Pre-implantation exogenous progesterone and pregnancy in sheep.II.Effects on fetalplacental development and nutrient transporters in late pregnancy

Background:Administration of progesterone(P4)to ewes during the first 9 to 12 days of pregnancy accelerates blastocyst development by day 12 of pregnancy,likely due to P4-induced up-regulation of key genes in uterine epithelia responsible for secretion and transport of components of histotroph into the uterine lumen.This study determined if acceleration of blastocyst development induced by exogenous P4 during the pre-implantation period affects fetal-placental development on day 125 of pregnancy.Suffolk ewes(n=35)were mated to fertile rams and assigned randomly to receive daily intramuscular injections of either corn oil vehicle(CO,n=18)or 25 mg progesterone in CO(P4,n=17)for the first 8 days of pregnancy.All ewes were hysterectomized on day 125 of pregnancy and:1)fetal and placental weights and measurements were recorded;2)endometrial and placental tissues were analyzed for the expression of candidate mRNAs involved in nutrient transport and arginine metabolism;and 3)maternal plasma,fetal plasma,allantoic fluid,and amniotic fluid were analyzed for amino acids,agmatine,polyamines,glucose,and fructose.Results:Treatment of ewes with exogenous P4 did not alter fetal or placental growth,but increased amounts of aspartate and arginine in allantoic fluid and amniotic fluid,respectively.Ewes that received exogenous P4 had greater expression of mRNAs for SLC7A1,SLC7A2,SLC2A1,AGMAT,and ODC1 in endometria,as well as SLC1A4,SLC2A5,SLC2A8 and ODC1 in placentomes.In addition,AZIN2 protein was immunolocalized to uterine luminal and glandular epithelia in P4-treated ewes,whereas AZIN2 localized only to uterine luminal epithelia in CO-treated ewes.Conclusions:This study revealed that exogenous P4 administered in early pregnancy influenced expression of selected genes for nutrient transporters and the expression of a protein involved in polyamine synthesis on day 125 of pregnancy,suggesting a‘programming’effect of P4 on gene expression that affected the composition of nutrients in fetal-placental fluids.

Pre-implantation exogenous progesterone and pregnancy in sheep:I.polyamines,nutrient transport,and progestamedins

Background:Administration of exogenous progesterone(P4)to ewes during the pre-implantation period advances conceptus development and implantation.This study determined effects of exogenous P4 on transport of select nutrients and pathways that enhance conceptus development.Pregnant ewes(n=38)were treated with either 25 mg P4 in 1 mL corn oil(P4,n=18)or 1mL corn oil alone(CO,n=20)from day 1.5 through day 8 of pregnancy and hysterectomized on either day 9 or day 12 of pregnancy.Endometrial expression of genes encoding enzymes for synthesis of polyamines,transporters of glucose,arginine,and glycine,as well as progestamedins was determined by RT-qPCR.Results:On day 12 of pregnancy,conceptuses from P4-treated ewes had elongated while those from CO-treated ewes were spherical.The mRNA expression of AZIN2,an arginine decarboxylase,was lower in endometria of P4-treated than CO-treated ewes on day 9 of pregnancy.Expression of FGF10,a progestamedin,was greater in endometria of CO and P4-treated ewes on day 12 of gestation in addition to P4-treated ewes necropsied on day 9 of gestation.Treatment with P4 down-regulated endometrial expression of amino acid transporter SLC1A4 on day 12 of pregnancy.Conclusions:Results indicated that administration of exogenous P4 during the pre-implantation period advanced the expression of FGF10,which may accelerate proliferation of trophectoderm cells,but also was correlated with decreased expression of glycine and serine transporters and polyamine synthesis enzyme AZIN2.Further research with increased sample sizes may determine how differential expression affects endometrial functions and potentially embryonic loss.