Neurobiology of aging
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Neurobiology of aging · Sep 2002
ReviewSex, stress and the hippocampus: allostasis, allostatic load and the aging process.
The adaptive responses of the body that maintain homeostasis in response to stressors can be called "allostasis", meaning "achieving stability through change". Mediators produced by the immune system, autonomic nervous system (ANS) and hypothalamo-pituitary-adrenal(HPA) axis produce allostasis. The brain also shows allostasis, involving the activation of nerve cell activity and the release of neurotransmitters. ⋯ EAA and NMDA receptors are also involved in neuronal death that is caused in pyramidal neurons by seizures, by ischemia and by severe and prolonged psychosocial stress. The aging brain seems to be more vulnerable to such effects, although there are considerable individual differences in vulnerability that can be developmentally determined. Moreover, the brain retains considerable resilience in the face of stress, and estrogens appear to play a role in this resilience. "Resilience is an example of successful allostasis in which wear and tear is minimized, and estrogens exemplify the type of agent that works against the allostatic load associated with aging." This review discusses the current status of work on underlying mechanisms for protection and damage.