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

Release of corticotropin after administration of corticotropin-releasing hormone in depressed patients in relation to the dexamethasone suppression test

The possible hypersecretion involvement of corticotropin-releasing hormone (CRH) in the pathophysiology of hypothalamic-pituitary-adrenocortical axis disturbances in patients with major depressive episode and with an abnormal dexamethasone suppression test (DST) was investigated. The corticotropin (ACTH) and cortisol response to the injection of 45 micrograms of synthetic human CRH at 1630 were analyzed in 24 inpatients with normal (suppressors) or abnormal (nonsuppressors) DST. The outcome of the DST was analyzed using 3 cut-off points for the cortisol levels. The clinical assessments included two rating scales. The results showed that nonsuppressors had a significantly lower ACTH response to CRH stimulation than suppressors at all cut-off points (calculated as net area under the curve and as the difference between the peak and the baseline level) despite no significant differences in the severity of depression.

Stimulation of the pituitary-adrenal axis with a low dose [Arg8]-vasopressin in depressed patients and healthy subjects

Graded doses arginine-vasopressin (AVP) were administered to depressed patients and control subjects to compare the sensitivity of the pituitary-adrenal system of these subjects for this compound. The plasma levels of cortisol, adrenocorticotropic hormone (ACTH) and beta-endorphin were measured before and after intravenous AVP injection. The hormonal output was taken as a measure of pituitary-adrenal function. In control subjects 3 doses AVP and placebo were used, whereas in patients two doses AVP, a low and a high dose, and placebo were tested. All tests were carried out in the afternoon when the pituitary-adrenal system is stable and more susceptible for stimulation. Patients were subdivided into dexamethasone suppressors and nonsuppressors based on their DST status before testing to look for differences among these groups. Control subjects showed no response of the hormones to the lowest dose AVP and a moderate response to the higher doses. Interestingly, depressed patients as compared to controls responded more to the lowest dose AVP in particular with respect to ACTH. DST status did not influence the results. These findings suggest an enhanced sensitivity of the pituitary to low doses AVP in depressed patients. Thus, AVP might play a role in HPA dysfunction in depression.