AVP and major depressive disorder: Findings in depressed patients of increased CRH levels in the CSF [17] and elevated numbers of CRH [18] and arginine-vasopressin (AVP) [19] expressing neurons in the paraventricular nucleus of the hypothalamus as well as the observation of reduced CRH binding sites in the frontal cortex of suicide victims [20] gave reason to the assumption that depression is characterized by a hypothalamic overdrive of CRH and/or AVP which in consequence leads to receptor down-regulation in the corticotrophs of the pituitary gland.