Radiolabel validation of cortisol in the hair of rhesus monkeys

• Published in: Psychoneuroendocrinology Vol. 97; pp. 190 - 195
• Main Authors: Kapoor, Amita, Schultz-Darken, Nancy, Ziegler, Toni E.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.11.2018
• Subjects: Animals; Behavior, Animal; Cortisol; Cortisone - analysis; Glucocorticoids; Hair - chemistry; Hair cortisol; Hair hormones; HPLC-UV; Hydrocortisone - analysis; Hydrocortisone - blood; Hypothalamo-Hypophyseal System; Macaca mulatta - metabolism; Male; Pituitary-Adrenal System; Radiolabel; Saliva - chemistry; Tritium; Validation; Validation; Radiolabel; Cortisol; HPLC-UV; Hair cortisol; Hair hormones
• ISSN: 0306-4530; 1873-3360; 1873-3360
• DOI: 10.1016/j.psyneuen.2018.07.022

•Systemically administered [3H]-cortisol was detected in the hair as cortisol.•Demonstrated for that hair cortisol is representative of circulating cortisol.•[3H]-cortisol was incorporated into hair as cortisone.•[3H]-cortisol was also incorporated into hair as other unknown cortisol metabolites. Analysis of cortisol in hair has become a widespread tool for assessment of hypothalamic-pituitary-adrenal (HPA) axis activity because of its ease of collection and its ability to provide cumulative data over a period of months. In order to meaningfully interpret hair cortisol, however a direct validation by radio-metabolism is required to understand cortisol incorporation into hair. Tritiated [3H]-cortisol was IV administered to adult rhesus monkeys to determine 1) if [3H] is found in the hair after injection of [3H]-cortisol, 2) the growth rate of hair and 3) the form in which cortisol is found in hair. Samples of hair were collected from newly and previously shaved patches at 14-days and 28-days after [3H]-cortisol injection. Hair was processed by external wash, grinding, and hormone extractions. Samples were separated by high-performance liquid chromatography (HPLC) and fractions were collected and radioactivity assessed. We found [3H] incorporated into the hair by the 14-day hair collection and no new radioactivity was found by the 28-day collection. Individual hair growth rate was highly variable between monkeys, indicating that the between-subject hair growth patterns were not consistent. Importantly, for the first time, we showed that systemically administered [3H]-cortisol was found in the hair as [3H]-cortisol and [3H]-cortisone, as well as other glucocorticoid metabolites.