Regulatory Effect Of Asparagine On Intestinal Injury In Piglets After Lipopolysaccharide Challenge

Two experiments were conducted to investigate the effects of asparagine (ASN)supplementation on intestinal structure and function of weanling piglets afterlipopolysaccharide (LPS) challenge and its mechanisms.1. Experiment1was conducted to explore the mechanism(s) which ASNexerted its protective role on intestinal damage from the perspective of energymetabolism. Pigs （average weight was7.37±0.04kg） were allotted to fourtreatments including:①nonchallenged control (NONC);②challenged control(CHAC);③0.5%ASN (0.5%ASN);④1.0%ASN (1.0%ASN). On d24, pigs in theCHAC,0.5%ASN and1.0%ASN groups were injected intraperitoneally with LPS,whereas pigs in the NONC group were injected with an equivalent amount of sterilesaline. The pigs were slaughtered after24h LPS challenge to collect intestinalsamples for analysis. The results showed that:(1) ASN can alleviate the change ofintestinal structure induced by LPS (P<0.05).(2)0.5%ASN or1.0%ASN canalleviate the decrease of ileal RNA/DNA and Protein/DNA induced by LPS,increase jejunal RNA/DNA and Protein/DNA (P<0.05).(3)0.5%and1.0%ASN canalleviate the decrease of jejunal maltase activity and increase the activity of jejunallactase and ileal sucrase (P<0.05).(4)0.5%ASN or1.0%ASN can alleviate thedecrease of ileal ATP content and EC and the increase of ileal AMP/ATP,0.5%ASNcan increase jejunal ATP content and EC, decrease jejunal AMP content andAMP/ATP (P<0.05).(5)0.5%ASN and1.0%ASN can alleviate the decrease ofjejunal and ileal citrate synthase、Isocitrate dehydrogenase and alpha oxoglutaratedehydrogenase complex activities (P<0.05).(6)0.5%ASN or1.0%ASN canalleviate the increase of mRNA expression of jejunal PGC-1α and ileal AMPKα1,AMPKα2and PGC-1α (P<0.05), decrease mRNA expression of jejunal AMPKα1and Sirt1(P<0.05). ASN can alleviate the increase of ileal pAMPK/tAMPK (P<0.05). These results show that ASN may protect intestine structure and functiona by increasing energy supply.2. Experiment2was conducted to explore the mechanism(s) which ASNexerted its protective role on intestinal damage from the perspective ofinflammatory response. Pigs（average weight was8.07±0.75kg）were allotted tofour treatments including:①nonchallenged control (NONC);②challenged control(CHAC);③0.5%ASN (0.5%ASN);④1.0%ASN (1.0%ASN). On d21, pigs inthe CHAC,0.5%ASN and1.0%ASN groups were injected intraperitoneally withLPS, whereas pigs in the NONC group were injected with an equivalent amount ofsterile saline. The pigs were slaughtered after4h LPS challenge to collectintestinal samples for analysis. The results showed that；(1)0.5%and1.0%ASNcan alleviate the change of intestinal structure induced by LPS (P<0.05).(2)0.5%ASN and1.0%ASN can alleviate the decrease of protein expression of jejunalOccludin and Claudin-1, increase jejunal DAO activity,1.0%ASN can increaseprotein expression of ileal Claudin-1(P<0.05).(3) ASN can decrease proteinexpression of ileal Caspase-3(P<0.05).(4)0.5%ASN and1.0%ASN can alleviatethe increase of mRNA expression of jejunal MyD88, RIPK2and NF-κB p65andileal TLR4, TRAF6, NOD2, RIPK2and NF-κB p65(P<0.05).0.5%ASN candecrease mRNA expression of ileal MyD88and NOD1,1.0%ASN can alleviate theincrease of mRNA expression of jejunal TRAF6and NOD2, decrease mRNAexpression of ileal MyD88, IRAK1and NOD1(P<0.05). These results show thatASN may protect intestine structure and function a by inhibiting the inflammatoryresponses.