The prolonged effects of tetrapeptide-amide on dopamine and serotonin metabolism in brain structures

A single injection of tetrapeptide-amide d-Tyr-Ala-Gly-Phe-NH2 (500 mkg/kg, i/p) to rats or rabbits caused an increase of MAO A activity, but a decrease of MAO B activity, especially in nucleus caudatum in comparison with brain cortex. The changes of MAO A and B activities, of tryptophan- and tyrosine hydroxylases activities, and the changes of serotonin concentration were found within 30 min as well as 3 days after a single injection of tetrapeptide-amide.