Abstract
Purpose: :
The role of microglia during retinal degeneration is little characterized. We studied the distribution of microglia in the rd10 mouse retina, a model of Retinitis Pigmentosa, as well as its possible involvement in photoreceptor rescue displayed by IGF-I (Arroba et al., 2009, Eur. J. Neurosci. 30, 975).
Methods: :
The distribution of microglia within retinal layers in the Pde6brd10 mouse was determined by immunolabeling with IBA-1 (activated microglia) and CD11-b (resting microglia) antibodies. Ex vivo retinal explants were used to analyze modulation of microglia distribution by IGF-I, as well as IGF-I effect on photoreceptor cell death, as determined by TUNEL. Depletion of microglia in explant culture was achieved by treatment with liposomes containing clodronate.
Results: :
Microglia showed an altered distribution in rd10 retinas in comparison with wild type retinas. In rd10 retinas, higher numbers of activated microglia cells were found in the OPL than in wild type retinas. IGF-I treatment of rd10 retinas induced a further increase in the number of activated microglia cells, as well as a decrease in photoreceptor cell death. Depletion of microglia prevented the neuroprotective effect displayed by IGF-I.
Conclusions: :
In light of these findings, microglial cells seem to respond to retinal degeneration and appear to play a critical role in mediating the neuroprotective effect of IGF-I.
Keywords: microglia • retinitis • neuroprotection