Effects of Tripeptide Gly-His-Lys in Pain-Induced Aggressive-Defensive Behavior in Rats

We studied the effect of Gly-His -Lys tripeptide administered intraperitoneally in doses of 5, 15, 50 and 150 μg/kg on pain-induced aggressive-defensive behavior. A foot-shock model of aggression in rats grouped in pairs in an electrified chamber was used. Analgesic and antiaggresiogenic effects of the peptide were demonstrated. It was found the L-lysine residue plays the key role in these effects, because they were observed under the influence of L-lysine administration in doses close to its equimolar content in the studied tripeptide.