Urinary 17-OHCS response of high- and low-aggressive rhesus monkeys to shock avoidance

This two-part study was designed to explore the hypothesis that a rhesus monkey's aggressive behavior may be predictive of his adrenal cortical response to shock avoidance. In Part I, the relative aggressiveness of the animals was estimated and they were exposed to four weeks of free operant avoidance. Urinary 17-OHCS output was used as a measure of stress. The results show that the high-aggressive monkeys are chronically stressed and take longer to learn the task. The low-aggressive animals show little stress response and learn the task quickly. In Part II the avoidance paradigm was altered in order to study the possible confounding effects of two variables: initial training time and physiological lability. The results show that the difference in 17-OHCS levels between the two groups is chronic and stable and is not necessarily a function of either of these extraneous variables. The stable differences in 17-OHCS output were interpreted as being a function of the interaction of a particular type of subject and a particular type of task.