Resumo

Objectives: Eph/ephrin signaling-mediated cell communication plays important roles during nervous system (NS) development. Although generally down-regulated in most areas of the adult central NS, Eph and ephrin molecules are regulated following nervous injury, in which they might participate in the glial cellular communication-related to neuroimmunemodulation, inflammation, wound repair and paracrine trophic events. Amyotrophic Lateral Sclerosis (ALS) is an adult-onset and fast progression neurodegenerative disease that leads the loss of motor neurons. Familial ALS is manly linked to dominant mutations in the gene for Cu/Zn superoxide dismutase (SOD1). Toxic signs from non neuronal cells, especially those from astrocytes and microglia, have been proposed to be involved in the rapid evolution of the disease based on evidences from in vitro studies. Thus, Eph/ephrin system may be involved in the mechanism of motor neuron damage in the spinal cord of SOD1 mutant mice. Methods: Lumbar spinal cords of transgenic mice in the end-point of disease and age-paired wild type controls were processed for single and two-color immunohistochemistry and Western Blotting. In order to evaluate cellular presence and protein levels of ephrins B1, B2, B3 and the ephrin receptor EphB1. Apoptosis was evaluated by means of Bax regulation and TUNEL. Results: Increased amounts Bax (0.92 ± 0.08; 2.62 ± 0.22, p<0.0001), ephrin B2 (2.23 ± 0.34; 6.04 ± 0.49, p<0.0001) and ephrin B3 (5.97 ± 0.37; 7.93 ± 0.49, p<0.05) and diminution of ephrin B1 (13.57 ± 1.30; 8.70 ± 0.66, p<0.01) were found in ALS mice comparing to wild type. No change has been detected in the levels of receptor EphB1 (6.19 ± 0.61; 6.41 ± 0.48). Cellular analysis showed increased labeling of Bax, studied ephrins and the receptor EphB1 in reactive astrocytes which massively infiltrate spinal cord ventral horn of mutant mice. TUNEL positive labeling was mainly evidenced in the nuclei of positive astrocytes with atypical morphology as well as in some remaining neurons of that region. Conclusion: Astroglial reaction may use ephrin system to modulate inflammation in ALS. The involvement of the ephrin signalization to neuronal and astroglial death and also for the disease progression are matters of further analyses.