<p>This compound binds to the melatoninergic receptors and the serotoninergic 5-HT2c receptor giving rise to the Melatonin Agonist and Selective Serotonin Antagonist (MASSA) concept. The melatoninergic receptors MT1 and MT2, are G protein coupled receptors and they act through decreasing cAMP and cGMP. Agomelatine strongly binds to and stimulates the activity of MT1 and MT2 receptors normalizing the disturbed circadian rhythms and disrupted sleep-wake cycles. Unlike the existing antidepressants, agomelatine does not inhibit the uptake of serotonin, norepinephrine or dopamine. It inhibits 5HT-2C receptor (G protein coupled receptor which increases IP3/DAG secondary messenger system) found abundantly in the SCN, frontal cortex, hippocampus and basal ganglia involved in the mood, motor and cognitive deficits associated with depressive states. 5HT-2C receptor antagonism increases norepinephrine and dopamine levels in the frontal cortex of the brain. This action of agomelatine produces antidepressant, antianxiety and also increases slow-wave sleep which is decreased in depression. It has been observed that it can increase neurogenesis in the hippocampus and may also have neuroprotective effects (by influencing glutamate release, glucocorticoid receptor gene expression and various neurotropic factors) which might also contribute to its antidepressant effects. A study has shown that agomelatine alleviates sleep disturbances after one week of therapy and by two weeks antidepressant effects manifest. The combined actions of agomelatine at MT1, MT2, and 5HT-2C receptors can improve the disturbed circadian rhythm and abnormal sleep pattern thus produce the antidepressant effect. These unique effects suggest that it might be effective for the treatment of seasonal affective disorder like anxiety and bipolar depression.</p>