A preliminary description of responses of free-ranging rhesus monkeys to brief capture experiences: Behavior, endocrine, immune, and health relationships

A cohort of free-ranging rhesus monkeys has been followed since birth in 1994 on the island of Cayo Santiago, Puerto Rico. At 3 years of age, subjects were trapped and blood samples were collected after capture and prior to release the following day. Blood samples were processed for natural cytotoxicity toward xenogeneic tumors, phenotyping, and plasma hormones. Intestinal parasites were determined from fresh stool samples collected during trapping. Data were also available from the previous year for antibody titers to latent viruses prevalent in this population. Behavioral traits of each monkey were characterized using a previously developed trait scale for rhesus monkeys. Natural cytotoxicity toward both K562 and Raji targets declined from capture until release the following day. Plasma cortisol rose and plasma prolactin and growth hormone fell during the period of captivity; a rise in insulin was significant. It was expected that individual differences in behavioral traits might predict immune and hormone levels at the time of capture or changes in these parameters during the capture period. Although behavioral adjectives tended to cluster along three orthogonal dimensions (Insecurity, Irritability, and Sociability), they bore no relationship to the physiological parameters collected acutely (in vitro immune and endocrine parameters). The individual difference markers of gender and maternal rank were not related to the magnitude of the observed changes in these in vitro parameters, either. However, an in vivo measure (CMV titer) was related to individual differences in Irritability. It was concluded that the magnitude of the stress associated with capture overwhelmed the individual difference effects.