Morphologic Changes of the Uteroplacental Unit in Preeclampsia-Like Syndrome in Rats

Abstract

Objective: Chronic administration of the nitric oxide synthase inhibitor NG-nitro-L-arginine methylester (L-NAME) induces a preeclampsia-like syndrome in rats. This animal study aims to determine whether L-NAME–induced preeclampsia-like syndrome is also associated with morphologic changes in the uteroplacental unit. Methods. Mating was induced in 20 adult Sprague-Dawley rats. On day 14, five pregnant rats were randomly assigned to receive L-NAME, whereas six served as controls. Weight, continuous blood pressure, urine volume, urine protein content, litter size, number of resorption sites, placental weight, and weight of pups were documented. Uteroplacental tissue of three L-NAME and three control animals were processed for microscopy using corrosion cast technique. Results. The L-NAME–treated animals had a significantly smaller litter size (p = .033) and a significantly higher number of resorption sites (p = .021) when compared to controls. In L-NAME–treated rats midlength inner-diameter of maternal arterial channels (p < .001) and cross-sectional area (p < .001) were significantly smaller than were those incontrols. Conclusions. Chronic administration of L-NAME to pregnant rats is associated with significant morphologic changes of the uteroplacental vasculature. The L-NAME–induced pathologic alterations resulted in decreased litter size and increased number of resorption sites that may be contributed to diminished uteroplacental perfusion.