Leptin and cholecystokinin in Schizothorax prenanti: molecular cloning, tissue expression, and mRNA expression responses to periprandial changes and fasting.

In the present study, full-length cDNA sequences of leptin and cholecystokinin (CCK) were cloned from Schizothorax prenanti (S. prenanti), and applied real-time quantitative PCR to characterize the tissue distribution, and appetite regulatory effects of leptin and CCK in S. prenanti. The S. prenanti leptin and CCK full-length cDNA sequences were 1121 bp and 776 bp in length, encoding the peptide of 171 and 123 amino acid residues, respectively. Tissue distribution analysis showed that leptin mRNA was mainly expressed in the liver of S. prenanti. CCK was widely expressed, with the highest levels of expression in the hypothalamus, myelencephalon, telencephalon and foregut of S. prenanti. The CCK mRNA expression was highly elevated after feeding, whereas the leptin mRNA expression was not affected by single meal. These results suggested that CCK is a postprandial satiety signal in S. prenanti, but leptin might not be. In present study, leptin and CCK gene expression were both decreased after fasting and increased after refeeding, which suggested leptin and CCK might be involved in regulation of appetite in S. prenanti. This study provides an essential groundwork to further elucidate the appetite regulatory systems of leptin and CCK in S. prenanti as well as in other teleosts.