Melatonin protects the retina from experimental non-exudative age-relatd macular degeneration in mice

Abstract

Abstract: Non-exudative age-related macular degeneration (NE-AMD) represents the leading cause of blindness in the elderly. Currently, there are no available treatments for NE-AMD. We have developed a NE-AMD model induced by superior cervical ganglionectomy (SCGx) in C57BL/6J mice, which reproduces the disease hallmarks. Several lines of evidence strongly support the involvement of oxidative stress in NEAMD- induced retinal pigment epithelium (RPE) and outer retina damage. Melatonin is a proven and safe antioxidant. Our aim was analyzing the effect of melatonin in the RPE/outer retina damage within experimental NE-AMD. The treatment with melatonin starting 48 h after SCGx, which had no effect on the ubiquitous choriocapillaris widening, protected visual functions, and avoided Bruch´s membrane thickening, RPE melanin content, melanosome number loss, retinoid isomerohydrolase (RPE65)- immunoreactivity decrease, and RPE and photoreceptor ultrastructural damage induced within experimental NE-AMD exclusively located at the central temporal (but not nasal) region. Melatonin also prevented the increase in outer retina/RPE oxidative stress markers, and a decrease in mitochondrial mass at 6 weeks post-SCGx. Moreover, when the treatment with melatonin started at 4 weeks post-SCGx, it restored visual functions and reversed the decrease in RPE melanin content and RPE65-immunoreactivity. These findings suggest that melatonin could become a promising safe therapeutic strategy for NE-AMD.