Effect Of IUGR On Development And Endocrine Function Of Pancreas And The Nutritional Regulation By L-arginine In Pigs

Intrauterine growth retardation(IUGR)has adverse effects on pancreas development and pancreatic endocrine function.IUGR piglets show a lower pancreas weight,higher apoptosis of pancreatic beta cells and decreased insulin synthesis and secretion,thus hindering the growth and metabolism of piglets.In current study,the difference of pancreas development and pancreatic endocrine function between IUGR and normal birth weight(NBW)piglets from birth to slaughter age(160 d)was investigated.Meanwhile,the mechanism of IUGR impaired pancreas development was also studied.Furthermore,artificial milk supplementation with 0.6%L-arginine(Arg)was involved to regulate the postnatal development of pancreatic beta cells in suckling piglets under IUGR.Pregnant sows diets with different protein levels supplementation with 1.0%L-arginine,to investigate the long-term effects of L-arginine on pancreatic beta cell growth and function in the offspring,as well as its mechanism.1 Effect of IUGR on postnatal pancreas growth and development in pigs40 NBW and 40 IUGR newborn piglets(Duroc ×(Landrace × Yorkshire))were selected to set two groups,each of which had 4 replicates of 10 pigs per replicates.All piglets were weaned at 21 days of age,and received the same diets(NRC,1998)with ad libitum feeding and drinking after weaning.At 1,7,21,28,66,and 160 days of age,4 pigs in each group with close body weight were chosen to slaughter and sample.The absolute and relative weight of pancreas were weighted and calculated,and the pancreatic insulin content was measured.Furthermore,pancreatic morphological measurements,insulin expression,the apoptosis and proliferation of beta cells were measured.All data were analyzed by t-test using SPSS software.The results showed that,(1)Compared with NBW piglets,IUGR decreased the body weight(P<0.05?P<0.01)and pancreas weight(P<0.05)except 160 days of age,which suggested a limited growth.(2)IUGR decreased pancreatic insulin content(P<0.05)except 28 days of age and the average staining islet optical density(AOD)except for 66 days of age,showed reduced insulin synthesis and reserve.(3)Islet area was significantly reduced,and the number of pancreatic islets decreased significantly(P<0.05 ? P<0.01)in IUGR pigs at 7,21,28 and 66 days of age.Beta cell size decreased significantly in IUGR pigs at 1,7,21,66 days of age(P<0.05?P<0.01).The proportion of beta cell(BCF)except for 1 d was significantly decreased(P<0.05 ?P<0.01)in IUGR pigs,as well as the area of insulin positive expression.Beta cell mass(BCM)except for 21 d were significantly decreased(P<0.05)in IUGR pigs.(4)IUGR leads to beta cell proliferation index(PI)decreasing significantly(P<0.01),apoptosis index(AI)and AI/PI significantly increasing(P<0.01 or P<0.05).2 Regulation of L-arginine on IUGR piglet pancreatic growth and developmentSelected 12 IUGR piglets and 6 NBW piglets,natural breast-feeding to 7 days of age,the IUGR piglets were randomly divided into two groups(n=6),feeding with artificial milk(IUGR)and artificial milk supplementation with 0.6%Arg(IUGR+Arg),and NBW piglets fed with artificial milk(NBW).At 14 days of age,4 pigs in each group with close body weight were chosen to slaughter and sample.Measurements were the same as experiment 1.Analysis of the data were analyzed by one-way ANOVA using SPSS software.The results showed that,(1)Body weight of IUGR piglets was significantly increased after arginine supplementation(P<0.05),but pancreatic weight had no significant difference between the groups(P>0.05).(2)pancreatic insulin content in IUGR piglets supplementation with arginine was significantly increased(P<0.05),the average optical density was significantly increased(P<0.01).(3)Islet area,the number of pancreatic islets and insulin expression positive cell,the proportion of beta cells and beta cell mass were significantly increased(P<0.01)in IUGR piglets supplementation with arginine,and beta cell size increased significantly(P<0.05).