The effect of parachlorophenylalanine on the behaviour of cats.

1. Male and female kittens and adult cats were given p-chlorophenylalanine orally.2. After treatment, some of the male cats showed mounting behaviour and the kittens and non-oestrous females showed an increase in treading and rubbing which was similar to one aspect of pro-oestrus behaviour.3. The treated animals also appeared to suffer from skin irritation and showed increased restlessness which accompanied sleep deprivation.4. Injection of 5-hydroxytryptophan stopped abnormal sexual activity and restored normal sleep for about 5 hours.5. It is concluded that 5-hydroxytryptamine-containing neurones inhibit sexual behaviour in cats and that this role can be seen in male and, to some extent, also in female animals.