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E.-J. Lee, M. Padilla, D. Merwine, N. Grzywacz; Visaul Experience Regulates the Integrity of Horizontal Cells in the Mouse Retina. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5684.
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© ARVO (1962-2015); The Authors (2016-present)
Dark rearing during development alters normal refinement of connections, neurotransmitter expression, and physiological function in the retina. Do other forms of visual rearing also affect retinal development? We investigated the effects of rearing in visual environments with light but abnormal spatial contrasts on the anatomy of retinal neurons in the mouse. These abnormal environments included those with contrast-rich images (checkerboards) or with no contrasts (spatially homogeneous gray images).
Sixteen litters of C57BL/6J black mice (The Jackson Laboratory Bar Harbor, Maine) were used for control (four litters), dark-rearing (four litters), contrast-rearing (four litters), and non-contrast-rearing (four litters) studies. Mice were sacrificed at postnatal (P) days 12, P21, P30, and P60. Control animals were maintained on a daily 12 h light/dark cycle. In turn, dark-reared animals were raised under completely dark conditions from P0. Checkerboard and non-contrast animals were raised in contrast and non-contrast environments, respectively for 6 h per day from P10. They were otherwise in total darkness. We studied the anatomy of retinal neurons in the mouse by immunocytochemistry.
In postnatal-day 30 (P30) control, P30-dark-reared, and P30-checkerboard-reared retinas, horizontal cell processes ramified normally in the outer-plexiform-layer (OPL). However, in P30-gray-image-reared retinas, horizontal cell processes emerged from the OPL and ramified in the inner-nuclear-layer (INL). Thus, exposure to light without spatial structure is insufficient for normal development of the horizontal-cell network and may result in abnormal visual processing. In contrast, there were no morphological changes in amacrine cells, rod bipolar cells, cone bipolar cells or photoreceptors after rearing in the non-contrast environment.
Our data demonstrate that light without spatial contrast (e.g, with spatially homogeneous gray images) alters the integrity of horizontal cells, and may thus affect normal visual processing. Similar horizontal-cell changes were found in a mouse model of retinitis pigmentosa. We thus propose that retinitis pigmentosa and non-contrast development may share some mechanisms. Furthermore, our findings with non-contrast development may be relevant for young patients with cloudy vision (e.g. cataract).
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