title: Plasma IGF-1 is negatively correlated with body mass in a comparison of 36 mammalian species.
abstract: In mammals, insulin-like growth factor-1 (IGF-1) is positively correlated with adult body mass, in comparisons made within a given species. In mice, IGF-1 deficiency is associated with dwarfism, whereas IGF-1 overproduction in transgenic animals causes gigantism. Surprisingly, the opposite is true in an inter-species context. We collected published plasma total IGF-1 data for adults of 36 mammalian species and analyzed it with respect to body mass. In contrast to the intra-species observation, this analysis revealed a significant negative correlation of plasma IGF-1 with body mass. Interestingly, IGF-1 is negatively correlated with longevity, and suppression of IGF-1 signalling in worms, flies and mice increases lifespan. Smaller mouse strains, for example, tend to have lower plasma IGF-1 levels and to be longer-lived. However, when plasma total IGF-1 was analyzed relative to the maximum lifespans of the 36 species examined here, there was no statistically significant correlation. Low plasma IGF-1 levels in larger mammalian species may be physiologically significant, considering the roles of this hormone in metabolism, tissue regeneration, and cancer incidence.
authors.affiliation: Department of Biological Sciences, Brock University, 500 Glentidge Ave., St. Catharines, ON, Canada L2S 3A1. jstuart@brocku.ca
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Stuart
authors.forename: Melissa M
authors.initials: MM
authors.lastname: Page
mesh_terms: D000818:Animals; D001823:Body Composition; D015992:Body Mass Index; D001835:Body Weight; D005260:Female; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000096:biosynthesis* / Q000378:metabolism*; D008136:Longevity; D008297:Male; D051379:Mice; D010802:Phylogeny; D012038:Regeneration; D013045:Species Specificity; D013997:Time Factors
chemical_list: D007334:Insulin-Like Growth Factor I