Polymorphism of the Oxytocin Receptor (OXTR) Gene Affects the Circulating Oxytocin Receptor Levels in Late-Term Pregnancy in a Turkish Population

Abstract

Introduction: Postterm and late-term pregnancies still remain a serious health problem, and underlying exact mechanisms are not fully elucidated. These mechanisms are influenced by many factors. Objective: The aim of this study was to investigate the relationship between plasma oxytocin and oxytocin receptor levels and oxytocin receptor polymorphisms in term and late-term pregnant women. Methods: Sixty-eight singleton pregnant women with late-term pregnancy and 83 singleton pregnant women with term parturition were included in this study. A comparison was performed between pregnancies and neonates born at term (37 0/7 and 41 6/7 weeks’ gestation). Plasma oxytocin, oxytocin receptor, estradiol, and progesterone levels were measured by using enzyme-linked immunosorbent assay kits. TaqMan® SNP Genotyping Assays and qPCR ProbesMaster were used to investigate the polymorphisms of rs237911, rs2228485, rs53576, and rs2254298. Results: There was not any difference in gene distributions of 4 common single-nucleotide polymorphisms of oxytocin receptor of rs237911, rs2228485, rs53576, and rs2254298 between subjects in late-term and term pregnancy groups. With rs53576 of the GG genotype, serum oxytocin levels were 21.50 ± 10.69 (ng/L) in the late-term group and 62.71 ± 18.01 (ng/L) in the term group (p = 0.049). Oxytocin receptor levels in the late-term and term pregnancy groups of the GG genotype were 17.92 ± 8.15 (pg/mL) and 45.77 ± 11.66 (pg/mL), respectively (p = 0.046). Conclusion: Our findings suggest that the rs53576 oxytocin receptor single-nucleotide polymorphism is associated with late-term pregnancy through acting by direct modulation of oxytocin and oxytocin receptor levels.