Abstract # 2352 Poster # 37:

Scheduled for Thursday, June 19, 2008 05:00 PM-07:00 PM: Session 4 (Ball Rooms A and B) Poster Presentation

Early adverse rearing experiences alter sleep-wake patterns and basal cortisol levels in juvenile rhesus monkeys (Macaca mulatta)

C. E. Barrett, P. Noble, E. Hanson, D. S. Pine, J. T. Winslow and E. E. Nelson
NIH/NIMH, Bldg 110, Rm 117, 16701 Elmer School Rd, Dickerson, MD 20842, USA
     Monkeys separated from their mothers soon after birth and raised with peers display many alterations in stress responsivity and social and fearful behavior characteristic of mood and anxiety disorders. Although behavioral and emotional disturbances in peer-reared monkeys have been well characterized, and sleep disorders are common in psychiatric disorders, variations in diurnal sleep-wake cycles in differentially-reared animals have not been previously examined. We investigated circadian rhythms in juvenile nursery- and mother-reared rhesus macaques (Macaca mulatta, N=16) using 24h actigraphy measures conducted in the home cage and three daily points of unstressed plasma cortisol levels. Two-sample t-tests revealed that, compared to mother-reared (MR) monkeys, nursery-reared (NR) animals had shorter durations of nocturnal sleep [t(14)=2.81, p<0.05], earlier morning wake times [t(14)=-4.27, p<0.01], and longer periods of sleep during the active period [t(14)=3.32, p<0.01], specifically in the morning [t(14)=3.28, p<0.01]. No shift in circadian cortisol was observed [ANOVA, F(2,26)=2.06, p>0.05], but NR animals displayed an overall elevation compared to MR animals [ANOVA, F(1,13)=5.33, p<0.05]. Post-hoc t-tests revealed that basal cortisol levels were greater in NR monkeys at 1200h [t(14)=-3.02, p<0.05], but no different from MR animals’ levels at 0600h and 1800h [t(13)=-0.890, p>0.05; t(14)=-1.45, p>0.05). These disturbances in sleep-wake behavior may offer insight to the potential neurobiological differences between rearing groups and provide an easily accessible index of stress levels in a juvenile population.