Regulation of glucose uptake in fast and slow skeletal muscles with fasting and refeeding

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 (Acipenser baerii), this study first cloned nmu cDNA sequence that encoded 154 amino acids including NMU-25 peptide. Besides, the results showed that nmu 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 nmu mRNA expression was significantly decreased at 1 and 3 h after feeding in different brain regions. Similarly, after feeding, the expression of nmu significantly decreased in peripheral tissues. Moreover, nmu 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 i.c.v. and i.p. injection of NMU and chronic i.p. injection of NMU significantly reduced the food intake in a dose-dependent mode. In addition, the expressions of several critical appetite factors (nmu, aplein, cart, cck, ghrelin, npy, nucb2, pyy and ucn3) 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.

Research on quality changes of grass carp (Ctenopharyngodon idellus) during short-term starvation

This study was aimed at to investigate the quality changes of grass carp during short-term starvation. The pH, lactic acid, free amino acid, and adenosine triphosphate-related compounds of dorsal meat, belly meat and red meat in grass carp were measured during starvation for 6 days, and the quality of grass carp was evaluated by K value, equivalent umami concentration (EUC), taste activity value (TAV), and electronic tongue. The pH of three parts meat reached the maximum value on the fourth day, which was closely related to the lactic acid content. Concurrently, the contents of fresh sweet amino acids were higher on the fourth day in all parts. The K values in dorsal meat and belly meat were below 10% during starvation. Considering the overall results of electronic tongue, EUC, and TAV analysis, it is suggested that grass carp should be marketed and eaten with a starvation period of 2-4 days for best taste and quality.