Regulation of free radical processes by delta-sleep inducing peptide in rat tissues under cold stress

An intraperitoneal injection of an exogenous delta-sleep inducing peptide ( DSIP) at a dose of 12 mug/100 g body weight shifted the prooxidant-antioxid ant balance of free radical process (FRP) in tissues and erythrocytes of ra ts: the activities of antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase) and the concentrations o f antioxidants (reduced glutathione in particular) increased. The DSIP stim ulated the myeloperoxidase activity in blood neutrophils and had no effect on the activity of xanthine oxidase, a prooxidant enzyme, in the brain and liver. Cold stress displaced the prooxidant-antioxidant balance by increasi ng the xanthine oxidase activity in tissues and decreasing the myeloperoxid ase activity in blood neutrophils; it also inhibited the enzyme antioxidant activities in tissues and erythrocytes that was neutralized by an increase d ceruloplasmin activity in blood plasma and by an elevated level of antiox idants in rat blood and tissues. Preliminary administration of DSIP to anim als exposed to cold stress restored the prooxidant-antioxidant balance: it normalized the myeloperoxidase activity in blood neutrophils, decreased the xanthine oxidase activity, and increased the activity of antioxidant enzym es in tissues and erythrocytes restoring the antioxidant level. The molecul ar regulation mechanism of free radical processes by DSIP in tissues under stressful conditions is discussed.