A dose of experimental hormesis: When mild stress protects and improves animal performance

• Published in: Comparative biochemistry and physiology. Part A, Molecular & integrative physiology Molecular & integrative physiology, 2020-04, Vol.242, p.110658-110658, Article 110658
• Main Authors: Berry, Raymond, López-Martínez, Giancarlo
• Format: Article
• Language: English
• Subjects: Animals; Antioxidants; Antioxidants - metabolism; Dose response; Hormesis; Life history; Longevity; Oxidative Stress; POS hypothesis; Reproduction; Trade-offs
• ISSN: 1095-6433; 1531-4332; 1531-4332
• DOI: 10.1016/j.cbpa.2020.110658

The adaptive response characterized by a biphasic curve is known as hormesis. In a hormesis framework, exposure to low doses leads to protective and beneficial responses while exposures to high doses are damaging and detrimental. Comparative physiologists have studied hormesis for over a century, but our understanding of hormesis is fragmented due to rifts in consensus and taxonomic-specific terminology. Hormesis has been and is currently known by multiple names; preconditioning, conditioning, pretreatment, cross tolerance, adaptive homeostasis, and rapid stress hardening (mostly low temperature: rapid cold hardening). These are the most common names used to describe adaptive stress responses in animals. These responses are mechanistically similar, while having stress-specific responses, but they all can fall under the umbrella of hormesis. Here we review how hormesis studies have revealed animal performance benefits in response to changes in oxygen, temperature, ionizing radiation, heavy metals, pesticides, dehydration, gravity, and crowding. And how almost universally, hormetic responses are characterized by increases in performance that include either increases in reproduction, longevity, or both. And while the field can benefit from additional mechanistic work, we know that many of these responses are rooted in increases of antioxidants and oxidative stress protective mechanisms; including heat shock proteins. There is a clear, yet not fully elucidated, overlap between hormesis and the preparation for oxidative stress theory; which predicts part of the responses associated with hormesis. We discuss this, and the need for additional work into animal hormetic effects particularly focusing on the cost of hormesis. [Display omitted] •Hormesis is an adaptive response also known as preconditioning, pretreatment, cross tolerance, and rapid stress hardening.•Most animal hormesis work has investigated changes in oxygen or temperature which are connected to overwintering strategies.•The mechanism of hormesis involves antioxidant enzymes and oxidative stress protection and aligns with the POS hypothesis.•Little is known about the cost of hormesis, but decreased reproduction output has been implicated multiple times.