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The frequency-response electroretinogram distinguishes cone and abnormal rod function in rd12 mice.

Dai X, Zhang H, He Y, Qi Y, Chang B, Pang JJ - PLoS ONE (2015)

Bottom Line: Unfortunately, the recorded ERG waveform was difficult to interpret because of a remarkably delayed peak-time, which resembles a rod response more than a cone response.Our results showed that normal rods respond to low frequency flicker (5 and 15 Hz) and that normal cones respond to both low and high frequency flicker (5-35 Hz).It is another simple and valid method for evaluating the respective contributions of retinal rods and cones.

View Article: PubMed Central - PubMed

Affiliation: Eye Hospital, School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China; Department of Ophthalmology, College of Medicine, University of Florida, Gainesville, Florida, United States of America.

ABSTRACT
Early studies on Rpe65 knockout mice reported that remaining visual function was attributable to cone function. However, this finding has been challenged more and more as time has passed. Electroretinograms (ERGs) showed that rd12 mice, a spontaneous animal model of RPE65 Leber's congenital amaurosis, had sizeable photopic responses. Unfortunately, the recorded ERG waveform was difficult to interpret because of a remarkably delayed peak-time, which resembles a rod response more than a cone response. Here, we compare flicker ERGs in animals with normal rod and cone function (C57BL/6J mice), pure rod function (cpfl5 mice), and pure cone function (Rho(-/-) mice) under different adaptation levels and stimulus intensities. These responses were then compared with those obtained from rd12 mice. Our results showed that normal rods respond to low frequency flicker (5 and 15 Hz) and that normal cones respond to both low and high frequency flicker (5-35 Hz). As was seen in cpfl5 mice, rd12 mice had recordable responses to low frequency flicker (5 and 15Hz), but not to high frequency flicker (25 and 35 Hz). We hypothesize that abnormal rods may be the source of residual vision in rd12 mice, which is proved correct here with double mutant rd12mice. In this study, we show, for the first time, that frequency-response ERGs can effectively distinguish cone- and rod-driven responses in the rd12 mouse. It is another simple and valid method for evaluating the respective contributions of retinal rods and cones.

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Amplitudes of frequency-response electroretinograms in 1 month old wild type, cpfl5, Rho−/−, and rd12 mice.Under dark-adaptation, stimulus intensity for dim and bright flicker were-1.85 log cd-s/m2 and 0 log cd-s/m2, respectively. Photopic responses were elicited with a +0.65 log cd-s/m2 stimulus. Flicker ERG amplitudes were evaluated. Columns and bars represent mean ± standard deviation (n = 5 mice). *indicates P < 0.001, NS = no statistical difference.
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pone.0117570.g003: Amplitudes of frequency-response electroretinograms in 1 month old wild type, cpfl5, Rho−/−, and rd12 mice.Under dark-adaptation, stimulus intensity for dim and bright flicker were-1.85 log cd-s/m2 and 0 log cd-s/m2, respectively. Photopic responses were elicited with a +0.65 log cd-s/m2 stimulus. Flicker ERG amplitudes were evaluated. Columns and bars represent mean ± standard deviation (n = 5 mice). *indicates P < 0.001, NS = no statistical difference.

Mentions: The C57BL/6J mice have normal rod and cone photoreceptor function. A dim scotopic stimulus (-1.85 log cd-s/m2) only activates rods and a bright stimulus (0 log cd-s/m2) activates both rods and cones. Dark-adapted flicker ERGs in C57BL/6J mice were detectable with dim light stimuli presented at a low frequency (5 and 15 Hz), but not with the same stimuli presented at a high frequency (25 and 35 Hz, Figs. 2A and 3). With bright stimuli, dark-adapted flicker ERGs were observed at all four frequencies examined (Figs 2A and 3). Cone-driven light-adapted flicker ERGs elicited by bright stimuli were confirmed with stimuli ranging between 5 and 35 Hz (Figs. 2A and 3).


