Effects Of Glycyrrhiza Polysaccharide On Growth Performance And Intestinal Health Of Weaned Piglets

As one of the active components of licorice,glycyrrhiza polysaccharide(GCP)has various biological activities such as antioxidant,immune regulation,anti-tumor,apoptosis,antibacterial,anti-inflammatory,and intestinal flora regulation.Previous studies have found that Glycyrrhiza polysaccharides can effectively improve the production performance of suckling piglets,but there are few reports on the production performance of weaned piglets.Therefore,in this paper,different quality of Glycyrrhiza polysaccharide was added to the diet to study the effect of Glycyrrhiza polysaccharide on the growth performance,blood physiological and biochemical indicators,intestinal environment and mucosal immunity of weaned piglets.Tract epithelial cells(IPEC-J2)established an in vitro stress inflammatory injury cell model to explore the protective effect and molecular mechanism of Glycyrrhiza polysaccharide,reveal the mechanism of Glycyrrhiza polysaccharide regulating intestinal immune response,and provide a scientific basis for clinical application of Glycyrrhiza polysaccharide.Section1.Effects of Glycyrrhiza polysaccharides on growth performance,blood physiological and biochemical indexes of weaned piglets300 35-day-old "Landrace × Dabai" binary cross weaned piglets with similar body weight and good health were selected and randomly divided into 5 groups with 6 replicates in each group,10 pigs in each replicate,and half male and female.The control group was fed the basal diet,and the experimental group was supplemented with 500,1000,2000 and 5000 mg/kg of Glycyrrhiza polysaccharide in the basal diet,respectively,and the formal test period is 21 days.The results showed that,compared with the control group,①the addition of 1000 mg/kg and 2000 mg/kg Glycyrrhiza polysaccharide in the diet significantly increased the average daily weight gain(ADG)of weaned piglets(P<0.05),and the addition of 500 mg/kg,1000 mg/kg and 2000 mg/kg Glycyrrhiza polysaccharide significantly reduced the diarrhea rate and feedto-weight ratio(F/G)of weaned piglets(P<0.05);②Adding 1000 mg/kg Glycyrrhiza polysaccharide to the diet significantly increased the blood of weaned piglets White blood cell count(WBC),red blood cell count(RBC),neutrophil count(Neut#)and platelet count(PLT)(P<0.05);③Add 1000 mg/kg and 2000 mg/kg licorice to the diet The activity of serum alkaline phosphatase(ALP)of weaned piglets in polysaccharide group was significantly increased(P<0.05),and the content of creatinine(CREA)was significantly decreased(P<0.05).Protein(GLB)content was significantly increased(P<0.05).④The addition of 1000 mg/kg Glycyrrhiza polysaccharide to the diet significantly increased the activity of TAOC in serum and decreased the content of MDA significantly.The blood physiological and biochemical indexes were all within the normal reference range.It shows that adding licorice polysaccharide in the diet can effectively promote the feed intake of weaned piglets,reduce the feed-to-weight ratio and diarrhea rate,improve growth performance,improve blood physiological and biochemical indicators,enhance liver and kidney metabolism,and improve body defense and antioxidant capacity.1000 mg/kg works better.Section 2.Effects of Glycyrrhiza polysaccharides on intestinal mucosal barrier of weaned pigletsIn order to explore the effect of Glycyrrhiza polysaccharide on the intestinal mucosal barrier of weaned piglets,the experimental design was the same as that of Experiment 1.The results showed that,compared with the control group,① Glycyrrhiza polysaccharide supplementation in the diet improved the intestinal physical barrier function of weaned piglets,and the mRNA expression of intestinal tight junction protein-related genes(Claudin-1,Occludin and ZO-1)in the weaned piglets in the Glycyrrhiza polysaccharide group The 1000 mg/kg Glycyrrhiza polysaccharide group significantly increased the villus height and crypt ratio of the small intestine of weaned piglets(P<0.05),and decreased the depth of the small intestinal crypt(P<0.05).The content of Glycyrrhiza polysaccharide in the diet was significantly decreased(P<0.05);②The addition of Glycyrrhiza polysaccharide to the diet improved the intestinal chemical barrier function of weaned piglets,and the pH of the contents of the duodenum of weaned piglets in the 500 mg/kg and 1000 mg/kg Glycyrrhiza polysaccharide groups was significantly decreased(P<0.05);1000 mg/kg Glycyrrhiza polysaccharide group significantly increased the sIgA content of small intestinal mucosa of weaned piglets(P<0.05);1000 mg/kg and 2000 mg/kg Glycyrrhiza polysaccharide groups significantly increased the activities of trypsin,amylase and lipase in the small intestine of weaned piglets increased(P<0.05);③Adding Glycyrrhiza polysaccharide