sally A McFadden; Bidirectional Changes in Type IV Collagen mRNA Expression in the Retina after Lens-Induced Myopia and Recovery in the Guinea Pig. Invest. Ophthalmol. Vis. Sci. 2017;58(8):1113.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Collagen is the main structural protein in the ECM and the development of high myopia is associated with reduced scleral collagen accumulation. However collagen also occurs throughout other ocular structures including Bruch’s and basement membranes and vessel walls in the retina (Marshall GE, Konstas AGP, Lee WR, 1993). Various collagens also contribute to vitreoretinal adhesion. We studied the expression of several of the collagens in the retina of myopic guinea pigs which is largely avascular, and report here the changes observed in Type IV Collagen (COL4A4).
Myopia was induced in one eye in 21 guinea pigs wearing a -5D spectacle lens from 4 days of age for 11 days. Whole retinas were extracted from both eyes at 15 days of age: after 11 days of lens-wear (myopia group, N=8); or after 11 days of lens-wear followed by 48 or 96 hrs of recovery (N=7 and N=6 respectively). Fellow eyes served as matched controls and were compared to an age-matched untreated group (N=6). Refractive error was measured in cyclopleged eyes on day 14 to confirm the degree of induced myopia. Semi-quantitative real-time PCR was used to quantify mRNA levels of Col4A4 in whole retina, using Beta-Actin as a reference gene.
Results: The mean difference in refractive error between the lens-treated and untreated eyes in the 21 animals was -6.2D (p<0.001). There was no difference in mean normalised expression (MNE) of mRNA for COL4A4 between eyes that recovered 96 hr from myopia and their fellow eyes (0.072 Vs. 0.062 respectively, p=0.67); or between fellow eyes and eyes from untreated animals. However, the MNE of COL4A4 was lower after 11 days of myopia (myopic: 0.067, fellow: 0.083, p<0.003) and tended to be higher after 2 days of recovery compared to fellow eyes (0.083 Vs. 0.074 respectively, p<0.08).
Conclusion: Collagen changes are not confined to the sclera in myopia, as we found down regulation of Type IV collagen in myopic guinea pig retina. This is consistent with the observed association of the gene for the laminin α2 subunit with human myopia (Verhoeven VJ, et al., 2013), since strong binding occurs between Type IV collagen and laminin. Collagen IV is associated with basement membranes, and its downregulation may be involved in the association between retinal detachment and myopia.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
This PDF is available to Subscribers Only