Aim: 

It is noteworthy that pharmacological manipulation of the serotonin tone is able to alter the effects elicited by psycho-stimulants in animal models. Here, we investigated whether L-tryptophan (TRP)-deficient diet, which is known to decrease central serotonergic tone, may affect response to amphetamine (AMPH).

Methods: 

Rats were fed with TRP-deficient diet for two weeks, and the effect on basal and AMPH-induced motor activity and impairment of prepulse inhibition of the startle (PPI) was investigated. Moreover, an additional group of control and TRP-deficient rats was used to measured basal and AMPH-induced dopamine release in striatum and nucleus accumbens.

Results: 

TRP-deficient diet failed to significantly affect spontaneous motor activity and PPI response. However, the diet was able to increase the effect of AMPH. Indeed, TRP-deficient diets enhanced AMPH-induced PPI impairment and increased motor activity, which were paralleled by increased AMPH-induced dopamine release in striatum and nucleus accumbens.

Conclusion: 

These results show that manipulation of the central serotonin tone by means of a TRP-deficient is able to alter the response to psycho-stimulants, such as amphetamine, in rats.