Submitted to: Animal Reproduction Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/18/2021
Publication Date: 9/23/2021
Citation: Wilhelm Rodrigues, B., Ticiani, E., Campagnolo, K., Rodrigues, J.L., Roberts, A.J., Anderson, G.B., Bertolini, M. 2021. Components of the insulin-like growth factor system in in vivo- and in vitro-derived bovine pregnancies and neonates, and their association with conceptus growth. Animal Reproduction Science. 234. Article 106856. https://doi.org/10.1016/j.anireprosci.2021.106856.
DOI: https://doi.org/10.1016/j.anireprosci.2021.106856

Interpretive Summary: In vitro embryo production has been implicated in the appearance of excessive birth weights and abnormal placental development in cattle. Disturbances in placentation function may cause abnormal fetal growth. This experiment was designed to study mechanisms affecting growth of in vivo- and in vitro-derived bovine concepti. Day-7 in vitro-produced (IVP) or in vivo-derived (IVD, control) bovine blastocysts were transferred to synchronous recipients, with pregnant females either slaughtered on Days 90 or 180 of gestation or allowed to go to term. An increase in fetal weight was observed in the IVP group, which was associated with increased concentrations of both insulin-like growth factors 1 and 2 (IGF-1 and IGF-2) in the maternal circulation, and changes in profiles of insulin-like growth factor binding proteins (IGFBP) within fetal fluids. Day-90 IVP pregnancies displayed longer fetuses, greater organ weights, larger placentomes, lower placentome transcription of IGF-2 receptor (IGF-2r), and greater maternal circulating concentrations of IGF-1 and IGF-2 than controls. On Day 180 and at term, IVP pregnancies presented larger uteri, placentomes/fetal membranes, fetuses/calves, greater fetal hepatic transcription of IGF-2, lower fetal plasma IGF-1 and higher allantoic IGF-2 concentrations, increased and decreased IGFBP activities in the allantoic and amniotic fluids, respectively, and greater glucose and fructose accumulation in fetal fluids. Components of the IGF system were differentially regulated not only according to the gestation period (Days 90 or 180) and fluid type (maternal or fetal plasma, amniotic or allantoic fluids), but also based on conceptus origin (IVP or IVD) in cattle.

Technical Abstract: This experiment was designed to study mechanisms affecting growth of in vivo- and in vitro-derived bovine concepti. Day-7 in vitro-produced (IVP) or in vivo-derived (IVD) bovine blastocysts were transferred to synchronous recipients, with pregnant females either slaughtered on Days 90 or 180 of gestation or allowed to go to term. Uteri and contents were dissected and physically measured, and maternal and fetal plasma and amniotic and allantoic fluids were collected for IGF-1 and IGF-2 determinations, and IGFBP profile characterization. Transcripts for IGF-1 and IGF-2 in placental and fetal tissues, and IGF-1r and IGF-2r in placentomes were determined by real-time quantitative PCR. An increase in fetal weight was observed in the IVP group, which was associated with increased IGF-1 and IGF-2 concentrations in the maternal circulation, and changes in the IGFBP profiles within fetal fluids. Day-90 IVP pregnancies displayed longer fetuses, greater organ weights, larger placentomes, lower placentome IGF-2r relative transcription, and higher maternal IGF-1 and IGF-2 concentrations than controls. On Day 180 and at term, IVP pregnancies presented larger uteri, placentomes/fetal membranes, fetuses/calves, higher fetal hepatic IGF-2 relative transcription, lower fetal plasma IGF-1 and higher allantoic IGF-2 concentrations, increased and decreased IGFBP activities in the allantoic and amniotic fluids, respectively, and greater glucose and fructose accumulation in fetal fluids. Components of the IGF system were differentially regulated not only according to the gestation period (Days 90 or 180) and fluid type (maternal or fetal plasma, amniotic or allantoic fluids), but also based on conceptus origin (IVP or IVD) in cattle.