The frequency-response electroretinogram distinguishes cone and abnormal rod function in rd12 mice.

Dai X, Zhang H, He Y, Qi Y, Chang B, Pang JJ - PLoS ONE (2015)

Amplitudes of frequency-response electroretinograms in 1 month old wild type, cpfl5, Rho−/−, and rd12 mice.Under dark-adaptation, stimulus intensity for dim and bright flicker were-1.85 log cd-s/m2 and 0 log cd-s/m2, respectively. Photopic responses were elicited with a +0.65 log cd-s/m2 stimulus. Flicker ERG amplitudes were evaluated. Columns and bars represent mean ± standard deviation (n = 5 mice). *indicates P < 0.001, NS = no statistical difference.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4338143&req=5

pone.0117570.g003: Amplitudes of frequency-response electroretinograms in 1 month old wild type, cpfl5, Rho−/−, and rd12 mice.Under dark-adaptation, stimulus intensity for dim and bright flicker were-1.85 log cd-s/m2 and 0 log cd-s/m2, respectively. Photopic responses were elicited with a +0.65 log cd-s/m2 stimulus. Flicker ERG amplitudes were evaluated. Columns and bars represent mean ± standard deviation (n = 5 mice). *indicates P < 0.001, NS = no statistical difference.
Mentions: The C57BL/6J mice have normal rod and cone photoreceptor function. A dim scotopic stimulus (-1.85 log cd-s/m2) only activates rods and a bright stimulus (0 log cd-s/m2) activates both rods and cones. Dark-adapted flicker ERGs in C57BL/6J mice were detectable with dim light stimuli presented at a low frequency (5 and 15 Hz), but not with the same stimuli presented at a high frequency (25 and 35 Hz, Figs. 2A and 3). With bright stimuli, dark-adapted flicker ERGs were observed at all four frequencies examined (Figs 2A and 3). Cone-driven light-adapted flicker ERGs elicited by bright stimuli were confirmed with stimuli ranging between 5 and 35 Hz (Figs. 2A and 3).

Bottom Line: Unfortunately, the recorded ERG waveform was difficult to interpret because of a remarkably delayed peak-time, which resembles a rod response more than a cone response.Our results showed that normal rods respond to low frequency flicker (5 and 15 Hz) and that normal cones respond to both low and high frequency flicker (5-35 Hz).It is another simple and valid method for evaluating the respective contributions of retinal rods and cones.

View Article: PubMed Central - PubMed

Affiliation: Eye Hospital, School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China; Department of Ophthalmology, College of Medicine, University of Florida, Gainesville, Florida, United States of America.

ABSTRACT
Early studies on Rpe65 knockout mice reported that remaining visual function was attributable to cone function. However, this finding has been challenged more and more as time has passed. Electroretinograms (ERGs) showed that rd12 mice, a spontaneous animal model of RPE65 Leber's congenital amaurosis, had sizeable photopic responses. Unfortunately, the recorded ERG waveform was difficult to interpret because of a remarkably delayed peak-time, which resembles a rod response more than a cone response. Here, we compare flicker ERGs in animals with normal rod and cone function (C57BL/6J mice), pure rod function (cpfl5 mice), and pure cone function (Rho(-/-) mice) under different adaptation levels and stimulus intensities. These responses were then compared with those obtained from rd12 mice. Our results showed that normal rods respond to low frequency flicker (5 and 15 Hz) and that normal cones respond to both low and high frequency flicker (5-35 Hz). As was seen in cpfl5 mice, rd12 mice had recordable responses to low frequency flicker (5 and 15Hz), but not to high frequency flicker (25 and 35 Hz). We hypothesize that abnormal rods may be the source of residual vision in rd12 mice, which is proved correct here with double mutant rd12mice. In this study, we show, for the first time, that frequency-response ERGs can effectively distinguish cone- and rod-driven responses in the rd12 mouse. It is another simple and valid method for evaluating the respective contributions of retinal rods and cones.

Show MeSH
Related in: MedlinePlus