Resumo

OBJECTIVES: Glial cells are key elements on development and regeneration of the CNS and are able to produce and respond to cytokines. Müller cells, the predominant glia in the retina, synthesize and respond to many signaling molecules. During the development and following different injury, these cells up-regulate glial fibrillary acidic protein (GFAP) which has been associated with a switch to an activated state. Interleukin-4 is an anti-inflammatory cytokine related to hippocampal neuronal survival and differentiation and proliferation of retinal cells. In retina IL-4 receptor was identified both in photoreceptors and Müller cell process. The aim of this work was to study the expression of glial fibrillary acidic protein (GFAP) in animals subjected to intravitreous administration of IL-4. METHODS: Lister Hooded rats received intravitrous IL-4 or PBS (vehicle) injections in the right eye at PND10. At PND14 the animals were sacrificed, retina extracted and processed for western blot analysis to verified GFAP content. Cyclophilin was used as a loading control. RESULTS: Our data showed the presence of GFAP in PBS-treated retinas. This level is similar to our previously data for untreated retinas (Espírito-Santo et al., 2008 – Neurolatam). Conversely, after an acute IL-4 treatment, animals presented a robust decrease in GFAP content when compared to PBS-treated retinas. CONCLUSION: Our results indicate that GFAP expression is down-regulated by interleukin-4 in the visual system. Previously we had demonstrated that interleukin-2 increase GFAP levels. Taken together, these data support the hypothesis that glial reactivity is differentially modulated by inflammatory and anti-inflammatory cytokines, which have been associated to different pathological conditions in the central nervous system, including retina diseases. FINANCIAL SUPPORT: PROPPi-UFF, PIBIC-UFF, CNPq, FAPERJ, PROAP-UFF