Buspirone is protective against oxidative stress induced changes in cell culture and animal models of RPE oxidative injury

Abstract

Purpose : Preservation of central vision is an unmet clinical need in dry age-related macular degeneration (AMD). Chronic oxidative stress impairs the normal functioning of RPE and causes RPE atrophy, leading to loss of macular photoreceptors. The purpose of our study is to determine if buspirone, a partial 5-HT1A agonist receptor agonist, is protective against oxidative stress-induced changes in the RPE.

Methods : The effect of buspirone was evaluated in the sodium iodate model (NaIO₃) of RPE oxidative injury and paraquat-induced oxidative damage in differentiated human ARPE-19 cell culture model. Protection of RPE and photoreceptors in NaIO₃-treated C57BL/6J mice with or without buspirone treatment was characterized by the preservation of outer nucleal layer thickness (mean ± standard error of mean), measured by spectral-domain optical coherence tomography (SD-OCT). RPE/choroid from mice was analyzed by ZO-1 (a phosphoprotein present at tight junctions) and immunostaining of RPE flat-mounts. Quantitative RT-PCR was performed to investigate the effect of buspirone on inducing the expression level of protective enzymes. In response to paraquat-induced cellular toxicities and RPE junctional abnormalities in ARPE-19 cells, the impact of buspirone was assessed by MTT assays and ZO-1 immunocytochemistry, respectively.

Results : Daily intraperitoneal injection (i.p.) of buspirone (30mg/Kg) for 12 days mitigated the thinning of the outer nuclear layer (p<0.0001) in the NaIO₃ model (88.04µm ± 8.009, n=12) compared to vehicle treated eyes (32.83 µm ± 3.861, n=10) determined by SD-OCT. Fluorescent images of RPE flat-mounts stained with ZO-1 tight junction protein revealed the structural preservation of RPE from oxidative damage in buspirone treated mice. Furthermore, buspirone treatment showed an increased trend of expression of key cytoprotective antioxidant genes (Nqo1, Cat, Sqstm1, Gstm1, and Sod2) in the RPE/choroid compared to untreated eyes. MTT assay showed dose-dependent protection of viability in buspirone-treated ARPE-19 cells in culture and preservation of RPE junctional integrity in differentiated ARPE-19 cells in response to paraquat-induced cellular toxicities.

Conclusions : Buspirone provided structural protection of RPE cells from oxidative injury by inducing antioxidant survival pathway. As an FDA-approved drug, repurposing buspirone may be useful in treating dry-AMD.

This is a 2021 ARVO Annual Meeting abstract.