Department of Women's and Children's Health, Section of Obstetrics and Gynecology, Uppsala University, Uppsala, Sweden.
Department of Chemistry - BMC, Analytical Chemistry and Neurochemistry, Uppsala University, Uppsala, Sweden.
Am J Reprod Immunol. 2023 Sep;90(3):e13767. doi: 10.1111/aji.13767.
The exact biochemical mechanisms that initiate labor are not yet fully understood. Nitric oxide is a potent relaxant of uterine smooth muscles until labor starts, and its precursor is L-arginine. Asymmetric (ADMA) and symmetric (SDMA) dimethylarginines, are potent NO-inhibitors. However, arginines (dimethylarginines and L-arginine) are scarcely studied in relation to labor and childbirth. We aimed to investigate arginines in women with spontaneous (SLVB) and induced (ILVB) term labor with vaginal birth and in women undergoing elective caesarean section (ECS).
Women at gestational week 16-18 were recruited to the population-based prospective cohort study BASIC at the Uppsala University Hospital, Sweden. Plasma samples taken at start of labor were analyzed for arginines, from SLVB (n = 45), ILVB (n = 45), and ECS (n = 45), using Ultra-High Performance Liquid Chromatography. Between-group differences were assessed using Kruskal-Wallis and Mann-Whitney U-test.
Women with SLVB and ILVB had higher levels of ADMA (p < .0001), SDMA (p < .05) and lower L-arginines (p < .01), L-arginine/ADMA (p < .0001), and L-arginine/SDMA (p < .01, respectively <.001) compared to ECS. However, ILVB had higher ADMA (p < .0001) and lower L-arginine (p < .01), L-arginine/ADMA (p < .0001), and L-arginine/SDMA (p < .01) compared to SLVB. Results are adjusted for gestational length at birth and cervical dilatation at sampling.
Our novel findings of higher levels of dimethylarginines in term vaginal births compared to ECS give insights into the biochemical mechanisms of labor. These findings might also serve as a basis for further studies of arginines in complicated pregnancies and labor.
启动分娩的确切生化机制尚未完全阐明。一氧化氮（NO）是一种强有力的子宫平滑肌松弛剂，直到分娩开始，其前体是 L-精氨酸。不对称二甲基精氨酸（ADMA）和对称二甲基精氨酸（SDMA）是强有力的 NO 抑制剂。然而，关于分娩和分娩，精氨酸（二甲基精氨酸和 L-精氨酸）的研究甚少。我们旨在研究自发性（SLVB）和诱导性（ILVB）足月分娩伴阴道分娩以及选择性剖宫产（ECS）的女性中的精氨酸。
在瑞典乌普萨拉大学医院，招募了处于妊娠 16-18 周的女性，参加基于人群的前瞻性队列研究 BASIC。分娩开始时采集的血浆样本，使用超高效液相色谱法分析 ADMA（n=45）、SDMA（n=45）和 ECS（n=45）中的精氨酸。使用 Kruskal-Wallis 和 Mann-Whitney U 检验评估组间差异。
与 ECS 相比，SLVB 和 ILVB 的女性 ADMA 水平更高（p<.0001），SDMA 水平更高（p<.05），L-精氨酸水平更低（p<.01），L-精氨酸/ADMA 比值更低（p<.0001），L-精氨酸/SDMA 比值更低（p<.01，分别<.001）。然而，与 SLVB 相比，ILVB 的 ADMA 水平更高（p<.0001），L-精氨酸水平更低（p<.01），L-精氨酸/ADMA 比值更低（p<.0001），L-精氨酸/SDMA 比值更低（p<.01）。结果根据出生时的妊娠长度和采样时的宫颈扩张进行了调整。
我们的新发现表明，与 ECS 相比，足月阴道分娩中二甲基精氨酸水平较高，这为分娩的生化机制提供了新的认识。这些发现也可以为进一步研究复杂妊娠和分娩中的精氨酸提供基础。
