The Effect Of Feed Intake Restriction During Pregnancy On The Development Of Placenta And Placental Protein Expression Profiling In Goat

This study investigated the effect of restricted feeding nutrition during pregnancy on the development goat placenta.Meanwhile,it discussed the relationship between insufficient nutrition supply and placental morphology,nutrient transport,blood flow and vascular development,and explored the potential pathways of nutrient transportation.Twenty-four healthy Liuyang black pregnant goats with closely oestrus time were chosen for experiments,the early feed restriction experiment was conducted during 26-65 d of pregnant,twelve goats were randomly divided into control group(CG)and 40% ad libitum feeding restriction group(RG),each group had 6 goats.The goats were sacrificed at the end of the experiment,the blood of mother goats,placentas,and fetal goats were collected.Uterine caruncle and cotyledon sperated from placenta were counted and weighted.The late feed restriction experiment was conducted during 95-125 d of pregnant,and the procedure was the same as the early feed restriction experiment.The placenta morphology index including: placental weight,uterine caruncle and cotyledon weight,the amount of uterine caruncle and cotyledon,fetal weight,relative weight of placenta,relative weight and average weight of uterine caruncle,relative weight average weight of cotyledon,cotyledon density and cotyledon capillary density,which was detected by immunohistochemistry in late pregnancy.The indices of placental growth factors including: vascular endothelial growth factor(VEGF),bile acid(TAB),nitric oxide(NO),and nitric oxide synthase(NOS),which were detected by ELISA,in mother goats serum,as well as the content of nitric oxide(NO)in cotyledon and uterine caruncle tissues;the expression of VEGFA,KDR(VEGFr2),NOS1 and NOS2 mRNA,which were detected by Real-time quantitative PCR,in cotyledon and uterine caruncle tissues;differential proteins,which were detected by ITRAQ technique,in cotyledon.The results indicated that:1.Feed restriction in early pregnancy significantly increased(P < 0.05)the placenta weight and relative weight,uterine caruncle weight and relative weight,cotyledon weight and relative weight,as well as fetal weight.The relative weight of placenta,cotyledon relative weight and fetal weight had an extremely significant increase(P < 0.01).In the early stage of pregnancy,feed intake restriction facilitated the development of the placenta,and increased the growth of the fetus.2.Feed restriction in late pregnancy significantly increased(P <0.05)the placental weight,but significantly decreased the weight of fetal goats(P < 0.05)and the capillary density in the cotyledon(P < 0.01).In the early stage of pregnancy,feed intake restriction increased the placenta weight,but reduced the capillary density of placental cotyledon and inhibited the growth of fetal goats.3.Feed restriction in early pregnancy significantly increased(P < 0.05)the content of NO in the serum of mother goats,and enhanced(P < 0.1)the expression of NOS2 gene in uterine caruncle,but decreased(P < 0.1)the content of NO in placental cotyledon.Since the supply of nutrients to the fetus is controlled by NO in maternal goat’s blood,and the fetal maternal nutrition absorption is controlled by NO in cotyledon,the increase of NO in maternal goat’s serum might be the primary factor,in a manner,that significantly promote the growth of fetus.104 proteins were detected in the placental cotyledon in early pregnancy,and 50 differentially expressed proteins were identified.Among them,there were 27 up-regulated proteins and 23 down-regulated proteins.Analysis of the difference of protein bioinformatics indicated that the up-regulated proteins are related to proliferation and fission of trophoblast cell and the placenta angiogenesis.That may partially explain the promoted placenta growth in the restricted feeding during early pregnancy.4.Feed restriction in late pregnancy had no significant effect on serum NO content index of mother goats,but decreased(P < 0.1)the content of NO in placental cotyledon,and increased(P < 0.1)the NOS1 mRNA of uterine caruncle.The inhibited growth of fetus may be related to the decreased NO concentration,since fetal maternal nutrition is mainly controlled by NO in cotyledon.149 proteins were detected in the placental cotyledon in late pregnancy,and there were 58 differentially expressed proteins,of which,there were 38 up-regulated proteins and 20 down regulated proteins.The up-regulated proteins were related to placenta formation,blood flow regulation and embryonic development.There is certain relation between the down regulated proteins and the placental trophoblasticcell migration and vascular blood flow regulation.That may partially explain feed restriction in late pregnancy promoted placenta growth but reduced the density of capillary.