title: The role of insulin-like growth factor-1 (IGF-1) in growth and reproduction in female brown house snakes (Lamprophis fuliginosus).
abstract: Insulin-like growth factor-1 (IGF-1) is a peptide hormone critically involved in the regulation of key life-history traits such as growth and reproduction. Its structure and function are well-characterized among diverse mammal, fish, and bird species; however, little is known regarding the activities of IGF-1 in non-avian reptiles, particularly snakes and lizards. Nevertheless, several unique characteristics of reptiles, such as high metabolic flexibility and remarkable diversity in life-history strategy, suggest that they are of great interest in the study of endocrinological mechanisms underlying the regulation and evolution of life-history traits. Here we test for a relationship between IGF-1 and individual feeding rate, growth rate and reproductive stage in lab-reared female offspring of wild-caught oviparous house snakes, Lamprophis fuliginosus. We confirm a positive correlation between IGF-1 and both feeding and growth rates in sexually immature snakes, similar to that reported in other taxa. We also show a family effect on IGF-1, suggesting that IGF-1 levels may be heritable in these snakes, and serve as an important target of selection to produce divergent life-history strategies. Furthermore, we provide evidence that suggests that IGF-1 may peak rapidly after first mating, and subsequently decline prior to egg-laying, a phenomenon not previously reported in other taxa. These findings suggest that further comparative study of IGF-1 in snakes may reveal both the extent to which IGF-1 function is conserved across major taxonomic groups, as well as novel and intriguing roles for IGF-1 in the regulation of reproductive activities.
authors.affiliation: Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames, IA, USA. asparkma@gmail.com
authors.forename: A M
authors.initials: AM
authors.lastname: Sparkman
authors.forename: D
authors.initials: D
authors.lastname: Byars
authors.forename: N B
authors.initials: NB
authors.lastname: Ford
authors.forename: A M
authors.initials: AM
authors.lastname: Bronikowski
mesh_terms: D000818:Animals; D017812:Colubridae / Q000254:growth & development / Q000378:metabolism* / Q000502:physiology*; D005260:Female; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D011863:Radioimmunoassay; D012098:Reproduction / Q000502:physiology*
chemical_list: D007334:Insulin-Like Growth Factor I