Quantification of hair cortisol concentration in common marmosets (Callithrix jacchus) and tufted capuchins (Cebus apella)

Abstract

Quantifying cortisol concentration in hair is a non-invasive biomarker of long-term hypothalamic-pituitary-adrenal (HPA) activation, and thus can provide important information on laboratory animal health. Marmosets (Callithrix jacchus) and capuchins (Cebus apella) are New World primates increasingly used in biomedical and neuroscience research, yet published hair cortisol concentrations for these species are limited. Review of the existing published hair cortisol values from marmosets reveals highly discrepant values and the use of variable techniques for hair collection, processing, and cortisol extraction. In this investigation we utilized a well-established, standardized protocol to extract and quantify cortisol from marmoset (n = 12) and capuchin (n = 4) hair. Shaved hair samples were collected from the upper thigh during scheduled exams and analyzed via methanol extraction and enzyme immunoassay. In marmosets, hair cortisol concentration ranged from 2,710 to 6,267 pg/mg and averaged 4,070 ± 304 pg/mg. In capuchins, hair cortisol concentration ranged from 621 to 2,089 pg/mg and averaged 1,092 ± 338 pg/mg. Hair cortisol concentration was significantly different between marmosets and capuchins, with marmosets having higher concentrations than capuchins. The incorporation of hair cortisol analysis into research protocols provides a non-invasive measure of HPA axis activity over time, which offers insight into animal health. Utilization of standard protocols across laboratories is essential to obtaining valid measurements and allowing for valuable future cross-species comparisons.

Aggression and social support predict long‐term cortisol levels in captive tufted capuchin monkeys (Cebus [Sapajus] apella)

“…The average hair cortisol concentration for the group was 764.5 ± 79.9 pg/mg with a range from 425.7 to 1,787.1 pg/mg (Table ). These levels are consistent with previous measures of hair cortisol in capuchin monkeys using the same methods (Phillips et al, ). Consistent with previous findings that cortisol levels in New World primates are up to 10 times higher than those of Old World primates (Coe, Savage, & Bromley, ), the same hair sample extraction and assay method in rhesus monkeys revealed cortisol levels ranging from 40 to 70 pg/mg (Dettmer et al, ; Wooddell et al, ) compared to our 425–1,787 pg/mg.…”

“…Samples were processed and analyzed for cortisol levels in the laboratory of Dr. Jerrold Meyer at the University of Massachusetts at Amherst. The assay method is detailed in Meyer et al, (large sample method) and has previously been used to measure hair cortisol in a number of nonhuman primate species including rhesus and pig‐tailed macaques, olive baboons, capuchin monkeys, and common marmosets (Davenport, Tiefenbacher, Lutz, Novak, & Meyer, ; Dettmer et al, ; Grant et al, ; Meyer et al, ; Phillips et al, ). Samples were weighed and 50 mg of hair for each subject was isolated for analysis (range, 49.3–50.5 mg).…”

“…The duration of hair growth in capuchin monkeys has not been explicitly measured, but based on previous literature on hair growth in tamarins and approximations of hair growth rate in capuchin monkeys (Dietz, Baker, & Allendorf, ; Phillips et al, ), we estimated the hair growth period in this species to be approximately 6 months.…”

Life in a harsh environment: the effects of age, sex, reproductive condition, and season on hair cortisol concentration in a wild non-human primate

“…There are inconsistent results concerning whether HCC varies by sex in nonhuman primates. Phillips et al (2018) did not detect significant sex differences among captive adult common marmosets (C. jacchus). Similarly, researchers did not find sex differences in HCC in captive chimpanzees (Pan troglodytes) and orangutans (Pongo spp.)…”

“…We treated these samples as independent for analysis because they were collected between 4 and 24 months apart. Based on the length of the shaved hair samples (12-14 mm) used for analysis, and the fact that hair growth in captive marmosets is approximately .5 cm per month (Phillips et al, 2018), we estimate that the HCC represents marmoset physiology during the preceding 8-12 weeks.…”