ANALYSIS OF ENDOGENOUS CORTISOL CONCENTRATIONS IN THE HAIR OF RHESUS MACAQUES

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Short-term changes in activity of the hypothalamic-pituitary-adrenocortical (HPA) system are routinely assessed by measuring glucocorticoid or metabolite concentrations in plasma, saliva, urine, or feces. However, there are no current methods for determining long-term (i.e., weeks or months) activity of this system. Herein we describe the development and validation of a simple procedure for measuring cortisol concentrations in the hair of rhesus macaques. This procedure involves two brief isopropanol washes of the hair strands to remove surface contaminants, subsequent powdering of the washed and dried hair, a 24-h methanol extraction followed by evaporation of the solvent and reconstitution of the extract in assay buffer, and finally analysis of the extracted cortisol by a sensitive and specific enzyme immunoassay (EIA). Our results confirm the specificity of the procedure for cortisol, show that proximal and distal segments of hair do not differ in their cortisol concentration. This new procedure should be valuable for assessing baseline HPA activity in non-human primates (and, with appropriate validation, in other species as well) over relatively long periods of time, and also for monitoring chronic stress that might be associated with various experimental manipulation