Heritability and genetic correlation of hair cortisol in vervet monkeys in low and higher stress environments

Abstract

SummaryChronic activation of the hypothalamic-pituitary adrenal (HPA) system is a risk factor for a variety of physical and mental disorders, and yet the complexity of the system has made it difficult to define the role of genetic and environmental factors in producing long term individual differences in HPA activity. Cortisol levels in hair have been suggested as a marker of total HPA activation over a period of several months. This study takes advantage of a pedigreed nonhuman primate colony to investigate genetic and environmental influences on hair cortisol levels before and after an environmental change. A sample of 226 adult female vervet monkeys (age 3-18) living in multigenerational, matrilineal social groups at the Vervet Research Colony were sampled in a stable low stress baseline environment and 6 months after the entire colony was moved to a new facility with more frequent handling and group disturbances (higher stress environment). Variance components analysis using the extended colony pedigree was applied to determine heritability of hair cortisol levels in the two environments. Bivariate genetic correlation assessed degree of overlap in genes influencing hair cortisol levels in the low and higher stress environments. The results showed that levels of cortisol in hair of female vervets increased significantly from the baseline to the post-move environment. Hair cortisol levels were heritable in both environments (h 2 = 0.31), and there was a high genetic correlation across environments (rhoG = 0.79), indicating substantial overlap in the genes affecting HPA activity in low and higher stress environments. This is the first study to demonstrate that the level of cortisol in hair is a heritable trait. It shows the utility of hair cortisol as a marker for HPA activation, and a useful tool for identifying genetic influences on long term individual differences in HPA activity. The results provide support for an additive model of the effects of genes and environment on this measure of long term HPA activity.

Chronic stress in the mother-infant dyad: Maternal hair cortisol, infant salivary cortisol and interactional synchrony

“…Mother-infant interaction quality is one of several possible explanations for the association of maternal HCC with infant HPA function, and these mechanisms are not mutually exclusive. There is a genetic contribution to salivary cortisol levels (Kudielka et al, 2009; Wust et al, 2004), and heritability of HCC has been demonstrated in vervet monkeys (Fairbanks et al, 2011). It is possible that this heritable component of cortisol is more pronounced in hair cortisol, because large portions of the variance are not explained by time-of-day and day-to-day fluctuations, as is the case for salivary measures.…”

Maternal Influence on Child HPA Axis: A Prospective Study of Cortisol Levels in Hair

“…The children' s cortisol concentrations in hair showed a linear association over time and at the ages of 1, 3, 5, and 8 years, suggesting that the physiologic stress response has a set point and 26 ; other examples are studies on twins, which suggest high heritability in response to a low-anxiety context, and on polymorphism of the corticoid receptor gene. 27,28 One could also hypothesize that there is an environmental association, maybe promoting the child' s development of behavioral and physiologic regulatory systems.…”

Population density-dependent hair cortisol concentrations in rhesus monkeys (Macaca mulatta)

“…Studies utilizing hair cortisol have shown that HCCs decline during the first several years of life in several nonhuman primate species including rhesus monkeys (Dettmer et al, 2012; Feng et al, 2011), vervets (Laudenslager et al, 2012), and baboons (Fourie & Bernstein, 2011), and one study also demonstrated sex differences in HCCs in nonhuman primates during puberty and adulthood (Laudenslager et al, 2012). Moreover, several studies in both human and nonhuman primates have demonstrated increases in HCCs in response to stressful events including relocation (in monkeys; Davenport et al, 2008; Dettmer et al, 2012; Fairbanks et al, 2011), unemployment (in humans; Dettenborn et al, 2010), and chronic health conditions (in humans; Thomson et al, 2010; Van Uum et al, 2008). Thus, we sought to utilize the hair cortisol assay to test the hypothesis that population density affects chronic physiological stress in nonhuman primates.…”