RESUMO
Adrenaline [A] and noradrenaline [NA] are the hormones secretated during stress. Synthesis of the neurotransmitter 5 - hydroxytryptamine [5 - HT, Serotonin] in brain is increased during stress. Present paper concerns the effect of adrenaline and noradrenaline on brain serotonin metabolism so that the effect of stress hormones on brain 5 - HT metabolism can be evaluated in the absence of other non specific effect of stress. Adrenaline and noradrenaline given in doses of 1. 0, 2. 0 and 3. 0 mg/kg [i. p.] inhibited liver tryptophan pyrrolase activity in apo tryptophan pyrrolase lacking species, rabbit in one hour. Serum level of total tryptophan decreased but those of free tryptophan increased. Brain level of tryptophan and serotonin were also increased. The results suggest, that the increase of serum free tryptophan may have a role in the enhancement of 5 - HT metabolism observed in adrenaline and noradrenaline injected rabbits