The Regulation Of Feeding Of Neuromedin U In Siberian Sturgeon (Acipenser Baerii Brandt)

In order to study the feeding regulation of NMU in fish,we cloned the NMU,NMUR1 and NMUR2 gene sequences of Siberian sturgeon for the first time,analyzed their distribution in different tissues and their expression levels and patterns in different nutritional states,and explored the effect on feeding intake,NMUR1,NMUR2 and related appetite regulators through short-term and long-term,ip and icv injection of NMU-25.1.The length of part of the NMU cDNA of Siberian sturgeon was 540 bp,which contained mature peptide NMU-25.NMU gene was widely expressed in 22 tissues tested.Among them,the highest expression of nmu was in the telencephalon,followed by the hypothalamus.Pre-and post-feeding tests showed that compared with the fasting group,nmu decreased significantly in the hypothalamus,telencephalon,mesencephalon,cerebellum and medulla after 1h of feeding,and decreased significantly in the esophagus,ileum,duodenum and muscle after 1h and 3h of feeding.Compared with the feeding group,the nmu mRNA expression in the hypothalamus of Siberian sturgeon increased significantly in the first day,but decreased significantly in the 3,6,10,15 and 17 day,the re-feeding group was significantly higher than the fasting group on the 15 and 17 day.2.We cloned part sequences of NMUR1 and NMUR2,including 338 bp of NMUR1 and 349 bp of NMUR2.The expression of nmur1 mRNA was highest in muscle,higher in hypothalamus;the expression of nmur2 mRNA was highest in spleen and higher in hypothalamus.Pre-and post-feeding tests showed that nmur1 mRNA significantly decreased in hypothalamus,esophagus,ileum and duodenum.Compared with fasting group,nmur2 mRNA decreased significantly in hypothalamus,mesencephalon esophagus,ileum and duodenum after 1 and 3h of feeding.The results of fasting and re-feeding experiment showed that nmur1 mRNA expression in the hypothalamus of Siberian sturgeon on the first day increased significantly compared with the feeding group,decreased significantly in the fasting group in the 3,6,10,15 and 17 day,and was significantly higher in the re-feeding group in the 10,15 and 17 day than in the fasting group.Compared with the feeding group,the nmur2 mRNA expression in the hypothalamus and liver of Siberian sturgeon increased significantly in the 1,3,6,10,15 and 17 days.On the 15 day,the nmur2 mRNA expression in the re-feeding group was significantly lower than that in the fasting group.3.Short-term i.p injection of 50,100,200 ng/g BW NMU-25 reduced the 0-1 h intake of Siberian sturgeon and the cumulative intake of 1 h,3 h and 6 h;Short-term intraperitoneal injection of 100 ng/g BW NMU-25 significantly decreased the expression of apelin,pyy,npy and nmu,and significantly increased the expression of cart and ucn3 in hypothalamus,opposite effects in the stomach.NMU-25 significantly increased apelin,nmu,nucb2,cck,ghrelin and pyy,and significantly decreased cart and ucn3,nmur1 and nmur2 mRNA expression.Long-term i.p injection of NMU-25 with 50,100 and 200 ng/g BW decreased the intake and cumulative intake for 1-7 days.The expression of nmu,npy,pyy,nucb2,cart,ghrelin and nmur2 in hypothalamus was significantly increased,and nmur1 mRNA decreased significantly by continuous injection of 100ng/g BW NMU-25 for 7 days,while the expression of apelin,cart,npy,pyy,ucn3,nucb2,nmu,cck,ghrelin and nmur2 was significantly decreased in muscle.Intraventricular injection 1,10,100 pmol/g BW NMU-25 decreased 0-1 h feeding and 1,3,6 h cumulative feeding of Siberian sturgeon.I.cv injection of NMU-25 with 10 pmol/g BW decreased the expression of npy,ucn3,apelin,cart,nucb2,cck,ghrelin and nmu in hypothalamus,significantly increased the expression of nmur1 and nmur2,and significantly decreased pyy,apelin,nmur1 and nmur2,significantly increased the expression of npy,ucn3,nucb2,nmu,cart,cck and ghrelin in stomach.Conclusion: NMU,as an aorexigenic factor,can inhibit short-term and long-term feeding of Siberian sturgeon.Regulating the expression of appetite-related factors and their receptors may have opposite effects in the central and peripheral tissues,suggested that regulated by different pathways in the central and peripheral tissues.