Apomorphine-induced aggressive behaviour in para-chlorophenylalanine-treated male rats: implications to brain

The aim of this study was to investigate the role of serotoninergic neurotransmission and the effect of acute para-chlorophenylalanine (350 mg/kg, intraperitoneally) treatment on apomorphine-induced aggressive behaviour in adult male Wistar rats. In addition, [3H]ketanserin binding and monoamine content were studied. Repeated administration of apomorphine (1.0 mg/kg, subcutaneously, once daily for two weeks) gradually induced aggressive behaviour. Acute p-chlorophenylalanine treatment down-regulated the [3H]ketanserin binding and reduced over 90 per cent the content of serotonin and 5-hydroxyindolacetic acid. In a half of the p-chlorophenylalanine-treated animals, the aggressive behaviour was suppressed, while there was no difference in [3H]ketanserin binding or monoamine content between the p-chlorophenylalanine treated aggressive and non-aggressive animals. In conclusion, the acute p-chlorophenylalanine treatment attenuates the aggressiveness only in half of the animals, while the latter phenomenon is independent on the CNS monoamine content or [3H]ketanserin binding.