Among psychiatric disorders, depression and generalized anxiety are probably the most
common stress-related illnesses. These diseases are underlain, at least partly, by
dysfunctions of neurotransmitters and neurohormones, especially within the serotoninergic
(5-HT) system and the hypothalamo-pituitary-adrenal (HPA) axis, which are also the
targets of drugs used for their treatment. This review focuses on the nature of the
interactions between central 5-HT and corticotrope systems in animal models, in particular
those allowing the assessment of serotoninergic function following experimental manipulation
of the HPA axis. The review provides an overview of the HPA axis and the 5-HT system
organization, focusing on the 5-HT(1A) receptors, which play a pivotal role in the
5-HT system regulation and its response to stress. Both molecular and functional aspects
of 5-HT/HPA interactions are then analyzed in the frame of psychoaffective disorders.
The review finally examines the hippocampal neurogenesis response to experimental
paradigms of stress and antidepressant treatment, in which neurotrophic factors are
considered to play key roles according to the current views on the pathophysiology
of depressive disorders.