engleski

In vivo enhancement od cytotoxic activity of mouse peritoneal macrophages by Met-enkephalin

Met-enkephalin modulates several functions of macrophages in vitro by binding to opioid receptors expressed on them. However, there is a paucity of data on its ability to alter macrophages function in vivo. In this study, we examined the effect of single systemic i.p. injection of Met-enkephalin (MENK) into CBA mice on the cytotoxic activity and NO secretion of peritoneal macrophages. Involment of opioid receptors in the MENK actions was tested by using opioid receptor antagonist, naloxon (Nx). MENK significantly enhanced cytotoxic activity of peritoneal macrophages. This was associated with enhanced NO production. MENK induced effects were completely (NO release) or partly (cytotoxicity) reversed by naloxone (10mg/kg). However, naloxone by itself acted as an agonists, enhancing macrophage cytotoxicity. Lower Nx doses (2.5 and 5mg/kg) had lower agonistic activity, but were inactive with regrad to the antagonistic ability. The necessity for relatively high naloxone concentration for the reversion of the MENK induced enhancement of macrophages cytotoxicity suggests involment of delta opioid receptors.

met-enkephalin; nitric oxides; peritoneal macrophages; cytotoxicity

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