Melanin-concentrating hormone (MCH) in the median raphe nucleus: fibers, receptors and cellular effects

Publication date: Available online 3 January 2020Source: PeptidesAuthor(s): Claudia Pascovich, Patricia Lagos, Jessika Urbanavicius, Andrea Devera, Mayda Rivas, Alicia Costa, Ximena López Hill, Atilio Falconi, Cecilia Scorza, Pablo TorteroloAbstractSerotonergic neurons of the median raphe nucleus (MnR) and hypothalamic melanin-concentrating hormone (MCH)-containing neurons, have been involved in the control of REM sleep and mood.In the present study, we examined in rats and cats the anatomical relationship between MCH-containing fibers and MnR neurons, as well as the presence of MCHergic receptors in these neurons. In addition, by means of in vivo unit recording in urethane anesthetized rats, we determined the effects of MCH in MnR neuronal firing.Our results showed that MCH-containing fibers were present in the central and paracentral regions of the MnR. MCHergic fibers were in close apposition to serotonergic and non-serotonergic neurons. By means of an indirect approach, we also analyzed the presence of MCHergic receptors within the MnR. Accordingly, we microinjected MCH conjugated with the fluorophore rhodamine (R-MCH) into the lateral ventricle. R-MCH was internalized into serotonergic and non-serotonergic MnR neurons; some of these neurons were GABAergic. Furthermore, we determined that intracerebroventricular administration of MCH induced a significant decrease in the firing rate of 53% of MnR neurons, while the juxtacellular administration of MCH reduced the frequenc...

Source: Peptides - January 5, 2020 Category: Biochemistry Source Type: research