title: The effects of insulin/IGF-I on glucose and leucine metabolism in the redclaw crayfish (Cherax quadricarinatus).
abstract: In recent years, invertebrate peptides have been identified which share substantial homologies with vertebrate insulin and insulin-like growth factors (IGFs), indicating a high degree of conservation of insulin/IGF systems through animal evolution. In a previous study, we provided evidence for the presence of IGF-I-like peptides in the redclaw (Cherax quadricarinatus), a species of freshwater crayfish endemic to northern Australia river systems which has attained support as a culture species. The general aim of the current study was to elucidate the functional significance of IGF-I-like peptides in this species by examining the effects of mammalian IGF-I on glucose and leucine metabolism. Juvenile redclaw were injected with a single dose of purified human insulin, recombinant human (rh) IGF-I, or Des-1-3-IGF-I. Glucose levels in redclaw tissues were then determined over an 8-hr period using enzymatic approaches. It was shown that injection of rhIGF-I induced an acute increase in free glucose content in hepatopancreas while Des-1-3-IGF-I and insulin raised free glucose levels in abdominal muscle. Radiolabel tracer approaches also demonstrated that injection of rhIGF-I increased glycogen synthesis in abdominal muscle and elevated the incorporation of leucine into protein in both abdominal muscle and hepatopancreas. Taken together, the findings of this study suggest that IGF-I-like peptides are biologically active in this species and may be of significance to metabolic and growth-related processes.
authors.affiliation: Centre for Molecular Biotechnology, School of Life Science, Queensland University of Technology, Brisbane, Australia. n.richardson@qut.edu.au
authors.forename: N A
authors.initials: NA
authors.lastname: Richardson
authors.forename: A J
authors.initials: AJ
authors.lastname: Anderson
authors.forename: V R
authors.initials: VR
authors.lastname: Sara
mesh_terms: D000818:Animals; D003400:Astacoidea / Q000187:drug effects* / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D007328:Insulin / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D007700:Kinetics; D007930:Leucine / Q000378:metabolism*; D008099:Liver / Q000378:metabolism; D009132:Muscles / Q000378:metabolism; D010179:Pancreas / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology
chemical_list: D007328:Insulin; D011994:Recombinant Proteins; D007334:Insulin-Like Growth Factor I; D007930:Leucine; D005947:Glucose