to the diet improved the intestinal immune barrier function of weaned piglets,and the 500 mg/kg and 5000 mg/kg Glycyrrhiza polysaccharide groups significantly down-regulated the mRNA expressions of IL-6 and IL-8 in the small intestinal mucosa(P<0.05),the 1000 mg/kg and 2000 mg/kg Glycyrrhiza polysaccharide groups significantly down-regulated the mRNA expressions of IFN-y,IL-1β,IL-6 and IL-8 in the small intestinal mucosa(P<0.05),and the Glycyrrhiza polysaccharide group significantly The mRNA expressions of IL-2,IL-4,IL-10,TNF-α and TGF-β were up-regulated(P<0.05);④ Glycyrrhiza polysaccharide supplementation in the diet improved the intestinal microbial barrier function of weaned piglets,and Glycyrrhiza polysaccharide significantly changed weaning.The diversity and composition of cecum microbes in piglets,the α-diversity of Glycyrrhiza polysaccharide group was significantly increased(P<0.05);the abundance of Firmicutes was significantly increased(P<0.05),and the abundance of Bacteroidetes was significantly increased(P<0.05).decreased(P<0.05);the abundances of Lactobacillus and Marvinbryantia were significantly increased(P<0.05),and the abundances of Terrisporobacter,Romboutsia,Escherichia coli were significantly increased(P<0.05).The abundance of opportunistic pathogens such as Escherichia-Shigella was significantly decreased(P<0.05).It showed that adding Glycyrrhiza polysaccharide in the diet improved the morphological structure and permeability of the small intestine of weaned piglets,decreased the intestinal pH,increased the activity of digestive enzymes and the content of volatile fatty acids,regulated the mRNA expression of mucosal immunity and tight junction protein-related genes,and enhanced the intestinal mucosal immunity.It can increase the richness and diversity of cecal microbial flora,improve the intestinal health of weaned piglets,and improve the intestinal mucosal barrier function.Section 3.Protective effect of Glycyrrhiza polysaccharide on IPEC-J2 cell injury induced by LPSPorcine intestinal epithelial cells(IPEC-J2)were selected and induced with lipopolysaccharide(LPS)to establish an in vitro stress inflammatory injury cell model.The results showed that compared with the control group,①200～600 μg·L-1 Glycyrrhiza polysaccharide was the optimal concentration and time for 10 μg·mL-1 LPS to treat IPEC-J2 cells for 24 h;②Under LPS stimulation,the ROS level of IPEC-J2 cells increased significantly.(P<0.05),while Glycyrrhiza polysaccharide could significantly reduce the ROS level(P<0.05);③LPS significantly reduced the activities of T-AOC,SOD,GSH-Px in the supernatant of IPEC-J2 cells(P<0.05),and the activity of LDH and MDA content increased significantly(P<0.05);with the increase of Glycyrrhiza polysaccharide treatment concentration,the activities of T-AOC,SOD,GSH-Px gradually increased,and the activity of LDH and MDA content gradually decreased;④JC-1 and DAPI staining showed that,under the stimulation of LPS,the mitochondrial membrane potential of IPEC-J2 cells in the Glycyrrhiza polysaccharide group was increased,and the apoptosis rate was significantly decreased;Apoptosis,tight junction protein and TLR4/MyD88/NF-κB inflammatory pathway-related gene mRNA expression in a dose-dependent manner,IPEC-J2 cells proinflammatory factors(IL-1β,IL-6,IL-8 and TNF-α),apoptosis genes(Bax,caspase-3,caspase-8 and caspase-9)mRNA expression was significantly down-regulated(P<0.05);antiinflammatory factors(IL-4,IL-10),immunoglobulin Protein(IgA,IgG),apoptosis gene Bcl2,tight junction protein(ZO-1,occludin,claudin-1)mRNA expression was significantly upregulated(P<0.05);under the stimulation of LPS,adding 600 μg·mL-1 Glycyrrhiza polysaccharide significantly down-regulated the expression of TLR4,MyD88 and NF-κB mRNA in cells(P<0.05).It shows that Glycyrrhiza polysaccharide can inhibit the TLR4 signaling pathway,reduce the overexpression of immune and inflammation,apoptosis and tight junction protein and other related genes in IPEC-J2 cells induced by LPS,improve the antioxidant capacity of cells,and reduce the accumulation of cellular ROS.and apoptosis rate,alleviate the inflammatory damage of IPEC-J2 cells induced by LPS,and is an immune enhancer that effectively enhances the integrity of the intestinal barrier.In summary,adding 1000 mg/kg Glycyrrhiza polysaccharide to the diet can relieve the stress response of weaned piglets,reduce the diarrhea rate,and improve their growth performance;its mechanism is related to that Glycyrrhiza polysaccharide can improve the intestinal mucosal barrier effect of weaned piglets and improve the growth performance of weaned piglets.It is related to the immune function of the body and the improvement of the structure of the intestinal microflora.It can be seen that Glycyrrhiza polysaccharide has a good application prospect as a feed additive.