Abstract # 59:

Scheduled for Thursday, June 21, 2007 05:00 PM-07:00 PM: Session 7 (South Main Hall) Poster Presentation

Development of Oxytocin in Young Female Rhesus Monkeys on Cayo Santiago

K. L. Robbins1, P. B. Gray2, M. S. Gerald3, M. L. Laudenslager4 and S. J. Suomi1
1NICHD Laboratory of Comparative Ethology, NIHAC, P.O. Box 529, Poolesville, MD 20837, USA, 2University of Nevada, 3Caribbean Primate Research Center, 4University of Colorado Denver and Health Sciences Center
     Oxytocin has been linked to affiliative behaviors in human and nonhuman primates. The development of oxytocin was studied in a cohort of free ranging young female rhesus monkeys (Macaca mulatta) on Cayo Santiago. During the annual trapping, two blood samples were collected 24 hrs apart on 26 subjects (18 subjects in Year 6) from the ages of three to six. Morphometric measures were collected each year. With the exception of Year 3 when oxytocin levels were very low, the two samples within each year were significantly correlated [r(24)=0.93, r(24)=0.69, and r(16)=0.84 for years 4, 5, and 6, all p<0.001]. There were significant age-related differences in oxytocin levels, with the lowest levels seen in three-year-old females and peak levels in five-year-olds [F(1,3)=24.1, p<0.001]. Age at first reproduction in this cohort was 4 years. For four- and six-year-olds, lactating females had higher oxytocin than non-lactating/non-pregnant females [Yr 4, t(23)=6.91, p=0.02; Yr 6, t(16)=6.21, p=0.020. Among 4-year-olds, weight was positively correlated with oxytocin levels, with reproductive status controlled [r(23)=0.61, p=0.001]. The results suggest larger females may reach puberty earlier, and after puberty there is a modest but consistent stability of individual differences in oxytocin, within and between years. Funded by the NICHD intramural program (KLR, SJS), NIH NCRR CM-20-P40 RR003640, the University of Puerto Rico (MSG) and NIH AA013973 (MLL).