Stimulating hair growth via hormesis: Experimental foundations and clinical implications.

Numerous agents (approximately 90) are shown to stimulate hair growth in cellular and animal models in a hormetic-like biphasic dose response manner. These hormetic dose responses occur within the framework of direct stimulatory responses as well as in preconditioning experimental protocols. These findings have important implications for experimental and clinical investigations with respect to study design strategies, dose selection and dose spacing along with sample size and statistical power issues. These findings further reflect the general occurrence of hormetic dose responses within the biological and biomedical literature that consistently appear to be independent of biological model, level of biological organization (i.e., cell, organ, and organism), endpoint, inducing agent, potency of the inducing agent, and mechanism.