Behavioral effects of serotonin depletion and of p-chlorophenylalanine (a serotonin depletor) in rats

Comparison of rats given single or multiple injections of p-chlorophenylalanine was used to assess non-serotonergic actions of the drug as well as providing information on the behavioral effects of serotonin (5-HT) depletion.

Abstract

Comparison of rats given single or multiple injections of p-chlorophenylalanine (PCA) was used to assess non-serotonergic actions of the drug as well as providing information on the behavioral effects of serotonin (5-HT) depletion. In Experiment I all groups acquired an active avoidance response in accordance with decreased levels of 5-HT in the CNS and independently of probable PCA or phenylalanine levels. In Experiment II 5-HT depletion facilitated passive avoidance; again, independently of PCA levels. In Experiment III rats were run in an open field for 15 min with or without periods of extra stimulation by intense light or sound. Serotonin-deficient animals were more active than controls under conditions of extra stimulation but slightly less active without extra stimulation. Experiment IV showed that PCA in doses that do not reduce ad libitum drinking can depress quinine intake. It is suggested that 5-HT depletion makes rats more "reactive" to external stimulation.