Biochemistry of depressive disorders. role of serotonin, amino acid neurotransmitters, substance p and neurosteroids

The present paper reviews biochemical aspects of depression, focusing on abnormalities in: 1) serotonergic neurotransmission; 2) GABA and glutamate systems; 3) substance P; 4) neurosteroids. The results of literature search are discussed as regards their implications for the discovery of novel, more effective antidepressant treatments. Indeed, although depression is traditionally regarded as a treatable mental disorder, up to 50% of such patients may not have a satisfactory remission of symptoms after an adequate antidepressant treatment.