To further investigate one of the possible mechanisms involved on neuroprotective effect of GM1 just reported, we analyzed GM1 effect

upon Aβ induced alteration in GSK3β phosphorylation after 1, 6, 12 and 24 h. Results show no effect of GM1 or fibrillar Aβ25–35 treatment after 1 h of treatment. Nevertheless, 6 h of co-treatment with GM1 and Aβ25–35 caused a significant increase in GSK3β phosphorylation. After 12 h of GM1 treatment we observed a decrease (p < 0.05) in GSK3β phosphorylation, and after 24 h of treatment it was shown that GM1 was able to augment GSK3β phosphorylation; moreover the co-treatment with GM1 and Aβ25–35 was see more able to prevent β-amyloid-induced reduction in GSK3β phosphorylation state ( Fig. 4). Organotypic cultures, in spite of some limitations, are a good alternative to in vivo models, since they provide a good experimental access to mimic pathophysiological pathways in living tissues, and because they preserve the cell organization and tissue architecture ( Stoppini et al., 1991, Tavares et al., 2001, Holopainen, 2005, Cimarosti et al., 2006, Horn et al., 2009,

Simão et al., 2009 and Hoppe et al., 2010). Using this model, we could observe that the Aβ induced death depended on its aggregation state, since the non-fibrillar peptide form was unable HA-1077 research buy to trigger toxicity, or at least the toxicity as measured by PI uptake protocols ( Fig. 1). Even though the main limitation observed in this in vitro technique is the variation, which is inherent in this model, we believe in the reliability of our results, since we performed the experiments comparing the effect of Aβ-peptide and/or the effect of GM1, using slice culture of the same animal. Nevertheless our results Mannose-binding protein-associated serine protease showed strong toxic effect of Aβ and a notable neuroprotective effect of GM1. Taking into account a considerable number of studies suggesting a role of gangliosides and membrane lipid dynamics in the amyloid cascade modulation, as well as a participation of these lipids in the toxicity mechanisms triggered by amyloid peptide, the present study has investigated the effect

of Aβ25–35, in its fibrillar or non-fibrillar forms, upon ganglioside expression in a model of hippocampal organotypic cultures (Yanagisawa, 2007, Ariga et al., 2008, Zhang et al., 2009, Eckert et al., 2010, Harris and Milton, 2010 and Haughey et al., 2010). Our results firstly demonstrate an Aβ25–35 effect on ganglioside expression, which seemed to depend on the peptide aggregation state. Whereas fibrillar Aβ25–35 caused an increase in GM3 and a decrease in GD1b metabolic labeling, its non-fibrillar form was able to enhance GM1 expression (Fig. 2B and C). Considering that GM3 is a ganglioside usually associated with apoptotic mechanisms, at least when expressed in mature neuronal cells (Sohn et al., 2006 and Valaperta et al., 2006), and taking into account an anti-apoptotic effect attributed to GD1b (Chen et al.