title: Oxytocin in the ventromedial hypothalamic nucleus reduces feeding and acutely increases energy expenditure.
abstract: Central oxytocin reduces food intake and increases energy expenditure. The ventromedial hypothalamic nucleus (VMN) is associated with energy balance and contains a high density of oxytocin receptors. We hypothesized that oxytocin in the VMN is a negative regulator of energy balance acting to reduce feeding and increase energy expenditure. To test this idea, oxytocin or vehicle was injected directly into the VMN of Sprague-Dawley rats during fasted and nonfasted conditions. Energy expenditure (via indirect calorimetry) and spontaneous physical activity (SPA) were recorded simultaneously. Animals were also exposed to a conditioned taste aversion test, to determine whether oxytocin's effects on food intake were associated with malaise. When food was available during testing, oxytocin-induced elevations in energy expenditure lasted for 1 h, after which overall energy expenditure was reduced. In the absence of food during the testing period, oxytocin similarly increased energy expenditure during the first hour, but differences in 12-h energy expenditure were eliminated, implying that the differences may have been due to the thermic effects of feeding (digestion, absorption, and metabolic processing). Oxytocin acutely elevated SPA and reduced feeding at doses that did not cause a conditioned taste aversion during both the fed and fasted states. Together, these data suggest that oxytocin in the VMN promotes satiety and acutely elevates energy expenditure and SPA and implicates the VMN as a relevant site for the antiobesity effects of oxytocin.
authors.affiliation: Department of Food Science and Nutrition, University of Minnesota, Saint Paul, Minnesota; Minnesota Obesity Center, University of Minnesota, Saint Paul, Minnesota; and.
authors.forename: Emily E
authors.initials: EE
authors.lastname: Noble
authors.affiliation: Department of Food Science and Nutrition, University of Minnesota, Saint Paul, Minnesota; Department of Medicine, University of Minnesota, Saint Paul, Minnesota; Minnesota Obesity Center, University of Minnesota, Saint Paul, Minnesota; and Minneapolis VA Health Care System, Minneapolis, Minnesota.
authors.forename: Charles J
authors.initials: CJ
authors.lastname: Billington
authors.affiliation: Department of Food Science and Nutrition, University of Minnesota, Saint Paul, Minnesota; Department of Neuroscience, University of Minnesota, Saint Paul, Minnesota; Minnesota Obesity Center, University of Minnesota, Saint Paul, Minnesota; and Minneapolis VA Health Care System, Minneapolis, Minnesota.
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Kotz
authors.affiliation: Department of Food Science and Nutrition, University of Minnesota, Saint Paul, Minnesota; Minnesota Obesity Center, University of Minnesota, Saint Paul, Minnesota; and Minneapolis VA Health Care System, Minneapolis, Minnesota cwang@umn.edu.
authors.forename: ChuanFeng
authors.initials: C
authors.lastname: Wang
mesh_terms: D000818:Animals; D019440:Anti-Obesity Agents / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004435:Eating / Q000187:drug effects; D004734:Energy Metabolism / Q000187:drug effects*; D005215:Fasting; D005247:Feeding Behavior / Q000187:drug effects*; D007276:Injections, Intraventricular; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D010121:Oxytocin / Q000008:administration & dosage*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012528:Satiety Response / Q000187:drug effects; D013997:Time Factors; D014697:Ventromedial Hypothalamic Nucleus / Q000187:drug effects* / Q000378:metabolism
chemical_list: D019440:Anti-Obesity Agents; D010121:Oxytocin
keywords: energy expenditure; feeding; obesity; oxytocin; ventromedial hypothalamus