ABSTRACT
This chapter discusses the 5-HTergic system, clearly the study of one neurotransmitter system in isolation cannot entirely explain the pathogenesis of such a complex disease. The classical “monoamine hypothesis” of depression suggests that this disorder is caused by decreased availability and diminished function of the MAergic system, and thus antidepressant treatments exert therapeutic action by increasing synaptic MA availability and neurotransmission. Initially, disturbances in serotonergic function were implicated in depressive disorder, primarily with endogenous or melancholic features. Biological research in psychiatry has a strong nosological orientation. It would appear, however, that use of the functional or dimensional approach, complementary to the nosological approach, could increase our understanding of biological variables in psychiatric disorders. The classical monoamine hypothesis of depression initially proposed that decreased availability of NE and hypofunction of the NEergic system are causally related to depressive illness. From the foregoing data, it certainly appears that 5-HT dysfunction is involved in depression.
