Effects of amino acid precursors on catecholamine synthesis in the brain

Abstract

• 1.

  1. We studied L-DOPA, DOPS and tyrosine as precursors of CAs using GC/CI/MS techniques to measure the effects of these amino acids in rats on the production of metabolites in brain and urine.

• 2.

  2. L-DOPA caused a significant increase in levels of brain NE metabolites which was not blocked by the peripheral decarboxylase inhibitor, Ro4-4602.

• 3.

  3. DOPS increased brain levels of both NE and DA metabolites but the increases in NE (but not DA) metabolites were blocked by Ro4-4602.

• 4.

  4. Tyrosine had no significant effect on CA metabolites in brain, but metabolites of tyramine and octopamine were increased 2- to 3-fold.

• 5.

  5. We conclude that interpretation of results obtained with these precursor amino acids may be complicated by their lack of specificity or by conversion to amines in the brain capillaries.