Adaptation is a fundamental biological concept at the core of evolutionary biology and the process of natural selection. It is also a central feature within the lives of individuals challenged by daily stresses. The adaptation concept has been the object of considerable investigation at multiple levels of organization from the molecular to the ecosystem. This chapter explores how the concept of adaptation is expressed within the framework of the dose–response relationship and its biological and biomedical implications. It is the contention of this chapter that the hormetic dose response is a manifestation of the adaptive response, a relationship that becomes evident when robust study designs with appropriate numbers of doses, proper dose spacing and a temporal framework are employed. However, hormesis is much more than the manifestation of the adaptive response in the clothing of a dose–response relationship. Hormesis will be shown to be the most reliable and generalizable quantitative index of biological plasticity, constraining the magnitude of dose–response relationship as seen in the pharmacological concept of the ceiling effect and resulting from the downstream integration of activation signals from multiple pathways. This mechanistic framework not only accounts for the quantitative features of the hormetic dose response, but achieves this in a manner that can integrate effects from the multiple agents, thereby effectively addressing single and multiple chemical exposure paradigms. While this chapter defines hormesis as a dose response phenomenon which is characterized with a low dose stimulation and a high dose inhibition (Fig. 1) it will be shown to be a fundamental biological concept with extremely broad implications.
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© 2008 Springer Science + Business Media B.V
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Calabrese, E.J. (2008). What Is Hormesis?. In: Le Bourg, E., Rattan, S.I.S. (eds) Mild Stress and Healthy Aging. Springer, Dordrecht. https://doi.org/10.1007/978-1-4020-6869-0_2
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DOI: https://doi.org/10.1007/978-1-4020-6869-0_2
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