The effects of L-dihydroxyphenylalanine on alertness and mood in α-methyl-para-tyrosine-treated healthy humans. Further evidence for the role of catecholamines in arousal and anxiety

Una D McCann, David Thorne, Martica Hall, Kathy Popp, Warren Avery, Helen Sing, Maria Thomas, Gregory Belenky

Research output: Contribution to journalArticle


Treatment with α-methyl-para-tyrosine (AMPT), a catecholamine synthesis inhibitor, has been shown to produce pronounced increases in sleepiness and mild increases in negative mood and anxiety when administered to healthy male adults. The present study was conducted to ascertain whether these effects of AMPT are secondary to decreases in brain catecholamines or whether they represent nonspecific drug effects. Forty-one healthy males were randomized to one of four treatment groups. (1) Treatment with AMPT alone (AMPT/placebo); (2) treatment with AMPT plus L-dopa/ carbidopa (AMPT plus L-dopa/carbidopa); (3) treatment with L-dopa/carbidopa alone (placebo plus L-dopa/ carbidopa); or (4) treatment with placebo alone (placebo plus placebo). Repeated measures of alertness, mood, and anxiety were obtained over a three-day period of drug treatment and following drug discontinuation. As before, AMPT treatment led to increased sleepiness. In addition, AMPT treatment led to decreased calmness, increased tension and anger, and a trend for increased depression. Replacement of catecholamine stores with L-dopa reversed the effects of AMPT and was associated with a more rapid recovery from AMPT's ejfects. These findings indicate that AMPT's effects on alertness and anxiety are catecholamine-specific. Further, they provide additional evidence that catecholamines are involved in the regulation of normal states of arousal, and they are consistent with the view that brain catecholaminergic dysregulation is involved in pathological anxiety states.

Original languageEnglish (US)
Pages (from-to)41-52
Number of pages12
Issue number1
Publication statusPublished - 1995
Externally publishedYes



  • AMPT
  • Anxiety
  • Arousal
  • Carbidopa
  • Catecholamines
  • L-dopa
  • Mood

ASJC Scopus subject areas

  • Psychiatry and Mental health
  • Pharmacology

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