Effects Of Chitooligosaccharides On Alleviating Hepatic Oxidative Damage In Weaned Piglets

This experiment was carried out to determine the effects of dietary chitooligosaccharides(COS)on growth performance,hepatic redox state,structure and functions of weaned piglets with diquat injection.Twenty-four 24-day-old Duroc ×(Landrace×Yorkshire)piglets with body weight(BW)7.34±0.09 kg were randomly distributed into two groups with twelve replicates per group and one pig per replicate.Piglets were fed basal diet and basal diet + 50 mg/kg COS,respectively.Digestive trial was carried out from 18 to 21 d.On d 22,half of piglets in each group were challenged with diquat(10 mg/kgBW),the others were injected with the same volume of sterilized physiological saline.The trial lasted for 28 d.Blood were sampled on day 22(prio-diquat injection)and 29.Piglets in all groups were killed.The results showed that:(1)No significant effect of 50 mg/kg COS on the ADFI and ADG of weaned piglets before injection with diquat was observed(P>0.05),but F/G was tended to reduce(P=0.09).After diquat challenge,ADG and ADFI significantly reduced and F/G significantly enhanced(P<0.05).Supplementation of 50 mg/kg COS significantly inhibited the reduction of ADG of piglets after diquat challenge.(2)50 mg/kg COS enhanced the apparent digestibilities of dry matter,organism matter,crude protein,ether extract,energy,crude ash,calcium and phosphor(P<0.05).(3)Before injected with diquat,supplementation of 50 mg/kg COS increased the plasma SOD activity and T-AOC(P<0.05).CAT activity was down-regulated by diquat challenge(P<0.01),however,dietary COS inhibited the reduction of plasma SOD and GSH-Px activities(P<0.05)and T-AOC(P=0.07)in diquat injection group.In addition,there was no significant effect of COS on the content of plasma MDA(P>0.05).(4)Diquat injection significantly reduced the hepatic activities of SOD and GSH-Px(P<0.05),enhanced the contents of 8-OHdG and PCO(P<0.01).50 mg/kg COS enhanced the hepatic activities of SOD,CAT and T-AOC(P<0.05),alleviated MDA(P<0.05),8-OHdG and PCO in the concentration.(5)There were no significant differences in the plasma activities of ALT and AST,and the hepatic mRNA expression of Bax and Bcl-2 after diquat challenge(P>0.05).However,the mRNA expression of IL-1β and TNF-α was up-regulated,the mRNA expression of IL-10 was down-regulated in liver(P<0.05)after diquat challenge.At the same time,oxidative stress enhanced the hepatic mRNA aboundances of ER-stress related molecular chaperone as GRP78,ATF6 and PDIA4(P<0.05).Supplemented COS reduced the activity of AST as well as the mRNA expression of IL-1β IL-6 and IL-8.,enhanced the mRNA expression of IL-10(P<0.05)under diquat injection.Furthermore.COS alleviated the mRNA expression of GRP78,suppressed the up-regulation of CHOP,XBP-1 and PDIA4 mRNA and the down-regulation of Ire-1 caused by oxidative stress(P<0.05).(6)Oxidative stress induced by diquat significantly increased the hepatic glycogen content(P<0.01),reduced the hepatic mRNA expression of GLUT2 and PEPCK(P<0.1).COS enhanced the mRNA expressions of GLUT2 and PEPCK(P<0.05),and tended to enhance the mRNA expression of PGC-1 with the challenge of diquat(P=0.06).(7)There was no significant difference in the content of hepatic crude fat with the challenge of diquat(P>0.05).However,diquat injection tended to enhance the FAS mRNA expression,and suppresse the up-regulation of CPT-1(P=0.09).Adding COS tended to suppress the up-regulation of SCD,ACC,FAS mRNA expressions by diquat challenge(P<0.1).In conclusion,diquat injection induced oxidative stress,caused the hepatic oxidative damage and impaired the growth performance of weaned piglets.At the normal condition,adding 50 mg/kg COS significantly improved nutrients digestibilities,decreased F/G and enhanced the antioxidative abilities of piglets.When piglets were challenged with diquat,supplementation of 50 mg/kg COS significantly enhanced T-AOC and the abilities of SOD and GSH-Px,alleviated the content of hepatic MDA,8-OhdG and PCO to improve the antioxidative abilities in plasma and liver,alleviated the hepatic protein,lipid and DNA oxidative damages,decreased the inflammation response,and protected cell integrity through the resistance of mitochondrial and ER apoptosis pathway.Furthermore,COS has influence on hepatic gluconeogenesis,fatty acid synthesis and(3-oxidation to relieve the disorder of hepatic glucose and lipid metabolism.