Adrenocorticotropin and cortisol response to lysine vasopressin in relation to the outcome of the dexamethasone suppression test in major depressive disorder

The pathophysiology behind the abnormalities of the hypothalamic pituitary adrenal cortex axis found in patients with major depressive disorder was studied by the use of the vasopressin test. The response of plasma adrenocorticotropin (ACTH) and cortisol to the injection of 10 IU lysine-vasopressin (LVP) was investigated in 18 patients meeting the DSM-III criteria for major depressive episode. The response was correlated to the outcome of the dexamethasone suppression test (DST) with the use of two different cut-off points, 139 nmol/l and 200 nmol/l respectively. The results show that no significant difference was found in ACTH or cortisol response between patients having a normal or abnormal DST. The results do not seem to support the hypothesis that the abnormalities of the hypothalamic pituitary adrenal cortex axis involve a hypersecretion of corticotropin-releasing factor (CRF) and a subsequent desensitization of the corticotrophs to CRF-stimulated ACTH release.