[Pathophysiology of depression].

Neurobiological findings of depression are reviewed in this paper. Modern neurobiological methods have revealed pathophysiological mechanism associated with depression. Monoamine hypothesis, which was advocated in the 1950's, emphasizes that the deficiency of monoamine neurotransmitters bring about depressive symptoms. This theory played an important role in promoting the development of new antidepressants, but some inconsistent findings were pointed out concerning this theory. Neuroendocrine studies have revealed the hypothalamic-pituitary-adrenal (HPA) axis dysfunctions in depressive patients, and increased activity of HPA axis are considered as state marker of depression. Morphological changes of hippocampus, polymorphism of serotonin transporter gene, and down regulation of neurotrophin are also discussed in this review.