Effects Of Long-term Intake Of Raw Potato Starch Diet On Gene Expression And Metabolism In The Colon And Liver Of Pigs

Raw potato starch,known as one kind of resistant starch,is a complex polysaccharide that resists digestion and absorption in both human and animal small intestines,and enters the large intestine for bacterial fermentation.The beneficial effects of RS include decreasing in postprandial glycemic and insulinemic responses,increasing satiety,and reducing adipose deposition.The mechanism of benefit of RS in most studies was related to the modulation of the microbiota,short-chain fatty acids(SCFAs)profile,and secretion of satiety-stimulating hormones in the intestine.However,information concerning the effects of RS on animals at an extraintestinal level is still relatively limited.The present study was to investigate the mechanism of resistant starch in the colon and extraintestinal level.Thestudy would provided new insights into our understanding of the impacts of long-term intake of PRS on body metabolisms,and so provides benefits to animal nutrition and health.The paper was divided into four parts:1 Effects of long-term intake of raw potato starch diet on the microbial communities in the colon of pigsThe aim of this study was to investigate the effects of long-term intake of RPS on microbial composition in the colon of pigs.Thirtysix Duroc × Landrace × Large White growing barrows(70 d of age)were randomly allocated to either the com starch(CS)group or the raw potato starch(RPS)group with a randomized complete block design;each group consisted of 6 replicates(pens),with 3 pigs per pen.Pigs in the CS group were offered a com-soybean-based diet,whereas pigs in the RPS group were put on a diet in which 230(growing)or 280 g/kg(finishing)purified CS was replaced with purified RPS during a 100-d trial.Real-time PCR assay showed that RPS significantly decreased the number of total bacteria in the colonic digesta.MiSeq sequencing of the V3-V4 region of the 16S rRNA genes showed that RPS significantly decreased the the richness estimators(ACE and Chao)of colonic microbiota and increased the abundances of Turicibacter,Ruminococcus,Blautia,Coprococcus,Marvinbryantia,and Lachnospiraceae incertaesedis,and decreased the abundances of Clostridium,S24-7,RC9 gut group,Parabacteroides,Phascolarctobacterium,Oscillospira,Oscillibacter,and Mogibacterium on the genera level.In conclusion,long term intake of raw potato starch diet markedly strengthened beneficial bacteria and suppressed harmful bacteria in the colon of pigs.2 Effects of long-term intake of raw potato starch diet on the genes expression profiles in the colon of pigsThe aim of this study was to investigate the effects of long-term intake of RPS on genes expression profiles in the colon of pigs.Our results showed that 549 differentially expressed genes were detected and functional annotated in the colon in RPS group.Analysis of the colonic transcriptome profiles revealed that the RPS diet changed the colonic expression profile of the host genes mainly involved in immune response pathways.RPS significantly increased proinflammartory cytokine IL-1? gene expression and suppressed genes,including LIPA,GALANS,CTSZ,CTSB and CTSD,which involved in lysosome.In general,present results indicate that long-term intake of raw potato starch diet may may result in some negative roles in gut health.3 Effects of long-term intake of raw potato starch diet on the genes expression profiles in the liver of pigsAs the metabolic center of the body,liver has been postulated to be responsible for the beneficial role of RS in the body.And information concerning the effects of RS on animals at an extraintestinal level is still relatively limited.Then we investigate the effects of long-term intake of RPS on genes expression profiles in the liver of pigs.The gene expression profiles showed that 237 differentially expressed transcripts were identified and annotated between the CS and RPS groups at the particular cut-off criteria(fold change ?1.5 or<0.67,P<0.05).Transcriptomic results showed that the expression of CD36,carnitine palmitoyltransferase IB(CPT1B)and medium-chain acyl-CoA dehydrogenase(ACADM)was down-regulated,while 1-acylglycerol-3-phosphate O-acyltransferase 4(AGPAT4),glycerol-3-phosphate acyltransferase(GPAT)and fatty acid binding protein 1(FABP1)were up-regulated by the RPS diet,indicating a decrease in fatty acid intake and synthesis,and an increase in fatty acid oxidation and glycerophospholipid synthesis at the molecular level in the liver of RPS group.4 Effects of long-term intake of raw potato starch diet on the metabolomic profiles in the liver of pigsMetabolite profiling alterations in the metabolome can provide an insight into the end points of metabolic fluxes in cells,tissues,or the whole body,which significantly contributes to our understanding of the mechanism of RPS diet.Metabolomic analysis by gas chromatography-mass spectrometry(GC-MS)showed that compared with the CS diet,the RPS diet significantly decreased cholesterol and palmitic acid,as well as increasing 3-Hydroxybutyric acid,which indicates the reduction of adipose weight and fatty acid biosynthesis,and the elevation of fatty acid ?-oxidation.In addition,2-ketoglutaric acid and glucose-6-phosphate were significantly increased,although pPnruvic acid was decreased in the RPS group,indicating the up-regulated capacity of glucose phosphorylation,glycolysis and TCA.The results demonstrate that the long-term consumption of RPS can modulate hepatic lipid metabolism by decreasing fatty acid synthesis,as well as increasing lipid oxidation,may be benefit for liver health.