para-Chloro-D, L-phenylalanine induced filicidal behavior in the female rat

The administration of para-chloro-D, L-phenylalanine (PCPA) produces a high incidence of aggressive (filicidal) behavior in pre-, postpartum, and nulliparious rodents. PCPA inhibits brain tryptophan 5-monooxygenase and can produce a reduction in whole brain serotonin. Apparently PCPA mediates the release of a natural latent aggressive tendency which is potentiated by the interference in, or reduction of, a suppressing system governed by serotonin. Latency of attack, intensity phases, and characteristics of the filicidal behavior were found to vary inversely with brain serotonin content, and be reversed or eliminated by replacement of serotonin i.e., via 5-hydroxytryptophan, serotonin's immediate precursor. Although aggressive tendencies were in evidence prior to filicide, filicide became evident once the apparently minimal whole brain level of serotonin reached ca 0.10 microgram/g. Neither the parturition process nor severe food deprivation are strong causative factors in the precipitation of filicidal behavior. Since not all animals become filicidal, other behavioral and/or biological variables must be involved in the mediation of this aggressive phenomenon.