In 2003, a study with Adult male rats test the hypothesis that glutamate causes apoptosis of retinal neurons

BACKGROUND:  via the excessive formation of peroxynitrite, and that the neuroprotective effect of the psychotropic Δ9-tetrahydroxycannabinol- (THC) or nonpsychotropic cannabidiol (CBD) is via the attenuation of this formation.

You can read the full article here => http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1892413/