Tryptophan ingestion by pregnant rats induces pituitary and mammary tumours in the adult female offspring

The present study was designed to evaluate the longterm consequences of try ptophan treatment on the central serotonergic activity in the female offspr ing of rats, and particularly on serotonin-controlled hormone release. Duri ng the second half of gestation, tryptophan (200 mg/kg/day) was given daily by stomach intubation to pregnant rats and the brain concentrations of ser otonin and 5-hydroxyindole acetic acid and the plasma concentrations of pro lactin, progesterone, oestradiol and luteinizing hormone were quantified in the adult female offspring. The offspring showed an increase in hypothalam ic serotonin and serum progesterone and prolactin, In addition, maternal in gestion of tryptophan induced a marked rise in 665-day-old offspring in the incidence of both pituitary prolactinomas (62%) and mammary adenomas (49%) , Present data suggest that tryptophan regulates serotonergic differentiati on during early development. A transitory modification of the tryptophan co ncentration in the fetal brain induces a permanent increase in hypothalamic serotonin level and, in addition to modifying the release of prolactin, in creases the incidence of tumours in the hypophysis and mammary gland.