New approaches to antidepressant drug design: cytokine-regulated pathways

Monoamine oxidase inhibitor and tricyclic antidepressants have been serendipitously used for the treatment of depression for more than half a century and subsequently found to promote monoaminergic signals in the brain. Antidepressant drugs are still clinically used and industrially designed on the basis of the monoaminergic theory. Recent developments regarding selective monoaminergic uptake inhibitors can further improve the safe and rational treatment for patients with depression. However, monoamine-based antidepressants may cause unfavorable and incomplete remission of a considerable number of patients with depression; therefore, development of new antidepressant drugs based on other mechanisms is required. Meanwhile, there has been an impressive accumulation of knowledge about cytokines that might contribute to the understanding of the pathophysiology of depression. Therefore, this review focuses on the association between depressive disorder and cytokines and discusses the strategies for developing new cytokine-based antidepressant drugs.