Article
Degeneration of cone photoreceptors in β2/β1 knock-in mice
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Authors
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S. J. Linke
- Klinik- und Poliklinik für Augenheilkunde / Kopf und Hautzentrum des Universitätsklinikum Eppendorf, Hamburg
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E. T. Matthiessen
- Klinik- und Poliklinik für Augenheilkunde / Kopf und Hautzentrum des Universitätsklinikum Eppendorf, Hamburg
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B. R. Zolmajd
- Klinik- und Poliklinik für Augenheilkunde / Kopf und Hautzentrum des Universitätsklinikum Eppendorf, Hamburg
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M. Schachner
- Zentrum für Molekulare Neurobiologie Hamburg (ZMNH)
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G. Richard
- Klinik- und Poliklinik für Augenheilkunde / Kopf und Hautzentrum des Universitätsklinikum Eppendorf, Hamburg
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K. Ruether
- Klinik für Augenheilkunde des Universitätsklinikums Charite, Berlin
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U. Bartsch
- Klinik- und Poliklinik für Augenheilkunde / Kopf und Hautzentrum des Universitätsklinikum Eppendorf, Hamburg
| Published: | September 22, 2004 |
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Outline
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Objective
We have previously characterized photoreceptor degeneration in β1/β1 knock-in mutants using morphological and electrophysiological techniques. The purpose of this study was to correlate the electrophysiological data with the kinetics of cone degeneration using peanut agglutinin labeling.
Methods
Electroretinograms (ERGs) were performed in ß2/ß1 knock-in mice (β2/β1-/-) and wild-type mice (β2/β1+/+) at 14, 30, 60, 90, 120, 150 and 270 days of age. Light- and dark-adapted ERGs were recorded using a Ganzfeld stimulus. C-waves were evoked by green light emitting diodes. Light and electron microscopy was performed on 17 days, 4 months and 9 months old mice of both genotypes. Retinal cones were analyzed in 14 days, 4 weeks and 8 weeks old β2/β1-/- and age-matched β2/β1+/+ mice using peanut agglutinin staining.
Results
Light microscopic analysis revealed a progressive degeneration of photoreceptor cells in β2/β1-/- mice. Degeneration of photoreceptor cells was almost complete in 270 days old mutants. We have shown previously that scotopic ERGs were significantly reduced at all developmental ages in β2/β1-/- mutants when compared to β2/β1+/+ mice. Moreover, ERG cone responses were not detectable in β2/β1 knock-in mice at any age analyzed (i.e. two weeks and older). Here, we demonstrate apparently similar numbers of cones with a similar morphology in 14 days old mutant and wild-type mice. In older mutants, however, we observed a pronounced degeneration of cones that was virtually complete in eight weeks old β2/β1 -/- mice.
Conclusions
The complete absence of a cone ERG in β2/β1 knock-in mice correlates with a progressive and rapid degeneration of cone photoreceptor cells. Degeneration of cones starts during the third postnatal week and is virtually complete in two months old β2/β1-/- mutant mice. The complete absence of a cone ERG in 14 days old mutants despite apparently normal numbers of cones might result from a functional deficit (i.e. insufficient Na+,K+-ATPase activity) of mutant cone photoreceptors.
Grant Identificaton: Supported by the Bundesministerium für Bildung und Forschung (01GN0126 an U.B.).
