Analysis of hair cortisol levels in captive chimpanzees: Effect of various methods on cortisol stability and variability

Yumi Yamanashi,Migaku Teramoto,Naruki Morimura,Satoshi Hirata,Juri Suzuki,Misato Hayashi,Kodzue Kinoshita,Miho Murayama,Gen’Ichi Idani

doi:10.1016/j.mex.2016.01.004

Yumi Yamanashi, Migaku Teramoto + Show 7 more

Open Access

https://doi.org/10.1016/j.mex.2016.01.004

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Abstract

Hair cortisol has been reported to be a useful measure of long-term hypothalamic–pituitary–adrenal (HPA) axis activation in several species. It serves as a practical tool for long-term stress assessment, but it is important to understand the methodological factors that can affects hair cortisol assays to avoid methodological artifacts. To that end, we tested several procedures for measuring cortisol levels in hair collected from captive chimpanzees. The results showed that reproducibility was high, and we found no differences in cortisol levels among the various storage, drying, and sampling methods. However, the fineness of homogenized hair, sample weight, and extraction time affected absolute hair cortisol concentration. Although hair cortisol levels were stable over time, factors that may influence measurement results should be kept constant throughout a study.•We modified and validated a methodology involving enzyme immunoassays to reliably measure the hair cortisol levels of captive chimpanzees.•The results revealed that the fineness of homogenized hair, sample weight, and extraction time caused variations in absolute hair cortisol concentrations in chimpanzees. In contrast, storage, drying, and sampling from similar body parts did not affect the results.

Highlights

Long-term stress may negatively affect animal welfare [7]
The results revealed that the fineness of homogenized hair, sample weight, and extraction time caused variations in absolute hair cortisol concentrations in chimpanzees
Samples were collected from 72 captive chimpanzees (38 males and 42 females) living in the Kumamoto Sanctuary (KS), the Primate Research Institute (PRI), and the Great Ape Research Institute. (For information about care and husbandry of these chimpanzees, see Refs. [2,3,4])

Summary

Introduction

Long-term stress may negatively affect animal welfare [7]. The practical limitations of the methods used have prevented the estimation of longterm stress levels in captive wild animals. We recently developed a hair cortisol assay to monitor long-term stress in captive chimpanzees [1]. It is important that the procedures used to assess the welfare of animals be suitable for implementation in a variety of laboratory settings and that we are able to reliably measure hair cortisol levels over the long term without artifacts. The storage method and duration affect the hormone levels in feces and urine samples [22]. The analysis of hair cortisol involves a number of steps prior to the immunoassay, such as collecting samples from a body region, grinding the samples, and extracting and drying the hormone

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Results

Conclusion