Abstract # 1992 Poster # 75:

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

Relationship between Behavior and Neurochemical Changes in Rhesus Macaques during a Separation Paradigm

S. Spinelli1, M. Schwandt1, K. Erickson2, S. G. Lindell1, J. Schulkin3, P. Gold3, S. J. Suomi4 and J. D. Higley1
1Section of Primate Models of Psychopathology, National Institute on Alcohol Abuse and Alcoholism, NIH Animal Center, Poolesville , Maryland 20837 , USA, 2Mood and Anxiety Disorders Program, National Institute of Mental Health, Bethesda, MD, 3Clinical Neuroendocrinology Branch, National Institute of Mental Health, Bethesda, MD, 4Laboratory of Comparative Ethology, National Institute of Child Health and Human Development, Poolesville, MD
     Rhesus macaques (Macaca mulatta) raised without adults in a group of peers (peer-only rearing, PR) rather than with their mother (mother-reared, MR) have been proposed as a model to study the consequences of early life stress exposure. At 6 months of age, 30 PR and 70 MR monkeys, underwent 4 sequential, 4-day separations from their mothers, in the case of MR infants, and from their same-aged cage-mates, in the case of PR infants. Animals were then reunited with their mothers or peers for 3 days following each 4-day separation. Acute separation periods were first day of the 4-day separation periods. Chronic separation periods were defined as days 2-4. PR animals showed altered monoamine metabolites and stress hormones that persisted later in life. These environmental and biochemical differences were associated with individual differences in temperament and behavior. This study used a factor analysis to relate a range of behaviors, produced by rhesus monkeys during a social separation, to biochemical measures of cerebrospinal fluid metabolites (HVA, 5HIAA and MHPG) and of hormonal blood levels (ACTH and cortisol), and to compare differences between MR and PR animals. Our results showed that during the acute phase of separation, cortisol and distress-calling (p=0.03) were positively correlated in MR animals but not in PR animals. For the PR, but not the MR subjects, high monoamine concentrations were correlated with depression/despair (HVA p=0.02, 5HIAA p=0.001, MHPG p=0.001). These findings suggest differential rearing affects both the risk for depression and its underlying biochemical systems.