Effect of Selank on Morphological Parameters of Rat Liver in Chronic Foot-Shock Stress.

We studied the effects of Selank on morphological parameters of the liver in Wistar male rats subjected to chronic foot-shock stress. Selank was injected intraperitoneally in doses of 100, 300 and 1000 µg/kg 15 min before each stress session. Morphological and morphometrical analysis showed that chronic foot-shock stress induced hydropic degeneration of hepatocytes, an increase of the nucleus/cytoplasm ratio due to an increase in the area of nuclei and reduction of the cytoplasm area, the appearance of focal necroses, and lymphohistiocyte infiltration. Injection of Selank in all doses reduced the intensity of stress-induced degenerative changes. Administration of Selank in doses of 300 and 1000 µg/kg restored the nucleus/cytoplasm ratio in hepatocytes. The maximum stress-limiting effect was attained after administration of 300 µg/kg Selank.

Effect of Delta Sleep-Inducing Peptide on Functional State of Hepatocytes in Rats During Restraint Stress.

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 INFLUENCE OF DELTA SLEEP-INDUCING PEPTIDE ON FUNCTIONAL STATE OF RATS HEPATOCYTES IN FOOT-SHOCK STRESS].

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 peptide ACTH4-7-PGP on functional hepatocyte state in rats in acute and chronic foot-shock stress].

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.

Anxiolytic effects of Gly-His-Lys peptide and its analogs.

Intraperitoneal administration of tripeptide Gly-His-Lys to male rats in doses of 0.5, 5, and 50 µg/kg 12 min before the start of the experiment produced an anxiolytic effect in the elevated plus maze test manifested in an increase in the time spent in open arms and shortened time spent in the closed arms. The anxiolytic effect was most pronounced after injection of 0.5 µg/kg peptide and decreased with increasing the dose of the peptide. Replacement of L-lysine with D-lysine in the tripeptide molecule was accompanied by a significant weakening of the neurotropic effects in all studied doses. Attachment of D-alanine to N- or C-terminus of Gly-His-Lys peptide leveled its anxiolytic action in all doses; significant changes in some measures of increased anxiety after administration at 50 µg/kg were found.

[Effect of Gly-His-Lys peptide and its analogs on pain sensitivity in mice].

The intraperitoneal administration of Gly-His-Lys tripeptide to male BALB/c mice 12 min before the beginning of the study at doses 0.5, 1.5, 5, 15, and 50 mg/kg produced analgesic effect in the hot-plate test, which was manifested by an increase in the duration of the latent period of the paw-licking reaction. The replacement of L-lysine by D-lysine in the tripeptide molecule was accompanied by significant weakening of the analgesic effect after administration in the same doses. The attachment of D-alanine to N- or C-end of Gly-His-Lys peptide led to leveling of the analgesic effect. On the contrary, after the administration of these analogs, the duration of the latent period of the paw-licking reaction was increased in almost all experimental groups of animals and reached in some cases significant differences that were indicative of the manifestation of algic effects of the modified peptides.