Investigating ovine placentome blood perfusion using power flow Doppler ultrasonography

Authors: LEMLEY, CALEB - Mississippi State University; BOWERS, KARRIGAN - Mississippi State University; YANKEY, KALISHA - Mississippi State University; TU, MAGGIE - Mississippi State University; HART, CAITLIN - Mississippi State University; STEADMAN, CHRISTY - Mississippi State University; MCCARTY, KEELEE - Mississippi State University; OWEN, MEGAN - Mississippi State University

Submitted to: Small Ruminant Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/16/2020
Publication Date: 1/17/2020
Citation: Lemley, C., Bowers, K., Yankey, K., Tu, M., Hart, C., Steadman, C., Mccarty, K., Owen, M. 2020. Investigating ovine placentome blood perfusion using power flow Doppler ultrasonography. Small Ruminant Research. 184:106051.

Interpretive Summary: Increasing evidence in livestock species have associated poor growth performance of offspring born to mothers with decreased blood flow to the uterus and placenta, which accounts for a substantial loss in livestock production. Knowledge from animal models of fetal growth restriction will allow for the development of management strategies to mitigate potential production losses associated with the consequences of programming the offspring via the maternal environment. As such, development of quick and efficient techniques to screen alterations in placental blood flow following therapeutic administration could be used to elucidate specific supplements that could improve fetal growth. In this study we determined that power flow Doppler ultrasonography could be used to detect acute changes in placental blood flow allowing for rapid screening of antioxidant therapeutics.

Technical Abstract: Increasing ovine placentome blood perfusion improves placental efficiency while increasing the likelihood of healthier birth weights and lower mortality rates in offspring. Invasive surgical techniques have been used to examine uteroplacental blood flow; however, non-invasive Doppler ultrasonography has recently been observed as a reliable alternative method. Even so, smaller tissues, such as placentomes, do not permit reliable measurements of vessel diameter and subsequently blood flow calculations. Objectives were to validate Doppler ultrasonography techniques for examining placentome blood perfusion in ewes administered vasoactive compounds. Ewes (n=28) were bred to a single ram, with pregnancy being confirmed prior to experimentation. For experiment 1, placentome blood perfusion was determined pre-infusion (PRE1; n=8) and 3–5 minutes post i.v. infusion with sodium nitroprusside at 5 µg/kg of body weight (SN5; n=4) or 10 ug/kg of body weight (SN10; n=4). Immediately after ultrasonography all ewes were administered N(G)-Nitro-L-arginine methyl ester (LNAME) at 12.5 mg/kg of body weight (n=8) and imaged for placentome perfusion 30 min post i.v. infusion. For experiment 2, ewes (n=15) were first imaged for placentome perfusion prior to the administration of antioxidants (min 0; PRE2) and then 30 min following i.v. infusion of melatonin (MEL; 100 ug/kg of body weight), ascorbate (ASC; 10 mg/kg of body weight), or vehicle (VEH; 50% ethanol solution). Data for experiment 1 and 2 were analyzed separately by ANOVA with least significant difference test. For experiment 1, the percent area of placentome perfusion was not different (P > 0.05) between SNP and L-NAME infusions. However, the summation and average integrated pixel density of placentomes were increased (P < 0.05) in SN10 versus PRE1 and L-NAME. For experiment 2, the percent area of placentome perfusion was increased (P < 0.05) in both MEL and ASC versus VEH. In summary, power flow Doppler ultrasonography can be used to detect acute fluctuations in placentome blood perfusion as indicated by changes in integrated pixel density following administration of nitric oxide agonist and antagonist. In addition, acute infusions of antioxidants increased percent area of placentome blood perfusion, which could be used to efficiently screen novel therapeutics that would improve placental efficiency and fetal development.