(4)PI of beta cell was significantly increased(P<0.05),and AI/PI decreased significantly(P<0.05)in IUGR piglets supplementation with arginine.3 Effects of sows diets supplemented with arginine on the growth and pancreas development of the offspring40 sows divided into 4 groups:group Prol(feeding basal diet with 15.2%protein),Prol+Arg(15.2%protein level diets supplemented with 1%arginine),Pro2(feeding basal diet with 13.2%protein)and Pro2+Arg(13.2%protein level of basic diet supplemented with 1%arginine).After the birth,20 NBW and 20 IUGR piglets were selected from each group,and all piglets were weaned at 21 days of age,then were fed with the same normal diet.At 7,21,200 days of age,4 NBW piglets and 4 IUGR piglets in each group with close body weight were chosen to slaughter and sample.Pancreas weight,serum hormone,and antioxidant index were measured.Data analysis using GLM model for three factor analysis of variance with SPSS software,the results show that:(1)Arginine significantly increased the litter size,and litter weight(P<0.01),reduced the incidence of IUGR,but the difference was not significant(P>0.05).Pro2 reduced the litter size and litter weight(P<0.05).(2)IUGR decreased body weight and pancreas weight significantly(P<0.05 or P<0.01).Effects of Arg and Pro2 on body weight and pancreas weight was not significantly(P>0.05).(3)IUGR significantly increased serum glucagon level at 21 and 200 days(P<0.01),reduced insulin level at 7 and 21 days and the level of leptin at 7 and 200 days(P<0.05 or P<0.01).Arginine significantly increased serum glucagon at 7 day(P<0.01),but reduced it at 21 and 200 days(P<0.01).Pro2 increased serum insulin level(P<0.01),decreased GH level at 21 and 200 days(P<0.05 or P<0.01),increasing cortisol and glucagon levels at 7 and 21 days(P<0.Ol).(4)Serum glucose level of IUGR pigs was significant increased at 7 and 200 days(P<0.01),and FFA was significant increased at 7 and 21 days(P<0.01).Pro2 increased the level of serum FFA at 7 and 200 days(P<0.01).(5)IUGR increased pancreatic MDA content(P<0.01),decreased the content of T-AOC and GSH(P<0.01 or P<0.05),decreased the activity of Mn-SOD(P<0.01 or P<0.05).Arg significantly reduced pancreatic MDA content(P<0.05),increased the content of T-AOC(P<0.01 or P<0.05)in offspring.Pro2 decreased the activity of Mn-SOD and GSH-Px(P<0.01 or P<0.05)in offspring.4 Effects of sows diets supplemented with arginine on pig pancreatic beta cell developmentExperimental design was the same as experiment 3,detected pancreatic beta cell number,beta cell proliferation and apoptosis,and gene expression of mRNA related to beta cell development.The results show that:(1)IUGR decreased the number of islet cells(P<0.01)and islet area(P<0.01).Arg increased the number of islet cells(P<0.01)and islet area(P<0.01)of the offspring.Pro2 reduced the number of islet cells(P<0.01)and islet area(P<0.05)of the offspring.(2)IUGR decreased BCM(P<0.01),insulin positive area(P<0.01),and the average staining optical density(P<0.01).Arg increased those indexes of the offspring(P<0.05).Pro2 only reduced the BCM at 7 and 21 days in the offspring(P<0.01 or P<0.05).(3)IUGR decreased PI of pancreatic beta cell(P<0.01 or P<0.05),increased AI,AI/PI(P<0.01).Arg improves PI of pancreatic beta cell at 7 and 21 days(P<0.05),and significantly decreased AI,AI/PI(P<0.01 or P<0.05).(4)IUGR reduced pancreas mRNA expression of PDX1 at 7 and 21 days(P<0.05);increased the expression of FOXO1 at 7 and 21 days(P<0.01 or P<0.05),and increased the expression of BAX(P<0.01 or P<0.05).Arg increased pancreatic PDX1 mRNA expression at 7 and 21 days(P<0.05),reduced the expression of FOXO and BAX(P<0.01 or P<0.05).5 Effects of sows diets supplemented with arginine on pig pancreatic beta cell functionExperimental design was the same as experiment 3,detected gene expression of mRNA related to insulin secretion.The results show that:(1)IUGR reduced pancreatic mitochondrial Na+-K+-ATP,Ca2+-ATP enzyme activity(P<0.01 or P<0.05),as well as the activity of MDH and SDH(P<0.01).Arg improved mitochondrial Na+-K+-ATP enzyme activity of the offspring at 7 and 21 days(P<0.01 or P<0.05).(2)IUGR decreased pancreas mRNA expression of NDUFA13(P<0.05)and UQCRB(P<0.05),increased UCP-2 expression(P<0.05),decreased insulin mRNA expression(P<0.05).Arg improved the expression of pancreatic INS at 7 and 21 days(P<0.01).(3)IUGR decreased the expression of SUR1,Kir6.2 and Cavl mRNA(P<0.05 or P<0.01).Arg and Pro2 had no significant effects(P>0.05).(4)IUGR decreased the expression of SYN1a,Muncl3a and SYT1 mRNA(P<0.01 or P<0.05).Arg improved the expression of pancreatic Muncl3a(P<0.01).