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L. Ma, C. Hou, R.A. Adelman, J. Zhang, Y. Liu, M.X. Zhang, M. Yan; Effects of Monocular Visual Deprivation on Pattern VEP and Binding Parameters of GluRs In Developing Kittens’ Visual Cortex . Invest. Ophthalmol. Vis. Sci. 2005;46(13):5682.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To explore the cortical mechanism of amplyopia and provide the studying evidence of possible medicine therapy for amplyopia on molecular level. Methods: Lid suture to produce monocular visual deprivation was performed on 5 kittens at 3 weeks of age; 6 kittens were used for controls. Three months later, pattern visual evoked potential (PVEP) was recorded and characteristics of [3,4–3H]L–glutamate binding to the kittens’ visual cortical membrane preparation were studied by a radiolabelled ligand receptor binding assay on the 11 kittens. Results: 1. The PVEP evoked through the eyes in normal kittens consisted mainly of one negative (N1) and one positive (P) component. The latent time of N1 and P component was 16.02ms and 45.87ms respectively. The difference of latent time and amplitude between the right eye and left eye was not significant (P>0.05). 2. The PVEP evoked through the operated eyes manifested two forms: 1) the wave of PVEP extinguished; 2) the latent time of P component delayed and its amplitude decreased. Either compared to contralateral eyes or to control eyes, the difference was significant. 3. Using different spatial frequency reversing pattern as stimuli, the results showed: 1) in control group, the latent time of P component delayed along with the increasing of spatial frequency. Its amplitude increased when spatial frequency was less than 0.1c/d; after that, along with the increasing of spatial frequency, the amplitude reduced significantly. 2) in treatment group, neither for latent time nor for amplitude, the spatial frequency tune was in existence. 4. After 3 months, the GluRs binding sites in the visual cortex of kittens with monocular deprivation decreased significantly, compared to control group (P<0.001); and the value of KD was greater than that of control group (P<0.001), suggested the affinity of GluRs decreased, as compared with that of normal kittens. 5. Either in the control group or treatment group, the Hill coefficient was all close to 1, indicated: 1) [3,4–3H]L–glutamate binded to single–site receptor, obeyed to mass action law; 2) even if there were multi binding sites in GluRs, the affinity of these sites to [3,4–3H]L–glutamate was almost identical. Neither positive nor negative cooperation effect existed. Conclusions: Monocular deprivation does affect the characteristics of PVEP and the binding parameters (KD and Bmax) of GluRs, suggests that the occurrence of amblyopia does have molecular foundation.
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