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Allostasis

German: Allostase

1 Definition

Allostasis is the adaptive response of the organism to chronic or extreme strain conditions, which ensures survival in life-threatening situations. Typical examples for allostatic responses include fever, adaptation to stress by increased release of glucocorticoids and the TACITUS syndrome.

2 Mechanisms

The concept of allostasis extends the theory of homeostasis. Originally defined as stability through change it comprises responses of biological feedback control systems that are mediated by changed set points or modified structure parameters. Both mechanisms back up homeostasis, thus enabling survival in extreme situations. This adaptive response requires coordinated action of all involved control mechanisms.

The penalty of allostasis, referred to as allostatic load, is wear and tear (and consecutively ageing). The term allostatic overload denotes acute pathological sequelae of allostatis.

3 Classification

Usually, the following types of allostasis are distinguished:

  • Type 1 allostasis denotes acute adaptive responses to (usually unpredictable) strain, e.g. the metabolism of the starving organism, fever and TACITUS.
  • Type 2 allostasis indicates predictive adaptation to expected (but not actual) energy deficit.

A third form of allostasis occurs in situations of rapidly decreasing strain, e.g. in the refeeding syndrome.

4 Background

The concept of allostasis was first described in 1988 by Sterling and Eyer. McEwen and Stellar considerably expanded the theory in 1993 and subsequently.

5 See also

6 References

  • Sterling, P.; Eyer, J. (1988). "Allostasis: A new paradigm to explain arousal pathology". In Fisher, S.; Reason, J. T. Handbook of life stress, cognition, and health. Chicester, NY: Wiley. ISBN 9780471912699. OCLC 17234042
  • McEwen BS. Stress, adaptation, and disease. Allostasis and allostatic load. Ann N Y Acad Sci. 1998 May 1;840:33-44. PMID 9629234
  • Michael Stumvoll, P. Antonio Tataranni, Norbert Stefan, Barbora Vozarova und Clifton Bogardus. Glucose Allostasis. Diabetes 52:903-909, 2003. DOI 10.2337/diabetes.52.4.903 PMID 12663459
  • Sterling, Peter (2004). "Chapter 1. Principles of Allostasis". In Schulkin, Jay. Allostasis, homeostasis, and the costs of physiological adaptation. New York, NY: Cambridge University Press. ISBN 9780521811415. OCLC 53331074
  • Goldstein DS. Computer models of stress, allostasis, and acute and chronic diseases. Ann N Y Acad Sci. 2008 Dec;1148:223-31. PMID 19120114

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