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We studied the effect of Selank administered intraperitoneally in doses of 100, 300, and 1000 μg/kg to male Wistar rats 15 min prior to restraint stress on the content of aminotransferases and total protein concentration in blood serum and intensity of free radical oxidation in the liver. Under conditions of acute restraint stress, Selank in doses of 100 and 300 μg/kg decreased catalase and superoxide dismutase activities and malondialdehyde concentration and increased total antioxidant activity in the liver homogenate. Administration of Selank in a dose of 1000 μg/kg reduced the content of aminotransferases in blood serum, decreased superoxide dismutase activity in the liver, and increased total antioxidant activity. Under conditions of chronic stress, Selank in all doses produced similar effects: reduced superoxide dismutase activity and malondialdehyde concentration in the liver tissue and AST activity in the serum. The other parameters remained unchanged.

We studied the effect of intraperitoneal administration of peptide ACTG 4-7 -PGP to male Wistar rats in doses of 5, 50, 150, and 450 μg/kg on the morphofunctional state of hepatocytes in chronic emotional and painful stress. A dose-dependent stress-limiting effect of the peptide was observed: it normalized the protein synthesis function of the liver and serum activity of ALT. The anticytolytic effect of the peptide increased with increasing its dose against the background of the increase in the relative number of multinucleated and multinucleolated cells and deceleration of the recovery of serum protein concentration. The decrease of hepatocyte cytolysis against the background of more intense morphological signs of protein synthesis processes attests to activation of reparative processes in the liver parenchyma via enhanced constitutional synthesis of protein.

We studied the effect of delta sleep-inducing peptide (40, 120, and 360 μg/kg intraperitoneally, 1 h before the experiment) on free radical oxidation in the liver, aminotransferase activity, and total serum protein content in male Wistar rats during restraint stress. Treatment with the peptide in a dose of 40 μg/kg increased catalase and superoxide dismutase (SOD) activities and malonic dialdehyde (MDA) concentration in the liver homogenate of animals subjected to acute stress. No significant changes were found after administration of this peptide in other doses. Under conditions of chronic stress, the peptide in a dose of 40 μg/kg caused the most pronounced effect. Catalase and SOD activities and MDA concentration decreased, while aminotransferase activity and protein content remained unchanged under these conditions. Administration of the peptide in a dose of 120 μg/kg was accompanied by a decrease in SOD activity and MDA concentration, increase in total protein content, and reduction of AST activity. Increasing the peptide dose to 360 μg/kg abolished its effects.

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.

The effect of ACTH4-7-PGP (Semax) intraperitoneal injection at the doses of 5, 50, 150 and 450 μg/kg b. w. on lipid peroxidation and functional hepatocytes state in Wistar male rats subjected to acute and chronic electrical foot-shock stress was investigated. It was observed that peptide at the doses of 50 and 450 μg/kg normalized malondialdehyde (MDA) level elevation in the liver homogenate caused by acute foot-shock stress. On the contrary, at the doses of 5 and 150 μg/kg Semax significantly increased MDA content without essential changes of antioxidant defense activity (catalase, superoxide dismutase, common antioxidative activity). In serum peptide at the all doses decreased stress-induced asparate aminotransferase activity elevation. In chronic stress peptide provided the normalization of protein synthetic hepatocytes function and the serum alanine aminotransferase activity with less effect on lipid peroxidation.