Psychoneuroimmunology
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Psychoneuroimmunology (PNI) is a specialized field of research that studies the interactions between behavior, the brain, and the immune system of the body. The term was originally coined by Robert Ader and Nicholas Cohen at the University of Rochester in 1975. The placebo effect and psychosomatic disease are part of this subject.
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[edit] Examples of psychoneuroimmunological effects
It has been observed that stressful life circumstances can be linked to impaired immune system function{[1]}. For example,
- Alzheimer's caregivers were more likely to have more severe colds (immune systems were compromised for up to 2 yrs afterwards);
- exam stress lowers the ability to create antibodies to the flu vaccine;
- wound healing is much slower in psychologically stressed adults;
- bereavement: lower lymphocyte proliferation was observed 8 weeks after bereavement;
- divorce: depressed T and NK cell levels;
- unemployment: reduced lymphocyte responses were observed 9 months after losing employment;
- depression: depressed T and NK cell levels, and twice the incidence of cancer (related to the severity of the depression).
Link between stress and disease
Based on the finding that many stress hormones are potent immune modulators.
Including:
- Glucocorticoids
- Corticotropin releasing hormone
- Catecholamines
- Reproductive hormones
[edit] Communication between the brain and immune system
- Stimulation of brain sites alters immunity.
- Stressed animals have altered immunity.
- Immune cells produce cytokines that act on the CNS
- Immune cells respond to signals from the CNS.
[edit] Communication between neuroendocrine and immune system
- Glucocorticoids and catecholamines influence immune cells.
- Endorphins from pituitary & adrenal medulla act on immune system.
- Activity of the immune system is correlated with neurochemical/neuroendocrine activity of brain cells.
[edit] Connections between glucocorticoids and immune system
- Anti-inflammatory hormones that enhance the organisms response to a stressor.
- Prevent the overreaction of the body own defense system.
- Regulators of the immune system.
- Affect cell growth, proliferation & differentiation.
- Cause immunosuppression.
- Suppress cell adhesion, antigen presentation, chemotaxis & cytotoxicity.
- Increase apoptosis.
[edit] Corticotropin-releasing hormone (CRH)
Release of corticotropin-releasing hormone (CRH) from the hypothalamus is influenced by stress.
- CRH is a major regulator of the HPA axis/stress axis.
- CRH Regulates secretion of Adrenocorticotropic hormone (ACTH).
- CRH is widely distributed in the brain and periphery
- CRH also regulates the actions of the Autonomic nervous system ANS and immune system.
Furthermore, stressors that enhance the release of CRH suppress the function of the immune system; conversely, stressors that depress CRH release potentiate immunity.
- Central mediated since peripheral administration of CRH antagonist does not affect immunsuppression
[edit] Reference
- Dr Deborah Hodgson (2006) Psychoneuroimmunology, University of Newcastle
Kiecolt-Glaser Jan K. "Stress, personal relationships, and immune function: health implications." Brain, Behavior and Immunity. 13.1 (Jan 1999): 61-72. PMID: 10371678. Dhabhar Firdaus S. "Stress-induced augmentation of immune function--the role of stress hormones, leukocyte trafficking, and cytokines." Brain, Behavior and Immunity 16.6 (Dec 2002):785-98. PMID: 12480507
[edit] See also
[edit] External link
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