THE EFFECTS OF L-DIHYDROXYPHENYLALANINE ON ALERTNESS AND MOOD IN ALPHA-METHYL-PARA-TYROSINE-TREATED HEALTHY HUMANS - FURTHER EVIDENCE FOR THE ROLE OF CATECHOLAMINES IN AROUSAL AND ANXIETY

Treatment with alpha-methyl-para-tyrosine (AMPT), a catecholamine synt hesis inhibitor, has been shown to produce pronounced increases in sle epiness and mild increases in negative mood and anxiety when administe red to healthy male adults. The present study was conducted to ascerta in whether these effects of AMPT ave secondary to decreases in brain c atecholamines or whether they represent nonspecific drug effects. Fort y-one healthy males were randomized to one of four treatment groups. ( 2) Treatment with AMPT alone (AMPT/placebo); (2) treatment with AMPT p lus L-dopa/carbidopa carbidopa (AMPT plus L-dopa/carbidopa); (3) treat ment with L-dopa/carbidopa alone (placebo plus L-dopa/carbidopa); or ( 4) treatment with placebo alone (placebo plus placebo). Repeated measu res of alertness, mood, and anxiety were obtained over a three-day per iod of drug treatment and following drug discontinuation. As before, A MPT treatment led to increased sleepiness. In addition, AMPT treatment led to decreased calmness, increased tension and anger, and a trend f or increased depression. Replacement of catecholamine stoves with L-do pa reversed the effects of AMPT and was associated with a more rapid r ecovery from AMPT's effects. These findings indicate that AMPT's effec ts on alertness and anxiety are catecholamine-specific. Further, they provide additional evidence that catecholamines are involved in the re gulation of normal states of arousal, and they are consistent with the view that brain catecholaminergic dysregulation is involved in pathol ogical anxiety states.