Abstract # 81:

Scheduled for Thursday, August 17, 2006 07:00 PM-09:00 PM: Session 8 (Regency West 1/3 ) Poster Presentation

Maternal Behavioral Interactions and Stress Reactivity in Infants of Differentially Reared Rhesus Monkeys (Macaca mulatta)

A. M. Ruggiero1, P. G. Roma2, M. L. Schwandt3, J. D. Higley3 and S. J. Suomi1
1Laboratory of Comparative Ethology, NICHD, Poolesville, MD, USA, 2Department of Psychology, American University, Washington, DC, 3Laboratory of Clinical and Translational Studies, Primate Unit, NIAAA, Poolesville, MD
     Few investigations have explored effects of contemporary rearing paradigms on parenting behavior. Even less is known about how early rearing and consequent maternal behaviors may influence biobehavioral development in offspring. The present study investigated mother-infant behavioral interactions and infant stress reactivity in 120 mother-infant pairs of rhesus macaques (Macaca mulatta). The mothers themselves were either mother-reared (MR, n=62), surrogate-peer reared (SPR, n=26), or peer-reared (PR, n=32). Focal observations of each mother-infant pair were conducted for a total of 10 minutes/week from weeks 1-24 post-natal. Isolation stress tests of the infants were conducted on Days (D) 14 & 30 and Months (M) 3-5 post-natal (with a baseline assessment at M2), and a standard 4-week separation regimen was conducted between M6-8; blood samples were obtained throughout these procedures via femoral venipuncture. All procedures took place between 1100 hr and 1400 hr. Fisher’s LSD tests showed PR mothers grooming their infants more than MR mothers during M4 and M6, but rejecting their infants more than both other groups during M3 and M5 (ps<0.05). SPR mothers engaged in more mutual ventral contact versus MR females during M1, and versus MR and PR mothers during M4 (ps<0.02). Concordantly, infants of SPR mothers produced less cortisol when stressed versus infants of MR and PR mothers at D14, and versus MR infants at D30, but also showed higher baseline cortisol levels at M2 versus MR infants (ps<0.05). No differences in cortisol during separations were observed (ps>0.24); however, SPR infants produced lower peak ACTH levels than MR infants (p<0.02). The results reveal effects of early rearing on adult maternal behaviors and non-genomic transmission of rearing effects across generations, but no enduring consequences of maternal rearing condition on infant biobehavioral development.