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Jeannie Chen, Melvin I. Simon, Michael T. Matthes, Douglas Yasumura, Matthew M. LaVail; Increased Susceptibility to Light Damage in an Arrestin Knockout Mouse Model of Oguchi Disease (Stationary Night Blindness). Invest. Ophthalmol. Vis. Sci. 1999;40(12):2978-2982.
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purpose. To determine whether constitutive signal flow arising from defective
rhodopsin shut-off causes photoreceptor cell death in arrestin knockout
methods. The retinas of cyclic-light–reared, pigmented arrestin knockout mice
and wild-type littermate control mice were examined histologically for
photoreceptor cell loss from 100 days to 1 year of age. In separate
experiments, to determine whether constant light would accelerate the
degeneration in arrestin knockout mice, these animals and wild-type
control mice were exposed for 1, 2, or 3 weeks to fluorescent light at
an intensity of 115 to 150 fc. The degree of photoreceptor cell loss
was quantified histologically by obtaining a mean outer nuclear layer
thickness for each animal.
results. In arrestin knockout mice maintained in cyclic light, photoreceptor
loss was evident at 100 days of age, and it became progressively more
severe, with less than 50% of photoreceptors surviving at 1 year of
age. The photoreceptor degeneration appeared to be caused by light,
because when these mice were reared in the dark, the retinal structure
was indistinguishable from normal. When exposed to constant light, the
retinas of wild-type pigmented mice showed no light-induced damage,
regardless of exposure duration. By contrast, the retinas of arrestin
knockout mice showed rapid degeneration in constant light, with a loss
of 30% of photoreceptors after 1 week of exposure and greater than
60% after 3 weeks of exposure.
conclusions. The results indicate that constitutive signal flow due to arrestin
knockout leads to photoreceptor degeneration. Excessive light
accelerates the cell death process in pigmented arrestin knockout mice.
Human patients with naturally occurring mutations that lead to
nonfunctional arrestin and rhodopsin kinase have Oguchi disease, a form
of stationary night blindness. The present findings suggest that such
patients may be at greater risk of the damaging effects of light than
those with other forms of retinal degeneration, and they provide an
impetus to restrict excessive light exposure as a protective measure in
patients with constitutive signal flow in
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