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K. Homma, M. Mandai, M. Takahashi; Evaluation of Visual Function in Retinal Degeneration Models by Multi-Electrode Array System. Invest. Ophthalmol. Vis. Sci. 2008;49(13):2214. doi: https://doi.org/.
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To test the neuronal function of the retina in the animal models of retinal degeneration, electroretinogram (ERG) is often performed. With mice, however, ERG system only enables us to investigate the retinal function as a whole and the positional information is not available. The aim of this study was to test if we could evaluate the neural function of the local areas of the retina by the application of micro-ERG technique using Multi-electrode array system.
The dark-adopted normal retinas of mice or rats were taken out from eye cups, and used for the ex-vivo study. Total of 8x8 electrodes in 1.2 mm square were positioned against each retina. Electrical recording was obtained with each probe after light stimulation. Pharmacological treatments were also performed to evaluate the nature of responses. Retinae from rd mice were also tested using this system.
After light stimulation, ERG-like a-waves and b-waves were detected with each electrode. The b-waves were inhibited by TTX, a sodium channel blocker, or tubocurarine, a nicotinic acetylcholine receptor antagonist, while the a-waves were not inhibited. These results indicate that the a-waves depend on the primary activation of rod photoreceptors and the b-waves represent the post-photoreceptor neural activities. The light-induced a-waves were observed in the retinas of P12 and older, with increase in amplitude until P15, by which time the response level was equivalent to that of adult retina to light stimulation. In P12-15 rd mice, only weak a-waves were detected and these waves decreased thereafter. In the N-methyl-N-nitrosourea (MNU)-treated rats, the retinal degeneration models, the a-waves were gradually decreased over the days after MNU injection.
These results suggest that micro-ERG technique is useful for investigations of local function of neuronal retinas.
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