EFFECT OF A PREFERRED COMPANION IN MODULATING STRESS IN ADULT FEMALE RHESUS-MONKEYS

Using a counterbalanced design, seven adult female rhesus monkeys were removed from their social group and housed in a novel environment bot h alone and with a companion chosen on the basis of quantitative affil iative behaviors. Blood samples (n = 2) were collected from all study animals before the exposure to the novel environment, then at 2, 24, a nd 96 h thereafter for cortisol and immunological analyses. During bot h conditions, subjects showed evidence of stress as indicated by eleva ted cortisol concentrations and decreases in absolute numbers of lymph ocyte subsets. There was no significant interaction between condition (alone vs. companion) and time in cortisol percent change and further planned post hoc analyses showed no significant between-condition diff erences for any of the postseparation time points. Similarly, no signi ficant interaction was found between conditions and time for the absol ute number of CD4+CD8- T cells, CD8+CD4- T cells, or CD20+CD2- B cells . However, planned post hoc comparisons showed that subjects in the co mpanion condition exhibited a significantly smaller percent change fro m baseline than in the alone condition at the 24 h and 96 h sample per iods in absolute numbers of CD4+CD8- and CD8+CD4- T cells. Results sho wed that adult female rhesus monkeys exhibited a profound stress respo nse when removed from their social group to a novel environment and th at recovery time of T cell subsets was significantly enhanced by the p resence of a preferred companion.