Effect of tryptophan administration on spontaneous and p-CPA-induced muricidal aggression in laboratory rats

Summary Muricidal activity, by which some strains of rats stereotypically kill mice, can be induced in laboratory rats by surgical, pharmacological or environmental manipulations, which consistently impair serotonergic transmission in the brain of treated animals in a variety of ways. Manipulations of tryptophan intake result in either facilitation or reduction of spontaneous muricidal activity in rats. In this framework, p-CPA inducesmuricidal activity in naive laboratory rats, even against any genetic predisposition, and orally-administered 1-tryptophan is shown to inhibit p-CPA-induced muricidal aggression.