Expression of Placental Growth Factor and Endoglin in the pregnant rat during episodic reductions in uterine perfusion
Authors: Walro Derek , Balser Brittany , Berger Sarah , Underwood Adam , Ramirez Rolando JJ , Novak Jacqueline 
Published: June 2021

Endoglin (ENG) and placental growth factor (PGF) have been identified as potential markers of preeclampsia (PE). Most studies measure serum levels of these factors after PE diagnosis or sampling from the placentae after delivery; therefore these studies do not allow investigation into the progression of the disease. Animal models for PE may not mimic every aspect of the disease; however, they do allow studies unfeasible in humans such as time course studies. We examined the time course of placental expression of ENG and PGF in an animal model of preeclampsia. The animal model we chose for this study is one in which uterine blood flow is decreased about 40% episodically via an aortic occluder (Occluder model). Previous studies by our lab have shown significant increases in maternal blood pressure and fetal growth restriction in this model comparable to the more commonly studied chronic reduced uterine perfusion pressure model (RUPP). For the Occluder model, Sprague‐Dawley dams were anesthetized on gestational day 14. An abdominal incision was made to implant silver clips (0.1mm i.d.) on the utero‐ovarian arteries and a silastic vascular occluder on the abdominal aorta below the renal arteries. Occluder animals were subjected to one hour of occlusion (40% reduction in blood pressure) for one hour each day for one, three or five days (gestational days 15, 17 and 19). SHAM rats undergo surgery without occluder and clip placement. At the end of the experiment, the uterus was excised and fetal data was recorded. Placental tissue samples were flash frozen. RT‐qPCR was performed on placental samples for ENG and PGF. Total RNA was then extracted using the Direct‐zol™ RNA isolation Kit (Zymo Research) and cDNA synthesis was completed using the Maxima First Strand cDNA Synthesis Kit (Thermo). TaqMan® assays were used to determine the relative expression of ENG and PGF using comparative CT (ΔΔCT) analysis. We hypothesized that expression of ENG would increase and expression of PGF would decrease in the Occluder model compared to control (SHAM) rats. However, no significance was observed between SHAM and Occluder at day 5 of occlusion (gestational day 19) for ENG or PGF. Occluder rats showed an increase in ENG across the time courses with day 5 of occlusion (gestational day 19) being the highest; however, this change failed to reach statistical significance in these preliminary studies.

For PGF the highest expression was at day 3 of occlusion (gestational day 17). There was an increase from day 1 of occlusion (gestational day 15) to day 3 occlusion (gestational day 15) but then levels decreased at day 5 of occlusion (gestational day 19). However, there was no reportable statistical significance. Placental expression of PGF and endoglin in the Occluder model did not seem to correlate with the studies that have measured serum levels of PGF and endoglin in PE. The time course studies suggest that the expression in the uterus is changed following episodic reduction in uterine perfusion but further studies are needed to confirm the findings and to examine correlations with serum levels in the Occluder model.

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.