The guppy (Poecilia reticulata) is a useful model for analyzing age-dependent changes in metabolism, motor function,...

Aging is a major risk factor for many chronic diseases, causing a general decline in physiological function and loss of homeostasis. Recently, small teleost fish have been used as animal models of aging research because their genetic structures and organs closely resemble those of humans. Guppy (Poecilia reticulata), a small teleost fish, has a shorter lifespan than zebrafish. However, the age-dependent changes in physiology and genetics in guppies are not well understood. Here, we investigated the age-associated changes in metabolic rate, physical activity, and gene expression in guppies. Our results indicated that the resting metabolic rate and spontaneous motor activity in guppies decreased from an earlier age than those in mice. Moreover, the mRNA expression level of ppargc1a and the accumulation of lipofuscin were affected by age in the guppy livers; however, these changes were species-specific. On the other hand, in aged guppy brains, the mRNA expression changes of some genes were partly consistent with aged mammals. Although the process of senescence of the liver in guppies might vary from mammals, our findings suggest that guppy could be a useful animal model for age-related changes in physiological functions.