title: Retinal ganglion cell neuroprotection induced by activation of alpha7 nicotinic acetylcholine receptors.
abstract: The α7nAChR agonist, PNU-282987, has previously been shown to have a neuroprotective effect against loss of retinal ganglion cells (RGCs) in an in vivo glaucoma model when the agent was injected into the vitreous chamber of adult Long Evans rat eyes. Here, we characterized the neuroprotective effect of PNU-282987 at the nerve fiber and retinal ganglion cell layer, determined that neuroprotection occurred when the agonist was applied as eye drops and verified detection of the agonist in the retina, using LC/MS/MS. To induce glaucoma-like conditions in adult Long Evans rats, hypertonic saline was injected into the episcleral veins to induce scar tissue and increase intraocular pressure. Within one month, this procedure produced significant loss of RGCs compared to untreated conditions. RGCs were quantified after immunostaining with an antibody against Thy 1.1 and imaged using a confocal microscope. In dose-response studies, concentrations of PNU-282987 were applied to the animal's right eye two times each day, while the left eye acted as an internal control. Eye drops of PNU-282987 resulted in neuroprotection against RGC loss in a dose-dependent manner using concentrations between 100 μM and 2 mM PNU-282987. LC/MS/MS results demonstrated that PNU-282987 was detected in the retina when applied as eye drops, relatively small amounts of PNU-282987 were measured in blood plasma and no PNU-282987 was detected in cardiac tissue. These results support the hypothesis that eye drop application of PNU-282987 can prevent loss of RGCs associated with glaucoma, which can lead to neuroprotective treatments for diseases that involve α7nAChRs.
authors.affiliation: Western Michigan University, Department of Biological Sciences, Kalamazoo, MI 49008, USA. Electronic address: David_Mata@rush.edu.
authors.forename: David
authors.initials: D
authors.lastname: Mata
authors.affiliation: Grand Valley State University, Department of Biomedical Sciences, Allendale, MI 49401, USA. Electronic address: linnd@gvsu.edu.
authors.forename: David M
authors.initials: DM
authors.lastname: Linn
authors.affiliation: Western Michigan University, Department of Biological Sciences, Kalamazoo, MI 49008, USA. Electronic address: cindy.linn@wmich.edu.
authors.forename: Cindy L
authors.initials: CL
authors.lastname: Linn
mesh_terms: D000818:Animals; D001549:Benzamides / Q000493:pharmacokinetics / Q000494:pharmacology*; D001643:Bridged Bicyclo Compounds / Q000493:pharmacokinetics / Q000494:pharmacology*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004353:Drug Evaluation, Preclinical; D005260:Female; D005901:Glaucoma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D006321:Heart / Q000187:drug effects; D008297:Male; D018613:Microscopy, Confocal; D009206:Myocardium / Q000378:metabolism; D018696:Neuroprotective Agents / Q000493:pharmacokinetics / Q000494:pharmacology*; D009883:Ophthalmic Solutions / Q000493:pharmacokinetics / Q000494:pharmacology; D020318:Rats, Long-Evans; D012165:Retinal Ganglion Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D012462:Saline Solution, Hypertonic; D064569:alpha7 Nicotinic Acetylcholine Receptor / Q000819:agonists* / Q000378:metabolism
chemical_list: D001549:Benzamides; D001643:Bridged Bicyclo Compounds; D018696:Neuroprotective Agents; D009883:Ophthalmic Solutions; C498513:PNU-282987; D012462:Saline Solution, Hypertonic; D064569:alpha7 Nicotinic Acetylcholine Receptor
keywords: Acetylcholine receptors; Adult rats; Glaucoma; Nerve fiber layer; Neuroprotection; Retinal ganglion cells