Eye drops of PNU-282987, an α7 nicotinic acetylcholine receptor agonist, were shown to support regeneration of retinal neurons in mice. In this study, photoreceptor cell degeneration was mimicked in a glaucoma model and a transgenic Müller-glia lineage tracer was introduced into mice. For the mice with induced glaucoma-like conditions PNU-282987 treatment led to new formation of neurons connecting to the optic nerve as a result of Müller glia cell activation. It is theorized that with treatment of PNU-282987, “Müller glia cells re-enter the cell cycle to produce progenitor-like cells that can differentiate into various types of retinal neurons”. For mice with induced photoreceptor damage, treatment of PNU-282987 led to regeneration of both rods and cones.
What this means for Usher syndrome: Patients with USH typically have retinitis pigmentosa (RP), which causes degenerative loss of photoreceptor cells in the retina. Müller-glia cells are an integral component of the retinal structure to support light perception. Müller cells in mammals do not have the ability to regenerate; if there is continued research demonstrating successful neural cell regeneration then there is potential that an α7 nAChR could be used as a treatment for RP in Usher syndrome.