EVIDENCE FOR CYCLIC AMP-MEDIATED INCREASE OF AROMATIC L-AMINO-ACID DECARBOXYLASE ACTIVITY IN THE STRIATUM AND MIDBRAIN

AromatiC L-amino acid decarboxylase (AAAD) activity of mouse striatum and midbrain increased after an intracerebroventricular injection of either forskolin or 8-bromo-cyclic AMP. The increase was transient, peaking between 15 and 30 min and returning to baseline by approximately 90 min. The increase of AAAD activity after forskolin was not affected by pretreatment with cycloheximide. Kinetic studies indicated an apparent increase of V(max) with little change of the K(m) for L-DOPA or pyridoxal 5'-phosphate. We conclude that AAAD activity of striatum and midbrain can be modulated by a cyclic AMP-dependent process.