Correlational Research On The Changes Of RGS2and Collagen In Guinea Pig Sclera Of Form Deprivation Myopia

Myopia is the most common visual disorder which affects approximately half of the world’s young adult population. High myopia is associated with an increased risk of pathological ocular complications and may lead to blinding disorders such as premature cataracts, glaucoma, retinal detachment, and macular degeneration. Postnatal scleral growth is under the control of retina-choroid-sclera signal pathway or its downstream effectors. Sclera remodeling occurs during axial elongation in myopia and scleral fibroblasts are the key cells in this process. Atropine, a nonselective muscarinic antagonist, is proved to be useful in stopping progress of myopia. But the mechanism by which atropine produces its action is still unclear. Atropine is a pan-muscarinic antagonist. Muscarinic receptor (mAChR) is GPCR (G protein-coupled receptor) which plays important roles in the "stop" signal of myopic progression. RGS2is one of the most important RGS subtypes which inhibit mACh-mediated pathways. Since RGS2can modulate the synthesis of collagen in cardiac fibroblasts, we are interested in the question that whether it may also function on scleral fibroblasts. This study was designed to discuss the relationship between RGS2and collagen in myopic sclera of guinea pig and determine whether the express of RGS2in sclera changes when form deprivation myopia model is intervened by atropine.PURPOSE To investigate changes in the expression of regulator of G-protein signaling2(RGS2) and type I collagen in sclera of guinea pig eyes with form deprivation myopia.METHODS A hundred and twenty2-week-old guinea pigs were divided randomly and equivalently into four groups with30in each group. The form-deprived group was made monocular form-deprived with translucent goggles in the right eyes. In the atropine group, the guinea pigs were raised with a diffuser placed over the right eye and an intravitreal injection of atropine solution was administered. In the saline group, the guinea pigs were raised with a diffuser placed over the right eye and an intravitreal injection of saline was administered. The control group served without any treatment. The left eyes remained untouched as a self control. Four weeks later, measure the refraction, anterior segment depth, lens thickness and axial length (AXL) of each guinea pig. Hematoxylin-eosin was used to observe the changes of posterior sclera. The expression of RGS2and type I collagen in sclera were measured by real-time PCR and western blot.RESULTS The relative refraction in diopter of the control group is (-4.38±0.23) D; the relative vitreous chamber depth is (0.15±0.04)mm; the relative AXL is (0.18±0.02)mm, all of which were higher and showed a significant difference from that of the control group (P<0.05). The relative refraction in diopter of the atropine group is (-3.24±0.27) D; the relative vitreous chamber depth is (0.13±0.03)mm; the relative AXL is (0.13±0.03)mm, all of which were higher and showed a significant difference from that of the saline group (P<0.05). Hematoxylin-eosin also showed that the posterior sclera in FDM group was thinner than control group(P<0.05); the posterior sclera in saline group was thinner than atropine group(P<0.05). Real-time PCR and Western blot showed that the expression of RGS2in FDM group was higher compared with control group (P<0.05); the expression of RGS2in saline group was higher compared with atropine group (P<0.05). Real-time PCR and Western blot showed that the expression of type I collagen in FDM group was lower compared with control group(P<0.05); the expression of type I collagen in saline group were lower compared with atropine group(P<0.05).CONCLUSIONS The expression of RGS2bin FDM guinea pigs was higher than that in the control ones; the expression of type I collagen in FDM guinea pigs was lower than that in the control ones. The development of myopia in guinea pig was inhibited by atropine. The expression of RGS2in saline guinea pigs was higher than that in the atropine ones; the expression of type I collagen in saline guinea pigs was lower than that in the atropine ones. RGS2may play a role in the scleral fibroblast and control the expression of collagen in the development of myopia treated with atropine in guinea pigs.