engleski

Macrophage-derived nitric oxide induced in vivo or in vitro by methionine-enkephalin

Opioid peptides are known to modulate immune functions. In this study we have tested the ability of methionine enkephalin (MENK)to induce in vitro or in vivo the release of nitric oxides (NO) from naive or lipopolysaccharide (LPS)stimulated mouse peritoneal macrophages (PEM). We also investigated wether the effect was direct, (opioid receptor mediated) or indirect trough induction of cytokines or hypothalamic-pituitary-adrenal axis (HPA)activation. The obtained results demonstrated that various concentrations of MENK had in vitro no effect on NO release. In vivo only p.m. injection was effective, i.e. the 2.5mg/kg and 10mg/kg of MENK stimulated while 5.0mg/kg of MENK suppressed NO release. The stimulative, but not suppressive effect could be abrogated by naloxone.

Met-enkephalin; nitric oxide; macrophages

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