Stress Response and Immunity: Links and Trade Offs

Stress Response and Immunity: Links and Trade Offs

When environmental conditions deviate from the optimal range, stress ensues. Stress response is a set of reactions that allow the organism to adjust and survive adverse conditions. Stress can be ...
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Brain, Stress, and Immunity Connections

Pp. 380-433 (54)

Nadia Danilova

Abstract

Brain coordinates physiological, immunological, and behavioral responses to stress. A typical stress response is “freeze, fight or flight”. It involves the release of catecholamines by the sympathoadrenal system and activation of the hypothalamopituitary- adrenal (HPA) axis to produce various hormones that prepare the organism for a particular response. Stress generally leads to a strong suppression of the adaptive immune system and a partial suppression of the innate immune system. The brain controls the immune organs through hormones produced by the HPA axis and through direct control by neurotransmitters. In turn, immune mechanisms affect behavior and brain development. Brain microglia support developing neurons, phagocyte dead and inactive cells, and participate in the formation of connections between neurons through synaptic pruning. Peripheral immune cells regulate neurons through neurotransmitters and inflammatory mediators such as IL6, TNF, PGE2, histamine, and others. These mediators induce sickness behavior during illness. They also alter the developing brain during maternal stress, maternal immune activation, and early life stress predisposing the brain to a mental illness. Immune mechanisms contribute to psychiatric and neurodegenerative disorders.

Keywords:

Alpha 7 nicotinic acetylcholine receptor, Blood-brain barrier, Corticotropin-releasing hormone (CRH), Depression, Hypothalamic-pituitar- -adrenal (HPA) axis, Hypothalamus, Inflammatory reflex, Microglia, Nociceptors, Neurodevelopment, Neurodegenerative diseases, Neural reflex, Psychological stress, Proopiomelanocortin, Synapse pruning, Sickness behavior, Vagus nerve.

Affiliation:

Department of Molecular Cell & Developmental Biology, University of California, Los Angeles CA, USA.