Facilitation of shock-induced fighting in the rat after DSP-4, a selective noradrenergic neurotoxin.

Rats treated with DSP-4 showed a marked enhancement of shock-induced fighting (SIF). Administration of 1-propranolol attenuated or completely counteracted SIF in control animals, but only the highest dose (10 mg/kg) of this beta-adrenergic antagonist was effective in reducing SIF in DSP-4 animals. Other behavioral experiments indicated that the responsiveness of DSP-4 rats to dopaminergic, serotoninergic, and cholinergic agonists was unchanged compared to that of control rats. The results confirm the participation of the noradrenergic system in SIF, and substantiate an involvement of beta-adrenergic receptors in this kind of aggression.