SBNeC 2010
Resumo:B.045


Poster (Painel)
B.045Relationship Between the Proteins S100B and Aquaporin-4
Autores:Caroline Zanotto (UFRGS - Universidade Federal do Rio Grande do Sul) ; Renata Torres Abib (UFRGS - Universidade Federal do Rio Grande do Sul) ; Lucas Silva Tortorelli (UFRGS - Universidade Federal do Rio Grande do Sul) ; Cristiane Batassini (UFRGS - Universidade Federal do Rio Grande do Sul) ; Maria Cristina Guerra (UFRGS - Universidade Federal do Rio Grande do Sul) ; Marina Concli Leite (UFRGS - Universidade Federal do Rio Grande do Sul) ; Carmem Gottfried (UFRGS - Universidade Federal do Rio Grande do Sul) ; Carlos Alberto Gonçalves (UFRGS - Universidade Federal do Rio Grande do Sul)

Resumo

Objective: S100B is a calcium binding protein produced and secreted by astrocytes, which has paracrine neurotrophic activity when expressed in order of nM and neurotoxic activity at µM levels. It has been proposed that oxidative stress caused by overexpression of S100B in Down’s syndrome results in a compensatory increase in the cytoprotective protein aquaporin-4 (AQP4). However, a functional interaction between these proteins was not investigated. Herein, we evaluated the secretion of S100B in acute hippocampal slices from Wistar rats incubated with inhibitors of protein AQP4. Materials and Methods: We prepared acute hippocampal slices of 15 days old rats (n=6), which were incubated in oxygenated physiological medium that were changed every 15 min with fresh medium during 2 h for stabilization. After these, slices were incubated for 1 h with tetraethylammonium chloride (10, 100 and 1000 µM), acetazolamide (1, 10 and 100 µM) or vehicle DMSO (0.1%). The secretion of S100B was measured by ELISA and cell viability was evaluated by MTT assay. Results: The hippocampal slices incubated with tetraethylammonium chloride in the concentration of 10, 100 and 100 µM showed an increase of 150% ± 8.4, 159.3% ± 12.3 and 174% ± 24.8%, respectively (p<0.05), in the S100B secretion. However, in the slices incubated with acetazolamide, only the two highest concentrations tested caused a significant increase in S100B secretion (191.2% ± 18.6 and 214.4% ± 21.5, respectively at p<0.05). No changes in MTT reduction assay were induced in treated slices. Statistical analysis was performed by one way analysis of variance (ANOVA) followed by Tukey’s post hoc test. Conclusion: These data suggest that S100B secretion may be modulated by protein AQP4 activity, since the presence of AQP4 inhibitors increase S100B secretion. Furthermore, S100B released could be protective during AQP4 inhibition. This study may contribute to understanding of the mechanism of S100B secretion.


Palavras-chave:  Astrocytes, S100B, Aquaporin-4, hippocampal slices