Changes in the Hypothalamic-Pituitary-Adrenal Axis and Leptin Levels during Antidepressant Treatment

BACKGROUND: In depressed patients, overstimulation of the hypothalamo-pituitary-adrenocortical (HPA) system, probably caused by glucocorticoid receptor resistance, is the most consistent neurobiological finding. Glucocorticoids themselves are reported to increase leptin synthesis and secretion in humans. METHODS: We examined alterations in plasma levels of leptin as well as changes in the HPA system function using the combined dexamethasone/corticotropin-releasing hormone (dex/CRH) test on admission and at discharge in 74 depressed inpatients. RESULTS: Mean leptin concentration did not change significantly between admission and discharge. However, changes in ACTH response and partial cortisol response to the combined dex/CRH test between admission and discharge were significantly correlated with leptin levels at discharge. CONCLUSIONS: Leptin levels at discharge rise as the HPA axis normalizes. These findings may be explained by an improvement in glucocorticoid receptor sensitivity among depressed patients during antidepressant therapy and a consecutively increased influence of glucocorticoids on leptin levels via the glucocorticoid receptor.