INFLUENCE OF METHIONINE-ENKEPHALIN ON STRESS-INDUCED PARAMETERS

This study examines the influence of methionine-enkephalin (MENK) on s tress-induced oxidative damage (lipid peroxidation; LPO) in mice liver homogenate, plasma corticosterone concentration (CS) and phagocytic a ctivity of mouse splenocytes. The LPO value increased in the mice subj ected to restraint stress and had no correlation to stress duration, w hile MENK had no effect. The CS concentration was enhanced after 6 h o f stress and 6 h after injection of a low (2.5 mg/kg bw) dose of MENK. However, MENK and stress are adjunct modulators of LPO and corticoste rone in vivo. LPO was additionally elevated when MENK (10 mg/kg bw) pr oceeded for 2 h after the onset of stress. However, corticosterone con centration seems to be regulated differently by the same dose of MENK depending on the duration of stress i.e. elevated in cases involving s hort periods of stress (2 h) and decreased in cases involving prolonge d periods of stress (6 h). This modulation of LPO and corticosterone b y 10 mg/kg bw of MENK and 2 h of restraint stress was paralleled with elevated phagocytosis. (C) 1998 International Society for Immunopharma cology.