238 | Behavioral effects induced by intranasal administration of melanin-concentrating hormone in rats: relevance of its role in mood disorders

Neurochemistry and Neuropharmacology

Author: Maria Valentina Perini Buenahora | Email: valeperini95@gmail.com

Valentina Perini , Florencia Bai , Cecilia Scorza , Jessika Urbanavicius

1° Departamento de Neurofarmacología Experimental, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay

The hypothalamic neuropeptide melanin-concentrating hormone (MCH) has been involved in the regulation of mood disorders, like depression, a high prevalent psychiatric disorder worldwide; however, its role remains under study. We demonstrated an interaction between MCHergic and monoaminergic systems, since MCH acute and locally administered into the dorsal and median raphe, and the Locus Coeruleus, induced a prodepressive response in the rat forced swim test. An anhedonic response was also demonstrated after its acute and intranasal (i.n.) systemic administration in the sucrose preference test. Given the well-known comorbidity between depression and anxiety disorders, we hypothesized that the MCH-induced anhedonic response is accompanied by an anxiogenic response and an increase in corticosterone levels (a stress hormone resulting after the activation of the hypothalamus-pituitary-adrenal axis). To explore this hypothesis, we evaluated the anxiety-related behaviors following i.n. administration of MCH (15 µg/30 µL) in male adult rats using the open field (OF) and elevated plus maze (EPM) tests. Our results showed that MCH did not induce significant changes in anxiety-related responses, neither in the OF nor in the EPM test, at 30 or 60 min after administration. Ongoing experiments are being carried out to measure the plasmatic corticosterone levels, to elucidate its role in anxiety. Our findings collaborate to the understanding of the role of MCHergic system in mood disorders.