Abbot et al., 2003 Kyle Nash May 12 th , 2009

1. Are Subordinates Always Stressed?A comparative analysis of rank differences in cortisol levels among primates Abbot et al., 2003 Kyle Nash May 12th, 2009

2. Agenda • Stress and HPA axis review • from Kloet, Joels & Holsboer, 2005 • Abbott et al., 2003 • Intro • Method • Results • Conclusion • Discussion

3. What is Stress? • Process: Stimulus  Response • Stressor: • Stimulus that threatens animal’s physiological homeostasis (Kloets et al., 2005) • Physical vs. Psychological (Real vs. Predicted) • Stress Response: • Active maintenance of physiological homeostasis • Sympathetic (Fight or Flight) & Hypothalamic-Pituitary-Adrenocortical (HPA) systems

4. Fight or Flight Response Stressor Sympathetic Nervous System/ Catecholamines ‘Fight or Flight’

5. Stressor Brain Stem (e.g. LC) ‘Limbic’ System PVN http://www.biology.ucr.edu/people/faculty/Garland/HPA_axis.jpg

6. Corticosteroid Receptors • Two types – Both respond to corticosteroids • Minerocorticoid Receptor (MR): • Appraisal, initial stress response • Important in gene transcription activity • More sensitive corticosteroids (10x) • Glucocorticoids Receptor (GR): • Terminates stress response for recovery (i.e. decrease CRH production) • Increased sensitivity to corticosteroids during stress • High density in PVN, aminergic & limbic pathways • Promotes stressor-related memory storage

9. MR x GR

10. Chronically Stressed Animal • Prolonged and/or repeated exposure to stressor (i.e. prolonged increase in corticosteroids) can have maladaptive consequences • Hypertension, type-II diabetes, ulcers, etc. • Chronic stress Neuroendocrine change • hippocampal (CA3) atrophy, reduced proliferation (MR) • GRs and MRs downregulated • Diminished Denate Granule cell turnover rate • Reduced 5-HT receptor function • Reduced LTP/Facilitated LTD • Produce a Stress-typology • ‘Coping’ can disrupt maladaptive changes • offspring of ‘caring’ rat mothers, higher hippocampal GR gene expression and decreased anxiety-related behaviour • Stress experience (stressors and coping) and genetic background cause long-term changes

11. Summary • Stressors activate sympathetic and HPA systems • Glucocorticoids regulate stress response through MR and GR interaction • Prolonged stress  physiological problems and neuroendocrine funtioning • Individual differences in genetics and experience important in stress response

12. Rank and Stress • Stress levels may be higher in subordinates • Low access to resources, physical and social stressors, low ‘coping’ opportunities • Certain subordinate primates • elevated glucocorticoids and catecholimines • higher blood pressure • Stress-related pathologies • Not consistent for all primates

13. Abbot et al., 2005 • Conflicting results on rank and stress • Purpose • Survey researchers (quasi-meta-analysis) • Rank, Sex, Species  Stress • Looked at both physical/psychological factors

14. Method • Questionnaire: 6 Domains, 17 questions • What is it like to be a dominant individual in this society? • What is it like to be a subordinate individual in this society? • What are the typical routes by which ranks change? • What is the nature of revolutionary change in hierarchies? • The role of kinship. • Non-agonistic factors relevant to the stress-response. • 0 (Not at all) – 3 (Highly applicable)

15. Method: Sample 4 Old world (e.g. Rhesus) 3 New World (e.g. Marmoset) • Subordinates: indicated by expert of each sample • Analyses: by species and sometimes sex • 10 groups in total, large variance in group dynamics

16. Method • DV: Relative Cortisol • Basal levels • Circulatory or urinary • Relative to dominant monkeys, controls for species differences • i.e. 100% = equal cortisol levels

17. Analyses • Two types of analysis • Multiple Regression with independent contrasts • Flips variables from dependent (i.e. similar species) to independent • After data collection, excluded questions based on • missing values (5) • High r’s with other questions or Low r’s with cortisol (4) • 8 total questions • Data Tree - decision algorithm from response variability predicted • Different excluded values • Used 4 questions from 8 (above) in regression

18. Tree-Based Method – Single Branch • (1) If Question 1A is >X, then this predicts relative cortisol levels = Y1% (branch 1). • (2) If Question 1A is <X, then this predicts relative cortisol levels = Y2% (branch 2). • Overall Tree = Minimum Branches for Maximum Predictive Power Q 1A Y1 Y2

20. Final Q’s Multiple Regression • 1A: How much of a role does aggression play in the attainment of dominance? • 2A: How frequently are subordinates subject to stressors? • 2B: How available is social support for subordinates? • 2F: Overall, how much should subordinate status be thought of as an undesirable state actively imposed by more dominant animals? • 3A: Do animals rise in the hierarchy through strenuous challenge of the status quo? • 4A: How often do such “revolutions” occur? • 5A: How important is kinship in understanding interactions among these animals? • 6A: Are there circumstances in which one has to invoke a physiological adaptation to subordinate status, rather than a response to agonistic behavior, to make sense of the profile of a particular stress hormone? • Two significant predictors, 2A and 2B

21. Results: 2A - Social Stressors

22. 2B - Social Support

23. Final Q’s for Tree-Based Analysis • 2A: How frequently are subordinates subject to stressors? • 2B: How available is social support for subordinates? • 3A: Do animals rise in the hierarchy through strenuous challenge of the status quo? • 5A: How important is kinship in understanding interactions among these animals?

25. Discussion • Subordinates do not always express higher levels of cortisol • Important factors: • Stressors frequency • Social support • Relevance of kinship • Possible neuroendocrine mechanisms • Increased stressors  decreased GRs  diminished negative feedback in stress response  cortisol • Outlets (social support) diminishes cortisol levels • Kinship variable could predict both stressor frequency and social support quality

26. Problems • Relative measure of cortisol • consider the cortisol levels for dominant monkeys • Questionnaire • Exclusions were largely subjective • Authors were respondents

27. Discussion • Other important factors? • Other outlets or displacement behaviours? • Simple stressor disruption? • i.e., allowing rats access to a running wheel decreases the magnitude of the glucocorticoid response to shock • Coping mechanisms: MRxGR? • Stops GR downregulation? • Stressor controllability inhibits behavioural response Coping? Social Support?

28. References • Unless otherwise noted, figures and tables from Abbot et al., 2003. • Sapolsky, R.M., Krey, L., McEwen, B., (1984). Stress down-regulates corticosterone receptors in a site-specific manner in the brain. Endocrinology, 114, 287–292. • Kloet, Joels, & Holsboer, (2005). Stress and the brain: From adaptation to disease. Nature Reviews: Neuroscience, 6, 463-475. • http://www.biology.ucr.edu/people/faculty/Garland/HPA_axis.jpg