OR40-2 Oxytocin Reduces Caloric Intake in Men

Program: Abstracts - Orals, Poster Previews, and Posters
Session: OR40-Obesity: Human Studies in Body Weight Regulation
Sunday, March 8, 2015: 9:30 AM-11:00 AM
Presentation Start Time: 9:45 AM
Room 30A (San Diego Convention Center)
Elizabeth A. Lawson, MD, MMSc1, Dean A. Marengi, BS1, Rebecca L DeSanti1, Tara M Holmes2, David A Schoenfeld, PhD1 and Christiane J Tolley, NP1
1Massachusetts General Hospital/Harvard Medical School, Boston, MA, 2Massachusetts General Hospital/Harvard Medical School
Background: In animal models, the hypothalamic peptide hormone, oxytocin (OT), is anorexigenic. Central OT administration in rats reduces food intake; this effect is reversed by an OT antagonist. Preclinical studies also indicate that OT has beneficial metabolic effects. OT’s effect on nutritional intake and metabolism in humans is unclear. We hypothesized that single-dose intranasal administration of OT would reduce caloric intake in men (primary endpoint). We also hypothesized that OT would reduce appetite and alter levels of appetite-regulating hormones. Finally, we explored metabolic effects of OT.

Methods: We performed a randomized, double-blind, placebo-controlled crossover study of single-dose administration of intranasal OT (24 IU) in 25 healthy men (13 normal-weight and 12 overweight or obese). After receiving OT/placebo (fasting visits, order randomized), subjects selected breakfast from a menu and were given double portions. Caloric content of food consumed was measured. Visual analogue scales were used to assess appetite and fasting blood draws were performed for appetite regulating hormones (leptin, ghrelin, and peptide YY), insulin and glucose before and after OT/placebo. Indirect calorimetry was used to measure resting energy expenditure (REE) and substrate utilization.

Results: Mean age was 27.1±1.5 (mean±SEM) years old. Recorded food intake in the 72 hours leading up to OT and placebo visits did not differ within subjects. Intranasal OT reduced caloric intake at the breakfast meal by 122±51 kcal (p=0.03). OT preferentially decreased consumption of fat (-8.7±3.8 g, p=.03; NS after controlling for multiple comparisons). Group (NW vs. OB) did not affect results. There was no effect of OT on appetite or appetite-regulating hormones. While REE was not impacted by OT, RQ was reduced (p=0.02). OT decreased carbohydrate utilization (p=0.03) and increased fat utilization (p=0.04). In addition, OT reduced average insulin levels over the three time points (-1.7±0.8 uU/mL, p=0.04), but had no effect on glucose levels, indicating an increase in insulin sensitivity. There were few adverse events in the study, none of which was severe, with no difference between OT and placebo conditions.

Conclusions: A single dose of intranasal OT reduces caloric intake and has beneficial metabolic effects in men without concerning side effects. The efficacy and safety of sustained OT administration in the treatment of obesity warrants investigation.

Nothing to Disclose: EAL, DAM, RLD, TMH, DAS, CJT

*Please take note of The Endocrine Society's News Embargo Policy at https://www.endocrine.org/news-room/endo-annual-meeting

Sources of Research Support: NIH Grants K23 MH092560, 1UL1 TR001102-01 (Harvard Catalyst), 2P30DK046200 (Boston Nutrition Obesity Research Center); Massachusetts General Hospital Claflin Distinguished Scholar Award.