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S. L. Ball, B. Hanzlicek, S. Mohr; Recovery Pattern of Rod and Cone Mediated Postreceptoral Electroretinogram Responses Following Unilateral Optic Nerve Crush. Invest. Ophthalmol. Vis. Sci. 2010;51(13):2484.
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© ARVO (1962-2015); The Authors (2016-present)
Injury to the optic nerve (ON) causes loss of ganglion cells and activation of Müller cells. While studies of retinal function following ON crush have typically focused on ganglion cell function, secondary injury responses mediated via activated Müller cells likely contribute significantly to functional losses. Bipolar cell contributions are dominant in the electroretinogram (ERG) and thus mask postreceptoral contributions from retinal cells, such as Müller cells. This impediment is abrogated by the absence of a b-wave in the dark adapted ERG of the Nyxnob1 mouse. ERGs recorded under dark adapted conditions in the Nyxnob1 mouse reveal activity generated by Müller cell Kir4.1 currents or slow PIII. Here we use the ERG to investigate the effects of unilateral ON crush on Müller and postreceptoral cell function in Nyxnob1 mice.
A mild unilateral ON crush was induced in Nyxnob1 mice at 8-12 weeks of age. ERG analysis was performed at 3, 7, or 14 days post ON crush. Dark and light adapted responses were recorded to a series of light intensities from both eyes (crushed and uncrushed) simultaneously.
Dark adapted ERG a-wave and slow PIII response amplitudes to high light intensity stimuli were decreased in the crushed eye as compared to the uncrushed eye on postoperative day 3 but all response amplitudes returned to normal by day 14 postoperative. Light adapted ERG a-wave responses to high light intensities were also decreased as compared to the uninjured eye at day 3 postoperative and also returned to normal by day 14 postoperative. However, the amplitude of ERG light adapted postreceptoral contributions presumablely including slow PIII currents generated by Müller cells remained decreased from day 3 -14 postoperative.
The results demonstrate that the rate of functional recovery following ON crush of cone mediated responses is slower than that of rod mediated postreceptoral responses. These results support the hypothesis that activated Müller cells may selectively impede recovery of cone mediated function following ON injury.
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