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Wei-Hong Xiong, Merve Tekmen-Clark, Stephanie Lolich, Robert Duvoisin, Catherine Morgans; The Effect of PKCα on the Electroretinogram. Invest. Ophthalmol. Vis. Sci. 2013;54(15):6162.
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© ARVO (1962-2015); The Authors (2016-present)
Protein kinase C alpha (PKCα) is abundantly expressed in rod bipolar cells (RBCs), so much so that it is used as a cell marker to identify RBCs in retinal immunohistochemistry. Yet the physiological role of PKCα in RBCs is not well understood. In this study we aimed to determine the functional role of PKCα in vision by examining the effect of genetic deletion of PKCα on the electroretinogram (ERG).
Scotopic, photopic and flicker ERGs were recorded from PKCα knockout mice and their wild-type littermates. Genotyping was determined by PCR. Immunostaining and light microscopy were performed to examine the structure of the retina and the presence of RBC proteins, and to further confirm the knockout of PKCα.
No morphological changes were apparent in the PKCα knockout retina in mice from one month to one year of age. No differences in the a-wave of the scotopic ERG were observed between wildtype and PKCα knockout mice; the leading edge and amplitude were identical. The scotopic b-wave, however, was altered dramatically in the PKCα knockout mice, with a larger peak amplitude, longer implicit time and broader width of the b-wave peak. The oscillatory potentials of the scotopic ERG in the knockout mice were delayed, and the scotopic c-wave of the PKCα knockout mouse was also changed in that it disappeared in recordings to flashes of brief duration (less than 6 ms). In contrast, photopic ERGs of PKCα knockout mice were almost the same as that of their wild type littermates, consistent with the lack of detectable PKCα in cone bipolar cells. In response to flickering stimuli of differing frequencies (2 to 30 Hz), the amplitude of the ERG response was maximal at low temporal frequencies and gradually declined with increasing flash frequency. Compared with their wild type littermates, the amplitude of the flicker responses from PKCα knockout mice declined much faster with increasing stimulus frequency.
PKCα plays an important modulatory role in RBCs, regulating both the peak amplitude and temporal properties of the RBC light response in the rod visual pathway.
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