Ya-fish (Schizothorax prenanti) spexin: identification, tissue distribution and mRNA expression responses to periprandial and fasting.

Spexin (SPX) is a novel peptide which was known for its role in physiological homeostasis. A recent study has confirmed that SPX plays an important role in the feeding regulation. However, the reports about SPX are very limited. In the present study, we characterized the structure, distribution and mRNA expression responses to feeding status of SPX in Ya-fish (Schizothorax prenanti). The full-length cDNA of Ya-fish SPX was 1330 base pairs (bp), which encoded 106 amino acid residues. These residues contained a 31-amino acid signal peptide region and a 14-amino acid mature peptide. The sequence alignment demonstrated that the Ya-fish SPX showed high conservation with other species. Our data revealed that SPX was widely expressed in all test tissues. The highest expression of SPX mRNA was observed in Ya-fish forebrain. Compared with the Ya-fish SPX mRNA expression in the forebrain between the preprandial and postprandial groups, the fed group was prominently increased than unfed groups after a meal, while the unfed group at 1 and 3 h substantially decreased than preprandial groups (P < 0.01). In addition, SPX mRNA expression in forebrain was significantly decreased (P < 0.01) during fasting for a week and sharply increased (P < 0.01) after refeeding on the 7th day, and then return to normal level on the 9th day. These results point toward that SPX mRNA expression is regulated by metabolic status or feeding conditions in Ya-fish.