Hypothalamic-pituitary-adrenal axis effects on plasma homovanillic acid inman

Background: Effects of the hypothalamic-pituitary-adrenal (HPA) axis on cen tral dopaminergic systems have been proposed to underlie the development of psychotic symptoms in depression, This study examined HPA axis hormone eff ects on plasma levels of homovanillic acid (HVA), the dopamine metabolite, in healthy volunteers, using a placebo-controlled double-blind, random-assi gnment, crossover design, On the basis of preliminary studies, we hypothesi zed that HPA axis hormones would produce delayed effects on plasma HVA leve ls measured in the afternoon; Methods: Ten healthy subjects underwent a standard protocol an four occasio ns and each time received ovine corticotropin-releasing hormone, synthetic adrenocorticotropic hormone (ACTH), cortisol, or placebo. Plasma HVA was me asured at 9 AM and 4 PM an Day 1, immediately prior to administration of th e test substance at 7 PM, then at 30-60-min intervals until 11 PM. Plasma H VA levels were subsequently obtained at 9 AM and 4 PM on Days 2 and 3. Results: As predicted, there were significant differences between test subs tances in delayed effects on afternoon HVA levels measured on Days 2 and 3, with cortisol and ACTH producing greater increases in HVA than placebo. Ac ute effects of HPA axis hormones on HVA were not found, while differences b etween test substances in delayed effects on morning HVA levels approached significance, Conclusions:HPA axis hormones exert delayed effects an plasma HVA levels in healthy humans. (C) 1999 Society of Biological Psychiatry.