Neuromedin U regulates food intake of Siberian sturgeon through the modulation of central and peripheral appetite factors.

Neuromedin U (NMU) has a critical function on the regulation of food intake in mammals, while the information is little in teleost. To investigate the function of NMU on appetite regulation of Siberian sturgeon (), this study first cloned cDNA sequence that encoded 154 amino acids including NMU-25 peptide. Besides, the results showed that mRNA was widely distributed in various tissues especially in the hypothalamus and telencephalon. The results of nutritional status (pre-feeding and post-feeding, fasting and re-feeding) experiments showed that mRNA expression was significantly decreased at 1 and 3 h after feeding in different brain regions. Similarly, after feeding, the expression of significantly decreased in peripheral tissues. Moreover, expression in the hypothalamus was significantly increased after fasting 1 d, but decreased after fasting 17 d, which was significantly reversed after re-feeding. However, other brain regions like telencephalon and peripheral tissues like oesophagus, intestinum valvula and liver have different change patterns. Further study showed that acute and injection of NMU and chronic injection of NMU significantly reduced the food intake in a dose-dependent mode. In addition, the expressions of several critical appetite factors (, , , , , , , and ) were significantly affected by acute NMU-25 administration in the hypothalamus, intestinum valvula and liver. These results indicate that NMU-25 has the anorexigenic function on food intake by affecting different appetite factors in Siberian sturgeon, which provides a foundation for further exploring the appetite regulation networks in fish.