AMPHETAMINE AND VIGABATRIN DOWN-REGULATE AROMATIC L-AMINO-ACID DECARBOXYLASE MESSENGER-RNA LEVELS

Aromatic L-amino acid decarboxylase (AADC) has previously been shown t o be up-regulated at the level of its protein activity and its mRNA ab undance by antipsychotic drugs. Its activity has also been shown to be down-regulated by dopamine agonists including amphetamine. In this st udy we have injected rats for up to 32 days with amphetamine and the a nti-epileptic drug vigabatrin, both of which can cause psychosis with similarities to schizophrenia. We have shown that AADC mRNA levels are reduced in most brain regions by both drugs. Cocaine and other non-ps ychotogenic anti-epileptic drugs had no effect in this paradigm. Two p roducts of this enzyme are implicated in psychotogenesis.