Cortisol and Catecholamine Concentrations Are Affected by Repeated Relocations of Adult Female Rhesus Monkeys (Macaca mulatta)

In captive primate facilities, relocations—moves, within the facility, from one cage to another—can be common events. On the one hand, relocations are generally regarded as relatively benign events, as past studies have generally shown only transient elevations in cortisol concentrations following relocation. On the other hand, the frequency of relocations has been associated with adverse health and behavioral outcomes. As part of a larger project examining the effects of stress on follicular development, we relocated adult female rhesus monkeys on a weekly basis for several months in each of 3 years, and measured concentrations of urinary cortisol, epinephrine, and norepinephrine, as well as hair cortisol. Results for urinary cortisol and epinephrine were similar: significant elevations immediately following initiation of relocations during Years 1 and 3, and reductions in concentrations by the end of the relocation sequences in Year 1. No changes were seen for these two measures in Year 2. In contrast, elevated norepinephrine concentrations were found for all 3 years. Significant elevations in hair cortisol concentrations were found for Years 2 and 3, and suggested persisting and cumulative effects of relocations on the hypothalamic−pituitary−adrenal axis. Together, these results suggest that relocations may not be the benign events suggested by earlier studies. Given that all organs of the body are innervated by the sympathetic nervous system (the principal source of norepinephrine in blood and urine) and that cells of the body have glucocorticoid and catecholamine receptors, our results suggest possible mechanisms by which repeated relocations may result in adverse health outcomes. Repeated relocations may be a valuable model for experimentally generating moderate stress; however, we encourage colony managers and scientists to minimize such events to enhance the welfare of the animals.