Chronic loss of melanin-concentrating hormone affects motivational aspects of feeding in the rat

• Published in: PloS one Vol. 6; no. 5; p. e19600
• Main Authors: Mul, Joram D, la Fleur, Susanne E, Toonen, Pim W, Afrasiab-Middelman, Anthonieke, Binnekade, Rob, Schetters, Dustin, Verheij, Michel M M, Sears, Robert M, Homberg, Judith R, Schoffelmeer, Anton N M, Adan, Roger A H, DiLeone, Ralph J, De Vries, Taco J, Cuppen, Edwin
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 05.05.2011; Public Library of Science (PLoS)
• Subjects: Animal behavior; Animals; Biology; Body weight; Body Weight - drug effects; Brain; Brain research; Cognition & reasoning; Conditioning, Operant - drug effects; Consummatory behavior; Dietary Fats - administration & dosage; Dietary Fats - pharmacology; Dopamine; Dopamine - metabolism; Dopamine transporter; Energy balance; Epidemics; Feeding; Feeding behavior; Feeding Behavior - drug effects; Feeding Behavior - physiology; Food; Food consumption; Food intake; Hormones; Hyperphagia - physiopathology; Hypothalamic Hormones - administration & dosage; Hypothalamic Hormones - deficiency; Hypothalamic Hormones - metabolism; Hypothalamic Hormones - pharmacology; Hypothalamus; Hypothalamus (lateral); Infusion; Injections, Intraventricular; Medicine; Melanin; Melanin-concentrating hormone; Melanins - administration & dosage; Melanins - pharmacology; Motivation - drug effects; Motivation - physiology; Neostriatum - drug effects; Neostriatum - metabolism; Neural circuitry; Neural networks; Neuropeptides; Neurosciences; Nucleus accumbens; Nucleus Accumbens - drug effects; Nucleus Accumbens - metabolism; Obesity; Oligopeptides - administration & dosage; Oligopeptides - pharmacology; Operant conditioning; Pituitary Hormones - administration & dosage; Pituitary Hormones - pharmacology; Protein Precursors - deficiency; Protein Precursors - metabolism; Rats; Reinforcement (Psychology); Rodents; Signaling; Transporter; New York; Netherlands; United States > US; Connecticut
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0019600

Current epidemic obesity levels apply great medical and financial pressure to the strenuous economy of obesity-prone cultures, and neuropeptides involved in body weight regulation are regarded as attractive targets for a possible treatment of obesity in humans. The lateral hypothalamus and the nucleus accumbens shell (AcbSh) form a hypothalamic-limbic neuropeptide feeding circuit mediated by Melanin-Concentrating Hormone (MCH). MCH promotes feeding behavior via MCH receptor-1 (MCH1R) in the AcbSh, although this relationship has not been fully characterized. Given the AcbSh mediates reinforcing properties of food, we hypothesized that MCH modulates motivational aspects of feeding.Here we show that chronic loss of the rat MCH-precursor Pmch decreased food intake predominantly via a reduction in meal size during rat development and reduced high-fat food-reinforced operant responding in adult rats. Moreover, acute AcbSh administration of Neuropeptide-GE and Neuropeptide-EI (NEI), both additional neuropeptides derived from Pmch, or chronic intracerebroventricular infusion of NEI, did not affect feeding behavior in adult pmch(+/+) or pmch(-/-) rats. However, acute administration of MCH to the AcbSh of adult pmch(-/-) rats elevated feeding behavior towards wild type levels. Finally, adult pmch(-/-) rats showed increased ex vivo electrically evoked dopamine release and increased limbic dopamine transporter levels, indicating that chronic loss of Pmch in the rat affects the limbic dopamine system.Our findings support the MCH-MCH1R system as an amplifier of consummatory behavior, confirming this system as a possible target for the treatment of obesity. We propose that MCH-mediated signaling in the AcbSh positively mediates motivational aspects of feeding behavior. Thereby it provides a crucial signal by which hypothalamic neural circuits control energy balance and guide limbic brain areas to enhance motivational or incentive-related aspects of food consumption.