Time course of the corticosteroid-dopaminergic interaction during metyrapone and dexamethasone administration

Recent studies performed with depressed patients and normal subjects suggest that corticosteroids may alter dopaminergic activity. We measured the time course of the interaction between corticosteroid and plasma homovanillic acid (HVA) levels in 10 young healthy subjects after the administration of 2 mg of dexamethasone in session 1 and after the administration of 4.5 g of metyrapone in session 2. Plasma levels of adrenocorticotropic hormone (ACTH), 11-desoxycortisol, cortisol, HVA, and 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. Dexamethasone administration resulted in a significant decrease in plasma levels of ACTH, 11-desoxycortisol, and cortisol at all time points and to a significant decrease in PRL secretion in the early morning. Plasma HVA levels were unchanged after dexamethasone administration. Metyrapone administration resulted in a significant decrease in cortisol levels and a significant increase in ACTH and 11-desoxycortisol levels. Plasma HVA levels were significantly increased in the early morning, while PRL levels were unaltered. These results are discussed in relation to the neurochemical and behavioral changes associated with steroid administration and interpreted with regard to a possible association between HVA and PRL in the effects of corticosteroids on dopaminergic activity.