Our recent studies implicate the transient receptor potential vanilloid-1 (TRPV1) channel as a mediator of retinal ganglion cell (RGC) function and survival. With elevated pressure in the eye, TRPV1 increases in RGCs, supporting enhanced excitability, while Trpv1 -/- accelerates RGC degeneration in mice. Here we find TRPV1 localized in monkey and human RGCs, similar to rodents. Expression increases in RGCs exposed to acute changes in pressure. In retinal explants, contrary to our animal studies, both Trpv1 -/- and pharmacological antagonism of the channel prevented pressure-induced RGC apoptosis, as did chelation of extracellular Ca(2+). Finally, while TRPV1 and TRPV4 co-localize in some RGC bodies and form a protein complex in the retina, expression of their mRNA is inversely related with increasing ocular pressure. We propose that TRPV1 activation by pressure-related insult in the eye initiates changes in expression that contribute to a Ca(2+)-dependent adaptive response to maintain excitatory signaling in RGCs.
Keywords: CAP, capsaicin; EGTA, ethyleneglycol-bis(B-aminoethyl)-N, N, N1, N1-tetraacetic acid; IRTX, iodo-resinferatoxin; TRPV1; TRPV1, transient receptor potential vanilloid-1; TRPV4; TRPV4, transient receptor potential vanilloid-4; TUNEL, terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling).; glaucoma; mechanosensation; neurodegeneration; optic nerve; retina; retinal ganglion cell.