CHARACTERIZATION OF THE REACTIVE GLIOSIS IN THE RETINAS OF THE 5XFAD MOUSE MODEL OF ALZHEIMER'S DISEASE

Alzheimer's disease (AD) is characterized primarily by profound cognitive deficits and dementia. A key feature of AD is neuronal loss accompanied by the deposition of amyloid beta and hyperphosphorylated Tau in the brain. However, the effects of AD are not limited to the brain but also affect other regions of the central nervous system, including the retina. Alterations in visual perception in AD were initially attributed to defects in the brain's processing of visual images. Still, later studies revealed structural changes and inflammation in the retinas of AD patients and animal models. Here, we aimed to characterize microgliosis and macrogliosis in retinas of the 5xFAD mouse model of AD at late stages of the disease (1 year), comparing them to age-matched wild type (WT) retinas. Flat-mounted retinas were immunostained for IBA1 and for GFAP to detect microglia and astrocytes, respectively. The central, medial, and peripheral retinas were analyzed employing confocal microscopy. We observed increased IBA1+ cells in AD retinas, compared with WT. This increase was specific to the central and peripheral areas of the inner plexiform layer and was not observed in the outer plexiform layer. Also, we observed increased GFAP immunostaining in the ganglion cell layer in AD retinas. This increase took place in all the regions analyzed. Müller glia, the main glial population in the retina, was also activated in AD retinas, especially in the periphery. Our data show increased macro- and microgliosis in the retinas of 5xFAD mice, underscoring the importance of retinal pathology in AD.