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United States Department of Agriculture

Agricultural Research Service

Research Project: CATFISH GENETICS, BREEDING, AND PHYSIOLOGY

Location: Warmwater Aquaculture Research Unit

Title: Response of the Somatotropic Axis to Alterations in Feed Intake of Channel Catfish (Ictalurus punctatus)

Authors
item Peterson, Brian
item Small, Brian
item Bourgeois, Lanie

Submitted to: Comparative Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 17, 2009
Publication Date: May 3, 2009
Citation: Peterson, B.C., Small, B.C., Bourgeois, A.L. 2009. Response of the Somatotropic Axis to Alterations in Feed Intake of Channel Catfish (Ictalurus punctatus). Comparative Biochemistry and Physiology. 153: 457-463.

Interpretive Summary: The growth hormone-insulin like growth factor-I (GH-IGF-I) axis is the primary regulator of growth in channel catfish. To better understand the effects of reduced feeding frequency on the GH-IGF-I axis, channel catfish, (Ictalurus punctatus), were either fed (FED), fed every other day (FEOD), or not fed (Unfed). Pituitary GH mRNA increased whereas hepatic growth hormone receptor (GHR), IGF-I mRNA, and plasma IGF-I decreased in FEOD and Unfed fish. In another study, fish were either continually fed (Fed) or fasted and then re-fed (Restricted) to examine regulation of two genes that negatively regulate growth, somatostatin-14 (SS-14) and SS-22 mRNA. Fasting increased SS-14 mRNA in the hypothalamus and pancreatic islets (Brockmann bodies) while re-feeding restored SS-14 mRNA in all tissues examined. Fasting had no effect on levels of SS-22 mRNA in the pancreatic islets whereas SS-22 mRNA was not detected in the gut 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 regulating growth in channel catfish.

Technical Abstract: To better understand the effects of reduced feeding frequency on the GH-IGF-I axis, channel catfish, (Ictalurus punctatus), 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) while re-feeding restored SS-14 mRNA in all tissues examined. Fasting had no effect on levels of SS-22 mRNA in the pancreatic islets whereas SS-22 mRNA was not detected in the gut 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.

Last Modified: 8/22/2014
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