Oxidative stress (OS), an imbalance between free radical generation and antioxidant defence, is recognized as a key factor in the pathogenesis of adverse pregnancy outcomes. Although OS is a common future of normal pregnancy, persistent, overwhelming OS leads to consumption and decline of antioxidants, affecting placental antioxidant capacity and reducing systems. The accumulation of OS causes damage to lipids, proteins and DNA in the placental tissue that induces a form of accelerated ageing.Premature ageing of the placenta is associated with placental insufficiency that prevents the organ meeting the needs of the foetus, and as a consequence, the viability of the foetus is compromised. This review summarizes the literature regarding the role of OS and premature placental ageing in the pathophysiology of pregnancy complications. K E Y W O R D Sintrauterine growth restriction, oxidative stress, placental ageing, pre-eclampsia, preterm birth, senescence, stillbirth | INTRODUCTIONAll living organisms have limited life cycles, and ageing is part of that life cycle. Each organ within an organism also exhibits ageing-related changes; the placenta is no exception. The placenta, a specialized organ formed during pregnancy, grows throughout gestation, performs multiple functions, including endocrine regulation and nourishment of the foetus, 1 but also ages and is discarded at the end of pregnancy, while the foetus may live for another hundred years. So placental ageing is a normal physiologic phenomenon. 2 However, there are likely to be some placentas which show signs of ageing earlier than others, in the same way as some individuals age more quickly than others. Premature ageing and degenerative changes in the placenta may reduce the functional capacity of the placenta and lead to abnormal pregnancy outcomes. The placenta is the primary organ for transferring nutrients from the mother to the foetus, so growth and function of the placenta are precisely regulated and coordinated to ensure the optimal growth and development of the foetus. The placenta exchanges nutrients, for example oxygen, amino acids, carbohydrates, minerals and waste products, for example carbon dioxide between the maternal and foetal circulatory systems. 3 It releases hormones into both the maternal and foetal circulations to affect uterine function, maternal metabolism, foetal growth and development. Moreover, it metabolizes some substances and can release metabolic products into both foetal and maternal circulations. The placenta can help to protect the foetus against certain xenobiotic molecules, infections and maternal diseases. Therefore, the adequate function of this organ is crucial for a normal physiologic gestational process and a healthy baby as a final outcome.In this review, we focus on the role of OS in the pathophysiology of pregnancy complications, beginning with a brief overview of placental development at different stages of gestation. We then discuss the biochemical markers of ageing and OS-induced placental ageing.Finally, we disc...

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Raynaud's phenomenon, which is characterized by intense cold-induced constriction of cutaneous arteries, is more common in women compared with men. Cold-induced constriction is mediated in part by enhanced activity of alpha(2C)-adrenoceptors (alpha(2C)-ARs) located on vascular smooth muscle cells (VSMs). Experiments were therefore performed to determine whether 17beta-estradiol regulates alpha(2C)-AR expression and function in cutaneous VSMs. 17beta-Estradiol (0.01-10 nmol/l) increased expression of the alpha(2C)-AR protein and the activity of the alpha(2C)-AR gene promoter in human cultured dermal VSMs, which was assessed following transient transfection of the cells with a promoter-reporter construct. The effect of 17beta-estradiol was associated with increased accumulation of cAMP and activation of the cAMP-responsive Rap2 GTP-binding protein. Transient transfection of VSMs with a dominant-negative mutant of Rap2 inhibited the 17beta-estradiol-induced activation of the alpha(2C)-AR gene promoter, whereas a constitutively active mutant of Rap2 increased alpha(2C)-AR promoter activity. The effects of 17beta-estradiol were inhibited by the estrogen receptor (ER) antagonist, ICI-182780 (1 micromol/l), and were mimicked by a cell-impermeable form of the hormone (estrogen:BSA) or by the selective ER-alpha receptor agonist 4,4',4'''-(4-propyl-[(1)H]-pyrazole-1,3,5-triyl)tris-phenol (PPT; 10 nmol/l) or the selective ER-beta receptor agonist 2,3-bis(4-hydroxyphenyl)-propionitrile (DPN; 10 nmol/l). Therefore, 17beta-estradiol increased expression of alpha(2C)-ARs by interacting with cell surface receptors to cause a cAMP/Rap2-dependent increase in alpha(2C)-AR transcription. In mouse tail arteries, 17beta-estradiol (10 nmol/l) increased alpha(2C)-AR expression and selectively increased the cold-induced amplification of alpha(2)-AR constriction, which is mediated by alpha(2C)-ARs. An estrogen-dependent increase in expression of cold-sensitive alpha(2C)-ARs may contribute to the increased activity of cold-induced vasoconstriction under estrogen-replete conditions.

The placenta ages as pregnancy advances, yet its continued function is required for a successful pregnancy outcome. Placental aging is a physiological phenomenon; however, there are some placentas that show signs of aging earlier than others. Premature placental senescence and aging are implicated in a number of adverse pregnancy outcomes, including fetal growth restriction, preeclampsia, spontaneous preterm birth, and intrauterine fetal death. Here we discuss cellular senescence, a state of terminal proliferation arrest, and how senescence is regulated. We also explore the role of physiological placental senescence and how aberrant placental senescence alters placental function, contributing to the pathophysiology of fetal growth restriction, preeclampsia, spontaneous preterm labor/birth, and unexplained fetal death.