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Obesity is a global epidemic that causes morbidity and impaired quality of life. The melanocortin receptor 4 (MC4R) is at the crux of appetite, energy homeostasis, and body-weight control in the central nervous system and is a prime target for anti-obesity drugs. Here, we present the cryo-electron microscopy (cryo-EM) structure of the human MC4R-G signaling complex bound to the agonist setmelanotide, a cyclic peptide recently approved for the treatment of obesity. The work reveals the mechanism of MC4R activation, highlighting a molecular switch that initiates satiation signaling. In addition, our findings indicate that calcium (Ca) is required for agonist, but not antagonist, efficacy. These results fill a gap in the understanding of MC4R activation and could guide the design of future weight-management drugs.
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http://dx.doi.org/10.1126/science.abf7958 | DOI Listing |
Int J Mol Sci
August 2025
Department of Pediatrics, School of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA.
Oxytocin (OT), traditionally associated with reproduction and social bonding, has emerged as a key modulator of gastrointestinal (GI) physiology and appetite regulation behavior through its actions within the gut-brain axis. Central to this regulation are vagal oxytocin receptors (VORs), which are located along vagal afferent and efferent fibers and within brainstem nuclei such as the nucleus tractus solitarius and dorsal motor nucleus of the vagus. This review presents a comprehensive synthesis of current knowledge on the anatomical distribution, molecular signaling, developmental plasticity, and functional roles of VORs in the regulation of GI motility, satiety, and energy homeostasis.
View Article and Find Full Text PDFNeuron
September 2025
Charité-Universitätsmedizin Berlin, Neuroscience Research Center, Charitéplatz 1, 10117 Berlin, Germany; Charité-Universitätsmedizin Berlin, Einstein Center for Neurosciences Berlin, Charitéplatz 1, 10117 Berlin, Germany; Charité-Universitätsmedizin Berlin, Institute of Cell and Neurobiology
Binge feeding commonly leads to overeating. Experiencing flavor during food consumption contributes to satiation. Still, the interactions between flavor, binge feeding, and food intake remain unknown.
View Article and Find Full Text PDFMol Nutr Food Res
August 2025
Leibniz Institute for Food Systems Biology at the Technical University of Munich, Freising, Germany.
Optimizing plant-based protein intake, such as pea protein hydrolysates (PPHs), may aid in obesity management. This study investigated whether PPHs with varying bitterness and degrees of hydrolysis (DH) differently affect satiety in healthy male participants. In a short-term randomized control trial, 19 moderately overweight men (BMI 25-30 kg/m) consumed boluses of 75 g glucose plus 15 g PPH (control without PPH; PPH1: less bitter, DH = 35%; PPH2: more bitter, DH = 23%).
View Article and Find Full Text PDFAm J Physiol Cell Physiol
September 2025
Department of Integrative Physiology and Neuroscience, College of Veterinary Medicine, Washington State University, Pullman, Washington, United States.
Circadian rhythms are endogenous biological clocks that regulate physiology and behaviors, such as food intake, and are synchronized by the environmental light/dark cycle. The nucleus of the solitary tract (NTS) receives excitatory glutamatergic inputs from vagal afferent neurons that innervate the gastrointestinal tract and are sensitive to the gut peptide cholecystokinin (CCK), which is released following food intake to promote satiation. Previously, we observed that NTS membrane properties, neurotransmission, and action potential firings were all under circadian control.
View Article and Find Full Text PDFMol Metab
July 2025
Institute of Neurobiology, University of Lübeck, Lübeck, Germany; Center of Brain, Behavior & Metabolism, University of Lübeck, Lübeck, Germany. Electronic address:
Objective: The circadian clock anticipates daily repetitive events to adapt physiological processes. In mammals, the circadian system consists of a master clock in the suprachiasmatic nucleus (SCN), which synchronizes subordinate tissue clocks, including extra-SCN central nervous system (CNS) clocks involved in functions such as sleep and appetite regulation. Appetite is controlled by both homeostatic and non-homeostatic (hedonic) circuits.
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