Stress & Coping Flashcards
(Selye, 1936)
What is stress?
“Stress is the non-specific response of the body to any demand for change”
Stressors
a disruptor of homeostasis, i.e. a chemical or biological agent, environmental conditions, external stimulus or an event that causes a stress response
stimulus
- environmental (e.g. predator)
- social (e.g. divorce, bereavement)
- chemical (e.g. alcohol, drugs, pollution)
- energetic (e.g. extreme exercise)
- reproductive (e.g. pregnancy)
- physical (e.g. capture, handling)
stress response
a suite of physiological and behavioural responses that help to re-establish homeostasis
adaptive and non-specific
homeostasis
a process that maintains the stability of an animal body’s internal environment in response to changes in external conditions
The hypothalamus-pituitary-adrenal (HPA) axis
in response to stress signals
-> hypothalamus releases CRH
-> stimulates anterior pituitary to release ACTH
-> stimulates adrenal gland
-> to release cortisol
-> increase glucose in blood - allows body to react to physiological or physical threat
Hormones from the adrenal glands
glucocorticoids (Cortisol, Corticosterone; mediate behavioural effects of stress)
Epinephrine, Norepinephrine
What are the effects of the acute stress response?
- increased immediate availability of energy (glucose)
- increase oxygen intake
- decreased blood flow to areas not necessary for movement
- blood flow rerouted to muscles
- inhibition of digestion, growth, immune function, reproduction, and pain perception
- enhancement of memory and sensory function
Effect of chronic stress
1. brain
2. immune system
3. heart
4. adrenal gland
5. ovary
6. testis
- Dendritic atrophy, impaired neuro-genesis and synaptic plasticity, enhanced benzodiazepine tone
- Basal immuno-suppression and decreased immune responsiveness to challenge
- Basal hypertension, sluggish response to and recovery from stress, pathogenic cholesterol profile
- Elevated basal levels of glucocorticoids, sluggish response to and recovery from stress, feedback resistance
- decreased levels of gonadal hormones , increased risk of anovulation and miscarriage
- Testicular atrophy, decreased levels of hormones of the gonadal axis
Seasonal & diurnal variation in GCs (Glucocorticoids)
- seasonal fluctuations in GCs (energetically demanding periods) - breeding has higher GCs
- Cortisol awakening response (cortisol peak ~30min after awakening)
(Creel et al., 2013)
difference between social and non-social species with stress?
non-social - population density and GCs
social - dominance, aggression and GCs
What is one coping mechanism to stress?
social support and integration
what can stress directly affect?
health and biological fitness
what are many sources of stress and what do they directly affect?
many sources of stress are social and directly affecting survival and reproduction (in females, in particular)
what can modulate an individual’s stress response?
social partners (main effects, social buffering, glucocorticoid linkage)
Social partner:
Social buffering
positive effect of sociality on GCs in stressful situations (= downregulation of GCs)
Social partner:
main effects
positive effect of sociality on GCs in everyday interactions
Social partner:
Glucocorticoid linkage
bidirectional modulation of partners’ GCs (up- or downregulation; physiological coregulation/synchrony)
social buffering
the ability of a social partner to attenuate an individual’s behavioural and physiological stress response
- documented in numerous mammals
- more recently also in birds
- partner identity (e.g. familiarity, bond strength) & ‘stress status’ important
- buffering ability of partners may depend on life-history stage
social preferences and buffering
(Hennessy et al., 2009)
what are buffering effects associated with in domestic guinea pigs?
with developmental transitions in social preferences
social preference shift from mother-infant pair to unrelated females as grow older
main effects:
sociality and GCs in everyday interactions
(Fürtbauer et al., 2014)
1. overall
2. mating season
3. non-mating season
- sociality with ‘preferred’ partners affects GC levels in everyday interactions (‘main effects’ hypothesis)
- opposite-sex social interactions linked to low cortisol levels
- same-sex social interactions linked to low cortisol levels
(Christensen et al., 2022, 2023 & 2024)
Primate socio-endocrinology 2.0
1. what are knowledge gaps a result of?
2. what does bio-logging allow?
3. what was quantified?
4. what was tested?
5. what was used?
- knowledge gaps on chain events that link sociality and stress (e.g. causality, speed, and flexibility) due to methodological restrictions, i.e. direct observation (-> rates of behaviours)
- bio-logging allows continuous and simultaneous monitoring of multiple interacting individuals (-> absolute time budgets)
- quantified exchange (giving, receiving, and reciprocating) of grooming an evaluate short- and longer-term hormonal causes and consequences (urine vs. faecal GCs)
- we test whether grooming predicts HPA-axis activity in the short- and long-term
- accelerometres
(Christensen et al., 2023)
Grooming from accelerometers
1. type of learning?
2. what was quantified?
3. continuous quantification of what?
- machine learning (random forest model)
- quantified giving and receiving grooming with high precision and recall
- continuous quantification of grooming (durations, frequencies)
(Christensen et al., 2024)
Sociality & HPA activity - Long-term
what was found between grooming and long-term HPA-axis activity?
negative correlation
(Christensen et al., 2024)
Sociality & HPA activity - Short-term
1. more grooming leads to?
2. HPA-axis activity does not predict?
3. results suggest?
- more grooming leads to increased HPA-axis activity in the short-term
- HPA-axis activity (‘stress status’) does not predict grooming
- results suggest a short-term cost for a long-term benefit
Glucocorticoid linkage
the up- or down-regulation of partners’ physiological stress response
Glucocorticoid linkage documented in?
in humans with strong attachment bonds, e.g. parents and children or romantic couples
Glucocorticoid linkage
stronger covariation among?
stressed partners (e.g. domestic violence)
What else has glucocorticoid linkage been shown in?
more recently shown in great tits (Ouyang et al., 2014) & stickleback fish (Fürtbauer & Heistermann, 2016)
What is current work looking into for glucocorticoid linkage?
on dogs and dogs & owners (Solman & Fürtbauer, in prep) and jackdaw pairs (Hahn et al., in prep)
Cortisol linkage in fish
1. unrelated when?
2. covaried when?
- cortisol unrelated when cohabiting
cortisol unrelated when experiencing an unshared stressful environment
- cortisol covaried when sharing a stressful environment
(Hahn et al., in prep)
Corticosterone linkage in jackdaw pairs
(Feather) corticosterone linkage between pair partners
(Solman & Fürtbauer, in prep)
Cortisol linkage between dogs & owners
1. dogs and owners form what?
2. evidence for?
3. in humans, what is a significant predictor of coregulation strength?
4. results?
- form strong attachment relationships
- evidence for cortisol linkage in human-dogs dyads
(Buttner et al., 2015; Cunnigham, 2017; Sundman et al., 2019) - in humans, time spent in close proximity is a significant predictor of coregulation strength
- stronger (salivary) cortisol linkage between dogs and owners when owners spend less time away
