title: Neuropeptide regulation of feeding in catfish, Ictalurus punctatus: a role for glucagon-like peptide-1 (GLP-1)?
abstract: Glucagon-like peptide 1 is a compound known to cause reduced food intake in mammals, though its action on feed intake in fish is unknown. The clear differences in the effects of GLP-1 on mammalian and teleostean glucose homeostasis suggest that we cannot assume a similar action of GLP-1 on feeding in mammals and fish. In this study the effects and specificity of centrally administered GLP-1 on feed intake were examined. It was demonstrated that intracerebroventricular (ICV) injection of glucagon-like peptide 1 (GLP-1) in the channel catfish (Ictalurus punctatus) is a potent inhibitor of feed intake with a dose of 0.25 ng g(-1) body wt. reducing feed intake by 50%. The weak response to intraperitoneal (i.p.) and intravenous (i.v.) injection treatments with GLP-1 suggests the major effects on feed intake are centrally mediated. GLP-1 action on feed intake was not antagonized by ICV injection of exendin(9-39). Immunoneutralization of GLP-1 by ICV injection of antisalmon GLP-1 antisera did not affect feed intake over 48 h, while ICV injection of GLP-1 at a dose of 30 ng g(-1) body wt. reduced feed intake for over 20 h. Additionally, there is some evidence that GLP-1 caused gastric evacuation. We conclude that GLP-1 is a potent inhibitor of feeding in fish, but its involvement in feed intake regulation under physiological conditions remains to be clarified.
authors.affiliation: USDA, ARS, Catfish Genetics Research Unit, Thad Cochran National Warmwater Aquaculture Center, 38776, Stoneville, MS, USA. jsilvers@ars.usda.gov
authors.forename: J T
authors.initials: JT
authors.lastname: Silverstein
authors.forename: V M
authors.initials: VM
authors.lastname: Bondareva
authors.forename: J B
authors.initials: JB
authors.lastname: Leonard
authors.forename: E M
authors.initials: EM
authors.lastname: Plisetskaya
mesh_terms: D000818:Animals; D004435:Eating / Q000187:drug effects*; D005247:Feeding Behavior / Q000187:drug effects*; D005934:Glucagon / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D052216:Glucagon-Like Peptide 1; D007059:Ictaluridae / Q000502:physiology*; D007106:Immune Sera / Q000494:pharmacology; D009479:Neuropeptides / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D010446:Peptide Fragments / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D011498:Protein Precursors / Q000037:antagonists & inhibitors / Q000494:pharmacology*
chemical_list: D007106:Immune Sera; D009479:Neuropeptides; D010446:Peptide Fragments; D011498:Protein Precursors; C083773:exendin (9-39); D052216:Glucagon-Like Peptide 1; D005934:Glucagon