In rats that were stressed with electric foot shocks, giving the peptide DSIP changed how their liver handled oxidative stress and enzyme activity. A middle dose (120 µg/kg) lowered a damage marker (MDA) after short‑term stress, while low doses raised some blood enzymes. Across all doses, DSIP helped keep liver protein production normal and, during long‑term stress, boosted antioxidant enzymes, but higher doses sometimes increased damage markers.

The effect of delta sleep-inducing peptide (DSIP) intraperitoneal injection in the doses of 40, 120, 360, and 1080 mcg/kg b. w. on lipid peroxidation and functional hepatocyte state in Wistar male rats subjected to acute and chronic electrical foot-shock stress was investigated. It was observed that 120 mcg/kg peptide normalized the elevation of malondialdehyde (MDA) level in the liver homogenate caused by acute foot-shock stress and also significantly decreased catalase activity in all investigated doses. In serum the injection of DSIP up to 40 mcg/kg increased aminotransferase activity. Peptide in all doses provided the normalization of protein synthetic hepatocyte function, increased catalase and superoxide dismutase activity in chronic stress. In addition malondialdehyde content in the liver homogenate was significantly decreased in the dose of 40 mcg/kg and in other cases it was significantly increased against the background of the common antioxidative activity reduction. The stress-induced increase in serum alanine aminotransferase activity was normalized by peptide administration in the doses of 120, 360, and 1080 mcg/kg.