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Nicole Kueng-Hitz, Christian Grimm, Nicola Lansel, Farhad Hafezi, Lihua He, Donald A. Fox, Charlotte E. Remé, Günter Niemeyer, Andreas Wenzel; The Retina of c-fos−/− Mice: Electrophysiologic, Morphologic and Biochemical Aspects. Invest. Ophthalmol. Vis. Sci. 2000;41(3):909-916.
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purpose. Mice without a functional c-Fos protein
(c-fos −/− mice) do not exhibit light-induced
apoptotic cell death of rods in contrast to their wild-type littermates
(c-fos +/+ mice). To analyze the consequences
of the absence of c-fos in the retina, we investigated
whether the retinas of c-fos −/− mice have
a reduced capacity to absorb and transduce light compared with c-fos +/+ mice.
methods. Retinal function was evaluated in dark-adapted mice by full-field
electroretinograms (ERGs) over more than 6 log units of intensity.
Retinal morphology was studied by light- and electron microscopy.
Arrestin and the heat shock protein 70 (Hsp70) were detected by Western
blot analysis. The rhodopsin content and the kinetics of rhodopsin
regeneration were determined in retinal extracts.
results. Although the configuration of the ERGs was comparable in both groups of
mice, c-fos −/− mice showed a marked
variability in all quantitative ERG-measures with lower mean
amplitudes, longer latencies, and a 0.9-log-unit lower b-wave
sensitivity on average. Morphometry showed that c-fos −/− mice have 23% fewer rods on
average, whereas the number of cones was comparable among c-fos +/+ and c-fos −/− mice. Arrestin levels appeared
slightly reduced in c-fos −/− mice when
compared with c-fos +/+ mice, whereas Hsp70
levels were comparable in both genotypes. The kinetics of rhodopsin
regeneration were similar, but c-fos −/− mice had a 25% lower rhodopsin content on average.
conclusions. Compared with c-fos +/+ mice, retinal
function in c-fos −/− mice is attenuated to
a variable but marked degree, which may be, at least in part, related
to the reduced number of rods and the reduced rhodopsin content.
However, c-fos does not appear to be essential for the
ability to absorb photons, nor for phototransduction or the function of
second-order neurons. The resistance to light-induced apoptosis of
photoreceptor cells in c-fos −/− mice may
result from the acute deficit of c-fos in the apoptotic
cascade rather than from developmental deficits affecting rod
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