RESUMO
The immune-suppression caused by acute stress can be reduced by a regular practice of moderate exercise which is known to modulate the expression of secretory-IgA. This antibody is essential for protection against infections and maintenance of homeostasis at the mucosal level. In order to explore the effects of moderate exercise on secretory-IgA production in ileum of the small intestine, 2 groups of mice were submitted to this protocol for 6 months, an exercise group and a sedentary group. After sacrifice, levels of secretory-IgA in intestinal fluid and levels of adrenal hormones in serum were determined by enzyme immunoenzymatic assay. IgA-plasma cells in lamina propria were evaluated by flow cytometry. Transcriptional mRNA expression in mucosa of alpha-chain, J-chain, pIgR and cytokines (Interleukin-2, -4, -6, -10, transforming growth factor-beta, interferon-gamma and tumor necrosis factor) were determined by RT-PCR. In comparison with sedentary mice, moderate exercised mice displayed an up-regulating effect on the production of secretory-IgA and IgA-plasma cells, on the expression of all mRNA transcripts from secretory-IgA associated proteins, and on all cytokines tested. However, serum levels of adrenal hormones were not altered. Future studies on secretory-IgA production are necessary to support the substantive effect of moderate exercise on protection and homeostasis at the intestinal level.