Effect on rats and mice of a diet with low tryptophan content (maize flour)

Female Wistar rats when crowded together become aggressive if fed a diet with low tryptophan (Trp) content (maize, flour, Mf). When isolated during 30 days and fed Mf they show a decrease of weight, of total plasma Trp, and of Trp and 5-hydroxytryptamine (5-HT) in brain stem, but 5-hydroxyindolacetic acid (5-HIAA) of the same cerebral area does not change. These results partially agree with other authors observations. Mice isolated during 47 days and fed with Mf do not show any significant weight variation, the hypermotility of isolated mice on normal diet persists, but 5-HT and 5-HIAA significantly decreases in total brain, an effect that has been observed by another author. The effect on 5-HIAA does not depend on the diet, either balanced or with low Trp content.