Oxytocin Secretion is Related to Energy Availability and Expenditure in Young Female Athletes

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: MON 515-547-Female Reproductive Endocrinology
Monday, June 17, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board MON-546
Elizabeth A Lawson*, Kathryn Elizabeth Ackerman, Meghan Slattery, Dean A Marengi, Lisa Pierce, Gabriela Guereca and Madhusmita Misra
Massachusetts General Hospital/Harvard Medical School, Boston, MA
Oxytocin is a peptide hormone that has been implicated in the modulation of energy metabolism in animal models. Oxytocin knockout mice, for example, develop obesity without a change in food intake, suggesting that a lack of oxytocin may reduce metabolic rate and energy expenditure. On the other hand, administration of central oxytocin reduces food intake in wild-type rats, and this effect is reversed by an oxytocin antagonist, suggesting that oxytocin may be an appetite-regulating hormone and impact energy intake. Additionally, the anorexigenic hormone, peptide YY (PYY), stimulates oxytocin secretion. We have recently demonstrated that young female athletes (in a higher energy expenditure state than non-athletes) have low nocturnal oxytocin secretion compared with non-athletes. Whether oxytocin is associated with measures of energy availability, energy expenditure or other appetite-regulating hormones in athletes is not known. We therefore examined the relationship between fasting morning levels of oxytocin and these measures in 15 normal-weight amenorrheic athletes, 15 eumenorrheic athletes and 15 nonathletic young women 14-21 years old. Although oxytocin levels did not differ between groups, within athletes, oxytocin secretion was positively correlated with measures of energy availability, including weight (r=0.44, p=0.01), BMI (r=0.37, p=0.04) and body fat (r=0.42, p=0.02). Furthermore, oxytocin levels were positively associated with resting energy expenditure (r=0.71, p<0.0001), independent of lean body mass. Oxytocin levels were also associated with nocturnal levels of the anorexigenic hormone, PYY (r=0.40, p=0.03). In non-athletes, oxytocin secretion was significantly correlated with PYY levels (r=0.66, p=0.008), but not measures of energy availability or expenditure. We conclude that in healthy athletic and nonathletic young women, there is a relationship between secretion of anorexigenic peptides PYY and oxytocin. In athletes, oxytocin secretion is also associated with measures of energy availability and expenditure, suggesting that oxytocin may be involved in regulation of energy balance in states of increased physical activity. Further studies will be important in determining the role of oxytocin in appetite and energy homeostasis in humans.

Nothing to Disclose: EAL, KEA, MS, DAM, LP, GG, MM

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm

Sources of Research Support: NIH Grants UL1 RR025758, R01 HD060827, and K23 MH092560; Massachusetts General Hospital Claflin Distinguished Scholar Award.