PT  - JOURNAL ARTICLE
AU  - Xu Wang
AU  - Lian Zhao
AU  - Yikui Zhang
AU  - Wenxin Ma
AU  - Shaimar R. Gonzalez
AU  - Jianguo Fan
AU  - Friedrich Kretschmer
AU  - Tudor C. Badea
AU  - Hao-hua Qian
AU  - Wai T. Wong
TI  - Tamoxifen Provides Structural and Functional Rescue in Murine Models of Photoreceptor Degeneration
AID  - 10.1523/JNEUROSCI.2717-16.2017
DP  - 2017 Mar 22
TA  - The Journal of Neuroscience
PG  - 3294--3310
VI  - 37
IP  - 12
4099  - http://www.jneurosci.org/content/37/12/3294.short
4100  - http://www.jneurosci.org/content/37/12/3294.full
SO  - J. Neurosci.2017 Mar 22; 37
AB  - Photoreceptor degeneration is a cause of irreversible vision loss in incurable blinding retinal diseases including retinitis pigmentosa (RP) and atrophic age-related macular degeneration. We found in two separate mouse models of photoreceptor degeneration that tamoxifen, a selective estrogen receptor modulator and a drug previously linked with retinal toxicity, paradoxically provided potent neuroprotective effects. In a light-induced degeneration model, tamoxifen prevented onset of photoreceptor apoptosis and atrophy and maintained near-normal levels of electroretinographic responses. Rescue effects were correlated with decreased microglial activation and inflammatory cytokine production in the retina in vivo and a reduction of microglia-mediated toxicity to photoreceptors in vitro, indicating a microglia-mediated mechanism of rescue. Tamoxifen also rescued degeneration in a genetic (Pde6brd10) model of RP, significantly improving retinal structure, electrophysiological responses, and visual behavior. These prominent neuroprotective effects warrant the consideration of tamoxifen as a drug suitable for being repurposed to treat photoreceptor degenerative disease.SIGNIFICANCE STATEMENT Photoreceptor degeneration is a cause of irreversible blindness in a number of retinal diseases such as retinitis pigmentosa (RP) and atrophic age-related macular degeneration. Tamoxifen, a selective estrogen receptor modulator approved for the treatment of breast cancer and previously linked to a low incidence of retinal toxicity, was unexpectedly found to exert marked protective effects against photoreceptor degeneration. Structural and functional protective effects were found for an acute model of light-induced photoreceptor injury and for a genetic model for RP. The mechanism of protection involved the modulation of microglial activation and the production of inflammatory cytokines, highlighting the role of inflammatory mechanisms in photoreceptor degeneration. Tamoxifen may be suitable for clinical study as a potential treatment for diseases involving photoreceptor degeneration.