Quantification of Reproductive Hormones in Hair of Captive Adult Brown Bears and Their Application as Indicators of Sex and Reproductive State

January 2017 in “ Conservation physiology ”

Marc Cattet, Gordon Stenhouse, David M. Janz, Luciene Kapronczai, Joy A. Erlenbach, Heiko T. Jansen, O. Lynne Nelson, Charles T. Robbins, John Boulanger

testosterone progesterone estradiol cortisol enzyme-linked immunoassays hormone concentrations hair growth cycle reproductive events hormone deposition non-invasive genetic sampling ELISA hormone levels hair cycle reproductive cycles hormone levels in hair non-invasive sampling

From the encyclopedia

Estradiol →

an estrogen promoting hair regrowth more commonly used in women

Hydrocortisone →

a synthetic cortisol used for anti-inflammatory effects

Studysummary This study found that measuring reproductive hormone levels in brown bear hair may effectively support non-invasive genetic sampling, though larger samples or more sensitive techniques are needed for broader application. Our plain-language summary of this paper — not a Tressless recommendation.

In a study involving 94 hair samples from eight captive adult brown bears over two years, researchers developed procedures to measure reproductive steroid hormone concentrations in hair using enzyme-linked immunoassays. They investigated the relationships between testosterone, progesterone, estradiol, and cortisol levels in hair, the impact of hair collection methods (shaving vs. plucking), and the potential of hormone profiles to identify sex and reproductive status. The study found that the required sample size (125 mg of guard hair) for hormone assays was larger than what is typically collected non-invasively, indicating a need for improved collection methods or more sensitive lab techniques. Hormone concentrations were highly correlated, suggesting they reflect physiological processes, and varied with the hair growth cycle and reproductive events, similar to patterns seen in blood serum. However, differences in hormone levels between plucked and shaved samples indicated multiple sources of hormone deposition in hair. The findings suggest that measuring hair hormone levels could enhance non-invasive genetic sampling for brown bear conservation and research, but further validation with free-ranging bears of all sexes, ages, and reproductive states is needed.

View this study on academic.oup.com →

Discuss this study in the Community →

Research cited in this study

16 / 16 results

research Comparison of Methanol and Isopropanol as Wash Solvents for Determination of Hair Cortisol Concentration in Grizzly Bears and Polar Bears

21 citations , January 2017 in “MethodsX”

This study found that methanol is more effective than isopropanol at removing external cortisol from grizzly bear hair and suggests that the choice of solvent can influence hair cortisol concentration results.

research Skin Steroidogenesis in Health and Disease

47 citations , September 2016 in “Reviews in endocrine and metabolic disorders”

This review discusses the steroidogenic properties of human skin and suggests that impaired steroidogenesis may be linked to conditions like acne, rosacea, atopic dermatitis, and androgenic alopecia, but reports no new clinical results.

research Influence of External Factors on Hair Cortisol Concentrations

69 citations , May 2016 in “General and Comparative Endocrinology”

This study found that hair cortisol concentrations in sheep were significantly increased by extensive brushing or dexamethasone treatment, suggesting that external factors may affect its reliability as a chronic stress measure.

research Sources of Variation in Hair Cortisol in Wild and Captive Non-Human Primates

44 citations , February 2016 in “Zoology”

This study observed that hair cortisol concentrations in primates are influenced by factors such as age, sex, hair growth rates, and sampling methods, which must be accounted for in research designs.

research Analysis of Hair Cortisol Levels in Captive Chimpanzees: Effect of Various Methods on Cortisol Stability and Variability

47 citations , January 2016 in “MethodsX”

This study found that while the reproducibility of hair cortisol measurements in captive chimpanzees was high, the fineness of homogenized hair, sample weight, and extraction time influenced absolute cortisol concentrations.

research The Modulatable Stem Cell Niche: Tissue Interactions During Hair and Feather Follicle Regeneration

66 citations , July 2015 in “Journal of Molecular Biology”

This review discusses how macro-environmental factors such as intradermal adipose tissue and sex hormones influence hair and feather stem cell niches, suggesting environmental targets for regenerative medicine, but reports no new clinical results.

research The Circadian Clock in Skin

127 citations , January 2015 in “Journal of Biological Rhythms”

This review discusses the role of the circadian clock in skin functions such as cell proliferation and UV protection and reports no new results; the authors note its potential in studying immune regulation and seasonal behaviors.

research Quantifying Long-Term Stress in Brown Bears with Hair Cortisol Concentration: A Biomarker That May Be Confounded by Rapid Changes in Response to Capture and Handling

90 citations , July 2014 in “Conservation Physiology”

This study found that hair cortisol concentration in free-ranging brown bears is influenced by handling methods, body condition, and potentially both short- and long-term stressors.

research Stress and Reproductive Hormones Reflect Inter-Specific Social and Nutritional Conditions Mediated by Resource Availability in a Bear-Salmon System

66 citations , May 2014 in “Conservation Physiology”

This study found that lower salmon availability was associated with higher stress hormone levels in grizzly and black bears, influencing their physiological responses and competitive behaviors.

Sex Steroid Synthesis in Human Skin In Situ: The Roles of Aromatase and Steroidogenic Acute Regulatory Protein in the Homeostasis of Human Skin

research Sex Steroid Synthesis in Human Skin In Situ: The Roles of Aromatase and Steroidogenic Acute Regulatory Protein in the Homeostasis of Human Skin

46 citations , May 2012 in “Molecular and Cellular Endocrinology”

In this study, higher expression levels of aromatase and steroidogenic acute regulatory protein were correlated with increased estrogen synthesis and fewer hair follicles in human skin, suggesting a link to elastic fiber formation and hair growth.

research The Skin as an Endocrine Organ

75 citations , September 2009 in “Dermato-endocrinology”

This review discusses the skin's role in producing hormones and related substances, highlighting their potential in homeostasis and disease management, and reports no new clinical findings.

research The Hair Follicle as an Estrogen Target and Source

159 citations , July 2006 in “Endocrine Reviews”

This article discusses the influence of estrogens on hair follicle growth and metabolism, suggesting a significant role alongside androgens in hair growth control but reports no new clinical results.

Human Scalp Hair Follicles Are Both a Target and a Source of Prolactin, Which Serves as an Autocrine and/or Paracrine Promoter of Apoptosis-Driven Hair Follicle Regression

research Human Scalp Hair Follicles Are Both a Target and a Source of Prolactin, Which Serves as an Autocrine and/or Paracrine Promoter of Apoptosis-Driven Hair Follicle Regression

128 citations , March 2006 in “American Journal of Pathology”

The study found that prolactin expressed in human scalp hair follicles acts as an autocrine modulator, inhibiting hair growth and promoting hair follicle regression, which may contribute to hair loss in hyper-prolactinemia patients.