INCREASED RESPONSIVENESS TO 5-METHOXY-N,N-DIMETHYLTRYPTAMINE IN MICE ON A HIGH TRYPTOPHAN DIET

5-Methoxy-N,N-dimethyltryptamine (5 mg/kg i.v.) given to mice produced head twitch behaviour. Mice maintained on a high (1.2%) tryptophan diet for 18 days had a significantly increased response to 5-methoxy-N,N-dimethyltryptamine compared to mice on a normal (0.2%) tryptophan diet. The response was still significantly increased 4 days after removing the high tryptophan diet. There was no significant difference in response between mice on the two diets after 3 days. Brain tryptophan, 5-hydroxytryptamine and 5-hydroxy-indoleacetic acid were significantly increased in mice on the high tryptophan diet for 3 and 18 days, but the increases on day 18 were much less than on day 3. The results are discussed in relation to the role of 5-hydroxytryptamine turnover in the control of 5-hydroxy-tryptamine receptor sensitivity. © 1979.