Binding of Glyprolines to L-Arginine Inverts Its Analgesic and Antiagressogenic Effects

We studied the effects of intraperitoneal administration of L-arginine in doses of 5, 15, and 50 μg/kg and peptides in doses containing equimolar amount of this amino acid on aggressive-defensive behavior of rats (footshock model). The peptides were synthesized by binding of Pro-Gly-Pro sequence to one or both ends of the L-arginine molecule. The analgesic and antiagressogenic effects of L-arginine and opposite effects of arginine-containing peptides (except Pro-Gly-Pro tripeptide) were demonstrated. The combination of arginine with glyprolines yielded peptides with intrinsic regulatory properties. This expands the possibilities of synthesis of drugs for correction of pain and aggression caused by pain.