Molecular characterization of ghrelin and gastrin-releasing peptide in Atlantic cod (Gadus morhua): Cloning, localization, developmental profile and role in food intake regulation

Full-length complementary deoxyribonucleic acid as well as genomic sequences encoding for two gastrointestinal appetite-related peptides, ghrelin and for gastrin-releasing peptide (GRP) were cloned from Atlantic cod (Gadus morhua) stomach using reverse transcription and rapid amplification of complementary deoxyribonucleic acid ends. Semi-quantitative reverse transcriptase polymerase chain reaction shows that both ghrelin and GRP are widely distributed in several peripheral tissues and throughout cod brain, although expression levels are very low, During development, ghrelin was detected at the cleavage stage, with low expression levels persisting until the first-feeding stage, while GRP was detected at the blastula stage, showing increased expression from the pre-hatching stage on. Juvenile cod fed medium rations displayed periprandial changes in gut ghrelin, but not GRP, expression, with higher expression levels at meal time compared to 2 h before feeding time. Ghrelin gut mRNA expression was not affected by rations, whereas GRP gut mRNA expression was higher in fish fed high rations as compared to fish fed low rations. Neither ghrelin nor GRP gut mRNA expressions were affected by 30 days starvation or 5 days re-feeding. (C) 2008 Elsevier Inc. All rights reserved.