The Effect of Tauroursodeoxycholic Acid (TUDCA) Treatment on Pregnancy Outcomes and Uterine Artery Function in a Rat Model of Advanced Maternal Age

Abstract

IntroductionAdvanced maternal age (AMA; ≥35 years) increases the risk of pregnancy complications and adverse pregnancy outcomes such as fetal growth restriction. Endoplasmic reticulum (ER) and oxidative stress have been linked to vascular dysfunction (i.e. reduced nitric oxide [NO] & increased endothelin‐1 [ET‐1] levels) in aging. Tauroursodeoxycholic acid (TUDCA) is an ER and oxidative stress inhibitor and has been shown to improve embryo development in vitro. However, whether treatment with TUDCA can help improve uterine vascular function and pregnancy outcomes in AMA has not been investigated. We hypothesize that TUDCA treatment will improve pregnancy outcomes and vascular function in a rat model of AMA.MethodsYoung (4 months) and aged (9.5 months of age; ~35 years in humans) pregnant control or TUDCA‐treated rats were studied on gestational day 20 (term=22 days). Following euthanasia, pregnancy outcomes (litter size, resorption sites, fetal weight, and placental weight) were recorded, and main uterine arteries were isolated. Endothelium‐dependent vasorelaxation to methacholine (MCh) was assessed by wire myography in the presence/absence of pan NO synthase inhibitor (L‐NAME). In addition, big‐endothelin‐1 (bET‐1) vasoconstriction responses were evaluated, in the presence/absence of endothelin converting enzyme (ECE) inhibitor (CGS). Data summarized as maximum vasodilation response (Emax) and analyzed by two‐way ANOVA with Sidak’s post‐test, p<0.05 was considered significant.ResultsFetal body weights were reduced in AMA control rats compared to young dams (p<0.017), while TUDCA treatment tended to increase fetal body weight in AMA rats (p=0.067); TUDCA did not affect fetal body weight in the young dams. Placental weights, litter size and number of resorptions were similar in all the groups. The maximum relaxation (Emax) to MCh was impaired in the AMA dams compared to young dam (p=0.047), and this reduced relaxation was not evident in the TUDCA treated AMA dams. Ex vivo treatment with L‐ NAME showed an increased contribution of NO in young TUDCA treated rats (ΔEmax [differences in Emax]; p=0.043) compared to young control rats but not in AMA rats. Ex vivo treatment with CGS demonstrated reduced ECE conversion in young TUDCA treated rats (Emax; p<0.001), while CGS had no effect in the young control dams or both AMA groups.ConclusionOur study assessed TUDCA as an intervention to improve the pregnancy outcomes in a rat model of AMA. An increased fetal body weight suggests a beneficial effect of TUDCA in AMA pregnancies. However, contrary to our hypothesis, in young dams, TUDCA increased NO contribution and reduced ECE effect, but did not affect uterine artery function in AMA dams. Nevertheless, TUDCA has the potential to improve pregnancy outcomes in complicated pregnancies, but further studies are warranted.