To further our ability to rationally develop therapies for photoreceptor cell death, we sought to investigate the cell signaling associated with sarpogrelate-mediated neuroprotection. Sarpogrelate-mediated retinal protection involves a transient activation of the MAPK/ERK pathway, although this pathway alone does not account for the full effect of neuroprotection. These changes were prevented by sarpogrelate treatment. LE caused significant changes in the expression of genes involved in iron metabolism, oxidative stress, and apoptosis. Inhibition of ERK1/2 with MEKi pretreatment led to attenuation of sarpogrelate-mediated neuroprotection. Temporal analysis further demonstrated a transient activation of ERK1/2, starting with an early inhibition 20 minutes into LE, a maximum activation at 3 hours post LE, and a return to baseline at 7 hours post LE. Sarpogrelate led to an activation of the MAPK/ERK pathway.
To determine the effects of sarpogrelate on gene expression, a qPCR array measuring the expression of 84 genes involved in oxidative stress and cell death was performed 48 hours post LE. The degree of neuroprotection was evaluated with spectral-domain optical coherence tomography (SD-OCT) and electroretinography (ERG). Since both methodologies implicated MAPK/ERK activation, the functional significance of sarpogrelate-mediated ERK1/2 activation was examined by inhibition of ERK1/2 phosphorylation via pretreatment with the MEK inhibitor (MEKi) PD0325901. To confirm microarray results and define temporal changes, Western blots of select GPCR signaling proteins were performed. Following LE, retinas were harvested for a high-throughput phosphorylation microarray to quantify activated phosphorylated proteins in G protein–coupled receptor (GPCR) signaling. To characterize the mediators of 5-HT 2A serotonin receptor–driven retinal neuroprotection.Īlbino mice were treated intraperitoneally with saline or sarpogrelate, a 5-HT 2A antagonist, immediately before light exposure (LE).
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