Submitted to: Global Aquaculture Advocate
Publication Type: Trade Journal
Publication Acceptance Date: 6/16/2008
Publication Date: 7/1/2008
Citation: Kobayashi, Y., Peterson, B.C., Waldbieser, G.C. 2008. Regulators of Food Intake in Channel Catfish. Global Aquaculture Advocate July/August p. 66-67.
Interpretive Summary: We tested the hypothesis that differences in feed intake between lines of catfish with different growth rates were caused by differences in the amount of Cocaine-and Amphetamine-Regulated Transcript (CART), a neurotransmitter that inhibits feed intake. This study showed that faster-growing fish had less CART gene activity in the brain than did slower-growing fish. In another study we compared CART gene activity between fed, fasted, and fasted fish followed by 15 days of refeeding. This study showed that 30 days of fasting reduced CART gene activity, and 15 days of re-feeding restored CART gene activity to a level observed in fish that were fed daily. These results showed that catfish CART has functional properties very similar to those in other vertebrate species. Our future work will focus on whether measuring CART gene activity can be used to identify lines of catfish with improved feed efficiency.
Technical Abstract: Cocaine-and Amphetamine-Regulated Transcript (CART) is a potent hypothalamic anorectic peptide in mammals and fish. We hypothesized that increased food intake is associated with changes in expression of CART mRNA within the brain of channel catfish. Objectives were to clone the CART gene, examine tissue CART mRNA distribution, and changes in the amount of CART mRNA in relation to changes in food intake in channel catfish. Our results showed that channel catfish CART was highly similar to those of other fish species, particularly in the biologically active portion of the peptide. Expression of CART mRNA was detected in the brain and testis but not in other somatic tissues. Thirty days of fasting decreased (P<0.05) the amount of CART mRNA within the brain of channel catfish, while refeeding for 15 days restored its amount to a level similar to the fed control. In a separate 7 week feeding study, CART mRNA expression was lower in fish that consumed more food and gained more weight (P<0.05). These results suggest that CART is involved in regulation of food intake in channel catfish, similarly as it has been reported in other fish and mammals.