title: Response of the somatotropic axis to alterations in feed intake of channel catfish (Ictaluruspunctatus).
abstract: To better understand the effects of reduced feeding frequency on the GH-IGF-I axis, channel catfish (Ictaluruspunctatus), were either fed (Fed control, commercial diet fed daily), fed every other day (FEOD, commercial diet fed every other day), or not fed (Unfed, no feed). Pituitary GH mRNA increased whereas hepatic growth hormone receptor (GHR), IGF-I mRNA, and plasma IGF-I decreased in the FEOD and Unfed fish (P<0.05). In another study, fish were either continually fed (Fed) or fasted and then re-fed (Restricted) to examine the physiological regulation of somatostatin-14 (SS-14) and SS-22 mRNA. Fasting increased (P<0.05) levels of SS-14 mRNA in the hypothalamus and pancreatic islets (Brockmann bodies) at d 30 while re-feeding decreased SS-14 mRNA to control values in all tissues examined by d 45. Fasting had no effect on levels of SS-22 mRNA in the pancreatic islets whereas SS-22 mRNA was not detected in the stomach or hypothalamus. The results demonstrate that feeding every other day has similar negative impacts on components of the GH-IGF-I axis as fasting. The observed increase in SS-14 mRNA in the hypothalamus and pancreatic islets suggests a role for SS-14 in modulating the GH-IGF-I axis in channel catfish.
authors.affiliation: USDA/ARS Catfish Genetics Research Unit, Thad Cochran National Warmwater Aquaculture Center, PO Box 38, Stoneville, MS 38776, USA. brian.peterson@ars.usda.gov
authors.forename: B C
authors.initials: BC
authors.lastname: Peterson
authors.forename: A L
authors.initials: AL
authors.lastname: Bilodeau-Bourgeois
authors.forename: B C
authors.initials: BC
authors.lastname: Small
mesh_terms: D000821:Animal Feed; D000818:Animals; D001483:Base Sequence; D017931:DNA Primers; D013006:Growth Hormone / Q000235:genetics / Q000502:physiology*; D017228:Hepatocyte Growth Factor / Q000235:genetics; D007031:Hypothalamus / Q000378:metabolism; D007059:Ictaluridae / Q000502:physiology*; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000502:physiology*; D007515:Islets of Langerhans / Q000378:metabolism; D010902:Pituitary Gland / Q000378:metabolism; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics; D013004:Somatostatin / Q000235:genetics
chemical_list: D017931:DNA Primers; D012333:RNA, Messenger; D013004:Somatostatin; D017228:Hepatocyte Growth Factor; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone