FIGURE 10.

The events that occur after clinical light exposure that cause photoreceptor degeneration in the T4R RHO mutant retina in the presence or absence of systemic DEX. In the untreated mutant retina, exposure to light resulted in phosphorylation of ERK1/2 and c-Fos and increased DNA binding by AP-1 (AP-1 activation). Our previous results suggest that AP-1 activation results in a cell survival response initiated in Müller cells.¹⁹ Treatment with systemic DEX inhibits phosphorylation of ERK1/2 and c-Fos, and AP-1 DNA binding activity is not increased. This may result in a decreased cell survival response mediated by Müller cells. However, regardless of systemic DEX treatment, clinical light exposure of the T4R RHO mutant retina leads to photoreceptor cell death.