Differential microRNA (miRNA) expression levels have been reported for placental tissues in cases of uteroplacental insufficiency and fetal growth restriction. Ergot alkaloids found in endophyte-infected tall fescue [Lolium arundinaceum (Schreb.) Darbysh] seed induces intrauterine growth restriction (IUGR) due to uteroplacental insufficiency. The objective of a recent study by researchers from Clemson University was to assess the impact on placental miRNA levels due to consumption of ergot alkaloids during mid to late gestation.

Thirty-six Suffolk ewes (78.24 kg ± 9.5) estimated to be carrying twins at d 35 of gestation were randomly assigned to 1 of 2 treatments—endophyte-free tall fescue seed (E−; 0.0 µg ergovaline + ergovalinine/g) or endophyte-infected tall fescue seed (E+; 4.14 µg ergovaline + ergovalinine/g)—from d 35 through 85 and d 86 through 133 of gestation, creating 4 unique dietary treatments: E−E−, E−E+, E+E−, and E+E+. Endophyte-infected tall fescue seed was fed at a level to provide 1,772 µg of ergovaline + ergovalinine/ewe per day for E+ treatments, and an equal weight of endophyte-free seed (0.0 µg ergovaline + ergovalinine) was fed for E− treatments. Ewes were pair fed across treatments in order to maintain equal DMI. Fetal and maternal necropsies were performed at d 133 of gestation. Placental samples were weighed, frozen in liquid nitrogen, and stored at −80°C. Total RNA was extracted from cotyledon placental tissue using TRIzol and a PureLink RNA Mini Kit (ThermoFisher Scientific). Total RNA was quantified and quality was assessed using an Agilent 2100 Bioanalyzer. Ribonucleic acid integrity numbers of >7 were considered sufficient quality. A subsample (n = 4) was selected for both the E+E+ and E−E− treatment groups, and total cotyledon RNA was submitted for gene expression profiling via RNA sequencing. Numerous miRNA transcripts were upregulated (P < 0.01; n = 15) in E+E+ compared with E−E− and included miR-21, miR-221, miR-99a, miR-152, miR-381, miR-30a, miR-143, and miR-122. miR-21 exhibited a 9.89-fold increase in expression level for E+E+ compared with E−E−.

miR-21 has previously been implicated as a potential biomarker for fetal hypoxia due to upregulation in both placental and plasma/serum samples. Similar increases in miR-21 and miR-122 levels have been correlated to other pathological diseases of the placenta including placental insufficiency, IUGR, and preeclampsia.

 

Reference
J.L. Britt, A. Feltus, M.F. Miller Jr., B.M. Koch, M.C. Miller, S.K. Duckett (2017) 324 Altered expression of placental microRNA in ewes with uteroplacental insufficiency due to consumption of endophyte-infected tall fescue seed J. Anim. Sci. 95(Suppl4):160-160 doi: 10.2527/asasann.2017.324 [abstract]

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