Failure of tryptophan-free amino acid mixture to modify sexual behavior in the female rat

Female Wistar rats, weekly injected with estradiol valerate after ovariectomy, were trained to cause a sexual contact with a potent male by operating a lever. Contact-response latencies, which vary according to the nature of the sexual contact, were measured as an index of the female's sexual motivation. In these experimental conditions the administration of a tryptophan-free amino acid mixture, which has been proved to decrease brain serotonin and to enhance male mounting behavior, failed to modify the sexual motivation of the female rats.