The role of melatonin in the pathogenesis and therapy of depressive disorders (literature review)

Background. Depression is one of the most common diseases worldwide. Despite the ongoing flow of research on affective disorders and the emergence of new antidepressants, depression remains a serious problem. Among the hypotheses of the occurrence of depressive disorders hypothesis associated with dysfunction of neurotransmitters and chronobiology concept (altered circadian rhythms that are implemented with the help of melatonin) occupy a leading place. The latter formed the basis of the melatonin theory of depression, the founder of which was A. Lewy. Objective – of this work was to review the literary sources that highlights the role of melatonin in the pathogenesis and therapy of depressive disorders. Materials and methods. Was analyzed publications from databases of Pubmed, Web of Science, Google Scholar with keywords – depression, melatonin, biorhythmology, agomelatine, desynchronosis. Results. According to the chronobiological concept of depression, the only cause of depressive disorders is the phase inconsistency of different circadian rhythms among themselves due to weakness in the work of their governing structures. In particular disorders of the central monoaminergic transmission is capable first and foremost negatively affect the role of lead retooling apparatus – suprachiasmatic nuclei of the hypothalamus, which leads to an acceleration of «progress» biological clocks and the formation of internal desynchronosis. Benefit chronobiological nature of the depressions suggest 3 basic facts: pronounced cyclicity in the clinical picture of the majority of depressive disorders and the availability of insomnia; the possibility of effective influence on the course of depression chronobiological methods (sleep deprivation, light therapy, therapy with «darkness»); the existence of many classes of antidepressants activity relative to circadian rhythms. A review of literature sources has shown that disorders of melatonin secretion is a characteristic feature of patients with depressive disorders. But the focus of this disturbance may be different: both downward and upward. This fact is due to the presence of biochemically different subgroups of depression. Antidepressant effect of melatonin today is quite controversial. The effect of another melatoninergic antidepressant, agomelatine, may be due to both the effect on melatonin receptors and antagonistic properties against serotonin 5-HT2C receptors. Conclusions. Each clinical case of depression is unique and requires careful evaluation to determine the quality of the therapeutic response to antidepressants. In this regard, there is a question of developing a differentiated approach to the treatment of various depressive disorders, in particular – a preliminary laboratory assessment of pineal function.