The Modulation Of The NMDAR₁ And Nitric Oxide-cyclic GMP Signaling Pathway In Form-deprivation Myopia Of Guinea Pig

Chapter one: The research of retinal morphology and uitrastructure in form deprivation myopia in guinea pigObjective: Form-deprivation myopia(FDM) was induced in guinea pig. The study of the changes in retinal morphology and ultrastructure in FDM of guinea pig.Methods: Sixty-six growing Guinea pigs were distribute to three groups: groupâ… was normal control without treatment; groupâ…¡underwent monocular form-deprivation by eyecover for 2 weeks; groupâ…¢deprived for 3 weeks. And the refraction and axial length of the eyes were measured after treatments.Then, histopathological changes in retina were observed by light microscope and electronic microscope, and the thickness of retina were measured.Result: In groupâ…¡, The deprived eyes were in mild myopia (-1.58D), the axial length in deprived eyes were elongated slightly than the control (7.957±0.118mm); In groupâ…¢, The deprived eyes were in medium myopia (-3.41D), the axial length in deprived eyes were extended dramatically than control eyes (8.122±0.086mm). The refraction and axial length of the deprived eyes increased significantly during the development of myopia(P＜0.05). The control eyes have the tendency to emmetropia; and the axial length were developed during the growth. The thickness of retina in deprived eyes became thinner compared with the deprived eyes; the numbers of cells in retina were reduced; the layer were disorderly in inner layer. The pathological changes just like apoptosis happened in electron microscope. The histopathological in entoretina changed obviously.Conclusion: Guinea pig could be used as an practical and economical mammalian model of Form-deprivation myopia by non-invasived unilatend deprived eyecover. With the development of myopia, The thickness of retina became thinner. Entoretina played important role in mechanism of myopia. Chapter two: The Expression of NMDAR and nitric oxide-cyclic Guanine Monophosphate signaling pathway in form-deprivation myopia of Guinea pig's retinaObjective: To characterize the changes of NMDAR and nitric oxide-cyclic guanine monophosphate (NO-cGMP) signaling pathway in form-deprivation myopia of Guinea pig's retina. To explore the possible retina signaling pathway for regulation of eye growth.Methods: To every group of guinea pigs, the protein level of NMDAR1 was measured by immunohistochemistry and Western Blot; the NMDAR1 mRNA was measured by RT-PCR; ncNOS was detected by hybridization in situ; cyclic GMP was detected by radioimmunochemistry. Bivariate correlations analyze the relationship between ncNOS and cyclic GMP expression in retina.Results: In groupâ… untreated for normal control, the positive expression of NMDAR1, ncNOS and c-GMP could be seen in guinea pig's retina. The expression of NMDAR1 and ncNOS majory located in entoretina. The expressions of them in both eyes had no significance difference(P＞0.05). In groupsâ…¡andâ…¢, the expression of NMDAR₁, ncNOS and c-GMP were up-regulated in the deprived followed with the covering time consuming. All of them had significance difference compared with contral eyes (P＜0.05). The expression of ncNOS was significantly correlative with the that of c-GMP in retina (correlation coefficient 0.805).Conclusions: Significantly up-regulation can be seen in both the expression of NMDAR1 in protein level and mRNA, ncNOS and c-GMP in retina of the FDM. Abnormal visual signal should control myopia by the NMDAR and NO-cGMP signaling pathway in retina.Chapter three: The NMDAR1 inhibitor MK801 control the form-deprivation myopia of guinea pigObjective: With the NMDAR₁ inhibitor MK801 intravitreous injected, we identified the mechanism of myopia by the changes of the expression in NMDAR₁ and nitric oxide-cyclic GMP signaling pathway.Methods: 72 Guinea pigs in three were divided into six groups, group A (control), group B (3 weeks form-deprivation in right eye), group C1 (3 weeks form-deprivation in right eye+saline), group C2 (3 weeks form-deprivation in right eye +MK801 lng), group C3 (3 weeks form-deprivation in right eye + MK801 10ng), group C4 (3 weeks form-deprivation in right eye + MK801 100ng). After MK801 or saline had been injected into vitreous of form-deprivated eyes, the refraction and axial length of the eyes were measured, the expression of NMDAR₁ and ncNOS in retina were detected.Results: The refraction and axial length of all right eyes in group B, C1, C2, C3, C4 remarkly increased in comparison with group A. The refraction,axial length and the expression of ncNOS and NMDAR₁ in two groups of B and C had no significance difference(P＞0.05). Compared C2, C3, C4 to group C1, The refraction,axial length and the expression of NMDAR₁ and ncNOS reduced (P＜0.05). They had very good correlation with the density of MK801.Conclusions: Different concentration MK801 injected in vitreous can restrain myopia by down-regulated the expression of NMDAR₁ and nitric oxide-cyclic GMP signaling pathway. It worked as concentration dependent.