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Neuropharmacology. 2018 Mar 1;130:62-70. doi: 10.1016/j.neuropharm.2017.11.040. Epub 2017 Dec 2.

Melanin-Concentrating Hormone acts through hypothalamic kappa opioid system and p70S6K to stimulate acute food intake.

Author information

1
Instituto de Salud Carlos III, CIBER Fisiopatologia de la Obesidad y Nutrición (CIBERobn), Spain; Department of Physiology, CIMUS - University of Santiago de Compostela, Santiago de Compostela 15782 Spain. Electronic address: amparo.romero@usc.es.
2
Department of Physiology, CIMUS - University of Santiago de Compostela, Santiago de Compostela 15782 Spain.
3
Development and Plasticity of the Neuroendocrine Brain, Jean-Pierre Aubert Research Center, INSERM, U1172, University of Lille, France.
4
Instituto de Investigaciones Sanitarias (IDIS), University of Santiago de Compostela, Spain.
5
KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Norway.
6
MRC Metabolic Disease Unit, Institute of Metabolic Science, University of Cambridge, UK.
7
Department of Experimental and Health Science, Universitat Pompeu Fabra, Barcelona Spain.
8
Department of Neuroscience and Pharmacology, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, The Netherlands.
9
Instituto de Salud Carlos III, CIBER Fisiopatologia de la Obesidad y Nutrición (CIBERobn), Spain; Department of Physiology, CIMUS - University of Santiago de Compostela, Santiago de Compostela 15782 Spain; Instituto de Investigaciones Sanitarias (IDIS), University of Santiago de Compostela, Spain.
10
Instituto de Salud Carlos III, CIBER Fisiopatologia de la Obesidad y Nutrición (CIBERobn), Spain; Department of Physiology, CIMUS - University of Santiago de Compostela, Santiago de Compostela 15782 Spain; Instituto de Investigaciones Sanitarias (IDIS), University of Santiago de Compostela, Spain. Electronic address: ruben.nogueiras@usc.es.

Abstract

Melanin-Concentrating Hormone (MCH) is one of the most relevant orexigenic factors specifically located in the lateral hypothalamic area (LHA), with its physiological relevance demonstrated in studies using several genetically manipulated mice models. However, the central mechanisms controlling MCH-induced hyperphagia remain largely uncharacterized. Here, we show that central injection of MCH in mice deficient for kappa opoid receptor (k-OR) failed to stimulate feeding. To determine the hypothalamic area responsible for this MCH/k-OR interaction, we performed virogenetic studies and found that downregulation of k-OR by adeno-associated viruses (shOprk1-AAV) in LHA, but not in other hypothalamic nuclei, was sufficient to block MCH-induced food intake. Next, we sought to investigate the molecular signaling pathway within the LHA that mediates acute central MCH stimulation of food intake. We found that MCH activates k-OR and that increased levels of phosphorylated extracellular signal regulated kinase (ERK) are associated with downregulation of phospho-S6 Ribosomal Protein. This effect was prevented when a pharmacological inhibitor of k-OR was co-administered with MCH. Finally, the specific activation of the direct upstream regulator of S6 (p70S6K) in the LHA attenuated MCH-stimulated food consumption. Our results reveal that lateral hypothalamic k-OR system modulates the orexigenic action of MCH via the p70S6K/S6 pathway.

KEYWORDS:

Food intake; Hypothalamus; Kappa-opioid receptor; Melanin-Concentrating Hormone; Melanin-Concentrating Hormone (MCH) (PubChem CID: 24868207); Naloxone hydrochloride (PubChem CID: 5464092); Norbinaltorphimine dyhydrochloride (norBNI) (PubChem CID: 5480230)

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