Retinal microglial activation in a SOD1 mouse model of ALS

Abstract

PurposeTo determine the differences in retinal microglial behaviour in a SOD1G93A mouse model (SOD) of amyotrophic lateral sclerosis (ALS) compared to the wild type (WT).MethodsIn retinal whole‐mounts labelled with anti‐Iba‐1 (microglial marker) from two experimental groups WT (n = 6) and SOD ALS (n = 6), signs of microglial activation were quantified in different retinal layers: (i) Iba‐1 + cells number in outer segments (OS), outer plexiform layer (OPL) and inner complex layer (ICL) constituted by inner plexiform layer (IPL), ganglion cell layer (GCL) and retinal nerve fiber layer (RNFL); (ii) cell area of Iba‐1+ cells in OPL and IPL; (iii) arbor area of Iba‐1+ cells in OPL and IPL. Animals were sacrificed with 120 days old.ResultsCompared to WT, the retina of SOD1 ALS mice showed: (i) Migrations and reorientation processes of some Iba‐1 + cells; (ii) A significant increase in the Iba‐1 + cell area in OPL (in inferior, nasal, temporal regions and total number) and in the total number in IPL; (iii) A significant increase in the arbor area in the inferior OPL region; (iv) No significant changes were observed in the number of Iba‐1 + cells in OS, OPL and ICL.ConclusionsThese findings demonstrate a non‐proliferative microgliosis in SOD1‐ALS mice retinas. The microglial activation was higher in OPL, which could be related to an increased inflammatory process in this retinal layer. Although ALS is a motor neuron disease, it can also affect the retinal tissue where an inflammatory process takes place.