The Effect Of LPS On Energy Metabolism In The Skeletal Muscle Of Pig

This study was aimed to investigate the effect of LPS treatment on muscle energy metabolism and growth in pigs.Understanding these underlying mechanisms may provide new therapeutic strategies for treating metabolic diseases induced by LPS in muscle.1 The effect of LPS injection on energy metabolism in pig LD muscle.We employed 12 growing piglets(Large White x Landrace x Duroc)with an average body weight of 12 ± 0.5 kg,and randomly assigned into a control group and a LPS-treated group.The control group animals were each injected with 2 mL of saline,and the treatment group animals were injected with 2 mL of LPS at 15 ?g/kg body weight.After 6h treatment,blood sample were collected through the jugular vein,the serum were stored at-80? until analysis.Longissimus dorsi(LD)tissue was quickly collected after slaughter and immediately frozen in liquid nitrogen;it was then stored at-80? until RNA isolation.We detected the level of serum glucose and lactic acid.Though serum glucose content showed no significant difference,serum lactic acid content significantly increased compared with the control group(P<0.05)at 6 h after the LPS injection.The glycolysis status and mitochondrial function in the LD muscle of pigs were analyzed,and endoplasm reticulum(ER)metabolism was also investigated.The results showed that serum lactate content and NADH content in LD muscle increased compared with the control group(P<0.05).Most glycolysis-related gene expression,as well as HK(hexokinase),PK(pyruvate kinase)and LDH(lactic dehydrogenase)activity,in LD muscle was significantly higher compared with the control group(P<0.05).Mitochondrial complexes I and IV significantly increased(P<0.05),while mitochondrial ATP concentration markedly decreased(P<0.05).Significantly increased calcium content in the mitochondria was observed(P<0.05),and ER stress was detected in the present study.The results showed that LPS treatment markedly changes glucose metabolism and mitochondrial function in the LD muscle of pigs,which is possibly mediated by ER-mitochondrial calcium communication.The results provide new therapeutic strategies for metabolic diseases induced by LPS in muscle.2 The effect of LPS injection on growth related genes expression in pig LD muscle.We employed 12 ternary piglets(Large White x Landrace x Duroc)with an average body weight of 12 ± 0.5 kg,and randomly assigned into a control group and a LPS-treated group.After 6h treatment,LD muscle tissue was immediately frozen in liquid nitrogen after slaughter and stored at-80? until RNA isolation.The results show that LPS treatment significantl decreased the expression of IGF-1(P<0.05)without any effect on IGF-1R and mTOR.Autophay related gene LC3 significantly increased(P<0.05),ULK-1 and ATG6 have a increase tendency(P = 0.063)without any effect on ATG7 and ATG9.The key genes of ubiquitin lysosome system including Foxo1,atrogin-1 and MuRF-1 significantly increased(P<0.05).The gene and protein level of MSTN has no significant difference after LPS treatment.We also detected the expression of MRFs genes,the results show that MyoD and MyoG significantly increasd(P<0.05),however without any effect on Myf5 and Myf6(P<0.05).The LPS treatment also didn't change the protein level of MyoG?Myf5 and Myf6.These results show that LPS treatment significantly suppressed the expression of muscle growth and differentiation related gene such as IGF-1,MyoG and MyoD;and significantly increased the expression of protein degradation(including autophagy and ubiquitin-proteasome system)related genes.