Title: Protective and Damaging Effects of Stress Mediators (Stress and the Immune System) Chapter Four
1Protective and Damaging Effects of Stress
Mediators(Stress and the Immune System)Chapter
Four
- Caitlin Cleary
- June 13, 2007
http//www.kf6nvr.net/blog/archives/images/computi
ng_stress.jpg
2Psychoneuroimmunology
- Scientific field investigating the link between
bidirectional communications among the nervous
system, endocrine and immune systems - What are the implications of these linkages for
physical and mental health? - - Stress!!!
3What is stress?
- A specific response by the body to a stimulus
that disturbs or interferes with normal
physiological equilibrium/homeostasis - Stressors can be real, imagined, internal or
external - Physical/environmental
- Natural disasters
- Major life changes (good and bad)
- Hassles/day-to-day aggravations
- Personality related
4Stress - cross talk between CNS and immune system
- The brain is the master controller of the
nervous, endocrine, and immune system - However, the brain is also a target for these
systems - Subject to both protection and damage
5New Terms
- Allostasis superordinate system by which
stability is achieved through change - Primary mediators HPA axis, catecholamines, and
cytokines - When set homeostatic points are out of
boundaries, it is referred to as allostatic
states (ex. hypertension, cytokines increasing
risk for autoimmune/inflammatory disorder) - Allostatic load and allostatic overload the
cumulative wear and tear on the regulatory
systems of the brain and body from the cumulative
result of an allostatic state
6Peripheral Limbs of the Stress System Part One
HPA axis hypothalamic-pituitary-adrenal axis
which regulates body processes including
digestion, immune system, mood/sexuality, energy
usage Regulates hormone levels and maintains
homeostasis
http//cti.itc.virginia.edu/psyc220/kalat/JK367.f
ig12.6.HPA_axis.jpg
7Peripheral Limbs of the Stress System Part Two,
Autonomic Nervous System
- Involuntary activities that maintain homeostasis
i.e., cardiovascular, respiratory, and
digestive functions, etc. - Sympathetic and Parasympathetic branches that
work complementary to each other
http//www.buteyko.co.nz/asthma/facts/images/nervo
us.jpg
8Normal Stress Response
Prey sees a predator The event initiates stress
response The prey is able to escape
predation Stress response dissipates and body
returns to homeostasis Fight or Flight or Tend
and Befriend
9Complicated Stress Interactions
10Stress induces change for adaptation
- Behavioral/Psychological (changes to eating,
sleeping patterns, mood, etc.) - Physiological (increased blood pressure, heart
rate, dry throat, etc.) - Immunological (suppression of immune system)
11The General Adaptation Syndrome
- Hans Selye (1936)/ Cannon (1932) the general
adaptation syndrome, a classic, stereotyped
theory of stress - Alarm reaction adrenal medulla releases
epinephrine, and the adrenal cortex produces
glucocorticoids, promoting adaptation and
restoring homeostasis (allostasis) - Resistance defense and adaptation are optimal
(allostatic load) - Exhaustion persistence of stress response
which may lead to illness or death (allostatic
overload)
12Chronic Stress Effects
- Consistently elevated cortisol and catecholamine
levels (Stress response chronically activated) - Non immune related Diabetes, insomnia,
myocardial infarction - Stressful events predispose to disease and immune
deregulation infection, cancer, autoimmune
diseases (ms) - Impaired learning atrophy in hippocampus
- Depression (resulting from altered immune
function)
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14Non-immune related allostatic overload
- Glucocorticoids regulate behaviors that control
energy input and expenditure - - energy conversion serves the body well in the
short term - - elevated insulin levels (glucose uptake) and
glucocorticoids promotes deposition of body fat
and the formation of atherosclerotic plaques in
the coronary arteries in the long term
15Immune related allostatic overload
- These glucocorticoids can modulate the immune
system by lowering the Th1 response and
increasing the Th2 response (diminishing cell
mediated immune response) - Cortisol, a specific glucocorticoid, and
catecholamines can cause changes in
proliferation, cytokine secretion, antibody
production, cellular trafficking, and cytolytic
processes - It has been shown that adding CRH in vivo causes
NK cell cytotoxicity to go down - Clinical administration of glucocorticoids, such
as cortisol, cause eosinophil and lymphocyte
numbers to decrease - Products of the Immune system also can react with
the HPA axis. IL-1, a cytokine produced by the
immune system to mediate inflammation, causes
ACTH release indirectly by increasing CRH
16QUESTIONS?