Abstract # 53:

Scheduled for Thursday, June 18, 2015 04:15 PM-04:30 PM: (Cascade E) Oral Presentation


EARLY REARING EXPERIENCE MODULATES TEMPERAMENT AND ACTIVITY OF THE OXYTOCIN SYSTEM AND HYPOTHALAMIC-PITUITARY-ADRENOCORTICAL (HPA) AXIS IN INFANT RHESUS MONKEYS (MACACA MULATTA)

A. F. Hamel1, A. M. Dettmer2, M. M. Miller2, S. J. Suomi2, J. S. Meyer3 and M. A. Novak3
1University of Massachusetts Amherst, Neuroscience and Behavior Graduate Program, Amherst, MA 01003, USA, 2Laboratory of Comparative Ethology, Eunice Kennedy Shriver National Institute of Child Health & Human Development, National Institutes of Health, Poolesville, MD, 3Psychological and Brain Sciences, University of Massachusetts Amherst
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     Early life is a critical period of neuroendocrine development. In macaques, nursery rearing has been shown to dysregulate hypothalamic-pituitary-adrenocortical (HPA) axis activity. Yet, little is known about how rearing experience modifies other neuroendocrine systems, such as the oxytocin system. To assess oxytocin and cortisol concentrations, hair, plasma, and cerebrospinal fluid were collected during routine health exams from 120 (68 male) infant rhesus monkeys (Macaca mulatta) randomly assigned to mother-peer reared (MPR), surrogate-peer reared (SPR), or peer-only reared (PR) conditions. As expected, SPR and PR infants had lower plasma cortisol levels on day 14 (F(2)=16.460, p<0.001) and day 30 (F(2)=11.025, p<0.001) and lower hair cortisol at 6 months of age (F(2)=4.419, p=0.015) than MPR infants. Surrogate-peer reared infants had higher plasma oxytocin levels on day 30 (F(2)=3.847, p=0.029) than PR and MPR infants. Temperament, evaluated during the Brazelton Neonatal Assessment (BNAS), was also modified by rearing. Mother-peer reared infants were more reactive (F(2)=63.985, p<0.001), less consolable (F(2)=157.966, p<0.001), and less able to sooth themselves (F(2)=150.608, p<0.001) while PR infants were more fearful (F(2)=5.480, p=0.005). Blunted plasma cortisol levels in SPR and PR infants support previous reports of dysregulated HPA axis activity in nursery reared monkeys. For SPR monkeys, the oxytocin system may be altered by early experience. Results of the BNAS suggest that MPR infants may respond more reactively to maternal separation and behavioral testing.