The effect of a-melanocyte stımulatıng hormone on burn-ınduced oxıdant productıon by rat perıtoneal neutrophıls
Oktar, Berna K.
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Objective: Previous findings related to the antiinflammatory effects of a-melanocyte stimulating hormone (a-MSH) indicate that the peptide might inhibit inflammation by antagonizing the effects of local cytokines or by inhibiting neutrophil functions. In addition, it is a potent inhibitor of the induction of the inducible nitric oxide synthase (¡NOS) in cultured macrophages and of nitric oxide (NO) production in a sepsis model. This study was designed to investigate whether a-MSH affects reactive oxygen metabolite production by rat peritoneal neutrophils following burn injury and whether NO is involved in this effect. Methods: The neutrophils were removed from the peritoneum of the rats 6 h after burn or sham trauma. Cells (2 X 106 /ml) were treated with the increasing concentrations of a-MSH (10-12 M, 10-10 M, 10-8 M or 10-6 M). Nitric oxide donor, sodium nitroprusside ranging from (10~10 - 10^ M) was added to the cells in the presence of a- MSH. Reactive oxygen metabolite production was measured by chemiluminescence (CL) technique using luminol or lucigenin probes. Results: Lucigenin CL value of cells obtained from burn animals was significantly higher than those obtained from the sham group. a-MSH caused significant reductions in high lucigenin CL values and this effect was partly inhibited by sodium nitroprusside. Conclusion: Our results suggest that a-MSH is effective in preventing oxidant production by neutrophils activated by burn trauma, at least in part, by a mechanism involving nitric oxide.