The effect of alpha-melanocyte stimulating hormone (alpha-msh) on the metabolism of biogenic amines in the rat brain.

The effect of the chronic administration of alpha-MSH on the incorporation of tritiated tyrosine into noradrenalin and dopamine and of tritiated tryptophan into serotonin was studied in different regions of the rat brain. Alpha-MSH increased the incorporation of tritiated trytophan into serotonin in the cortex and slightly decreased that of tryosine into the dopamine in the hypothalamus. As the brain concentration of serotonin was unchanged in the animals treated with alpha-MSH, it is suggested that some of the changes in behavior, which other investigators have found following the administration of peptides containing the same sequence of amino acids to that found in MSH, could be associated with an increased turnover of cortical serotonin.