TIME-COURSE OF THE CORTICOSTEROID-DOPAMINERGIC INTERACTION DURING METYRAPONE AND DEXAMETHASONE ADMINISTRATION

Recent studies performed with depressed patients and normal subjects s uggest that corticosteroids may alter dopaminergic activity, We measur ed the time course of the interaction between corticosteroid and plasm a homovanillic acid (HVA) levels in 10 young healthy subjects after th e administration of 2 mg of dexamethasone in session 1 and after the a dministration of 4.5 g of metyrapone in session 2. Plasma levels of ad renocorticotropic hormone (ACTH), 11-desoxycortisol, cortisol, HVA, an d prolactin (PRL) were measured at 08:00, 09:00, 12:00, 15:00, and 16: 00 h on a baseline day and during both drug-administration sessions, D examethasone administration resulted in a significant decrease in plas ma levels of ACTH, 11-desoxycortisol, and cortisol at all time points and to a significant decrease in PRL secretion in the early morning. P lasma HVA levels were unchanged after dexamethasone administration. Me tyrapone administration resulted in a significant decrease in cortisol levels and a significant increase in ACTH and 11-desoxycortisol level s. Plasma HVA levels were significantly increased in the early morning , while PRL levels were unaltered, These results are discussed in rela tion to the neurochemical and behavioral changes associated with stero id administration and interpreted with regard to a possible associatio n between HVA and PRL in the effects of corticosteroids on dopaminergi c activity.