Effects of glyprolines on stress-induced behavioral disorders in rats.

We report here studies on the antistress protective actions of three peptides of the glyproline family: Pro-Gly-Pro, Pro-Gly, and Gly-Pro. Stress (10 min forced swimming) evoked typical changes in the behavioral activity of rats in the elevated cross maze and hole board tests, providing evidence of a significant increase in anxiety and a decrease in the level of orientational-investigative activity. Prior (15 min before stress) i.p. administration of Pro-Gly-Pro and Gly-Pro at a dose of 3.7 microM/kg significantly decreased the stress-induced behavioral abnormalities. This demonstrates the possibility that peptides Pro-Gly-Pro and Gly-Pro may affect CNS structures involved in forming the body's responses to stress-inducing factors. Peptide Pro-Gly, at an equimolar dose, had no marked protective effect and only slightly decreased the stress-induced abnormalities in the behavior of rats.