Avances en el estudio de la neurobiología de la depresión

Introduction: major depression disorder (MDD) is a common psychiatric condition, it has high morbility rates and is closely related to suicide. Objective: to provide an update in the study of the neurobiology of depression, focusing on the potential role of the melanin-concentrating hormone (MCH) in this condition. Method: a bibliographical review with an emphasis on our own original studies. Results: the melanin-concentrating hormone is a peptide neuromodulator syhthetized by neurones in the hypothalamus. MCHergic neurons send projection towards different areas in the central nervous system, including areas associated to the regulation of the sleep-wake cycle, as well as different structures in the limbic system that take part in the regulation of mood. In spite of several studies having proved the MCHergic system with the control of energetic homeostasis, recent findings have enabled to identify a role for this system in the sleep generator mechanisms. Similarly, data arising from several studies suggests that MCH would be involved in the major depression disorder. Our own preclinical studies tend to pint out the MCH promotes the generation of REM sleep and a type of depression. Apparently both effects would be mediated through the modulation of the activity on the serotoninergic neurons in the dorsal raphe nucleus. Conclusions: paraclinical studies suggest the leading role of the MCHergic system in the pathophysiology of depression. It is to be proved still, whether this affirmation is true for patients with major depression disorder.