Systemic taurine treatment provides neuroprotection against retinal photoreceptor degeneration and visual function impairments

Objective: Retinitis pigmentosa causes progressive photoreceptor degeneration in the subjects while no clinical therapy exists. The present study sought to evaluate the potential protective effects of taurine on a pharmacologically induced RP animal model. Methods: Photoreceptor degeneration in mice was induced by an intraperitoneal injection of N-methyl-N-nitrosourea (MNU). The MNU-administrated mouse received taurine treatment and then they were examined by electroretinography, spectral-domain optical coherence tomography, optokinetic test, and histological and immunohistochemistry assay. Results: Prominent taurine deficiency was found in the retinas of MNU-administered mice. Intravenous taurine treatment increased significantly the retinal taurine level. Morphological studies showed that taurine could alleviate the retinal disorganizations in the MNU-induced mice. Taurine also ameliorated the visual impairments in the MNU-induced mice as evidenced by functional examinations Immunostaining experiments demonstrated that both the M-cone and S-cone populations in the degenerative retinas are rescued by taurine. In particular, the M-cone photoreceptors in superior-temporal quadrant and the S-cone photo-receptors in inferior-nasal quadrant were preferentially rescued. Mechanism study showed that the photoreceptor apoptosis and oxidative stress in the degenerative retina were effectively alleviated by taurine treatment. Conclusion: Taurine is protective against the MNU-induced photoreceptor degeneration. Systemic taurine administration may act as a promising therapeutic potion for retinopathies with chronic cycle.