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Clinical Endocrinology of Pregnant Mares
Published in Juan Carlos Gardón, Katy Satué, Biotechnologies Applied to Animal Reproduction, 2020
Finally, relaxin is produced by the trophoblastic cells of the placenta (Klonisch and Hombach-Klonisch, 2000) and its activity is related to myometrial (Ousey, 2006), as well as of the cervix and pelvic ligaments relaxation (Bryant-Greenwood, 1982). Maternal plasma levels increase at the end of gestation (4–7 ng/mL) and during the second labor stage (11 ng/mL). After the expulsion of the placenta, it returns to basal values below the detection limit at 36 h (Stewart et al., 1982a), remaining elevated in cases of placental retention. However, important variations associated with breed have been described, a fact that does not seem to be related to the placental size or sex of the offspring (Stewart et al. 1992). The functional significance of these differences in terms of actions of relaxin is unknown.
Pregnancy-Related Proteins Detected by Their Biological Activities
Published in Gábor N. Than, Hans Bohn, Dénes G. Szabó, Advances in Pregnancy-Related Protein Research, 2020
Relaxin is a female sex hormone related in structure to insulin.44 It seems to have an important role in the regulation of physiological and biochemical processes in the reproductive tract during pregnancy and parturition.45 In women, the corpus luteum seems to be the main source of relaxin.46,47 In addition, relaxin was also found to occur in human placenta. It is suggested that the placental relaxin may bring about the separation of the placenta from the uterus at parturition.48
Pharmacological Strategies for Uterine Relaxation
Published in Robert E. Garfield, Thomas N. Tabb, Control of Uterine Contractility, 2019
Michael Hollingsworth, Sandra J. Downing, Josephine M. S. Cheuk, Ian T. Piper, Sarah J. Hughes
Relaxin is a polypeptide hormone of about 6.5-kDa molecular weight that is synthesized in and secreted from the corpus luteum, placenta, or myometrium during pregnancy.46 The physiological functions of relaxin include myometrial relaxation as well as softening of the cervix and ligaments of the pelvic girdle, facilitation of parturition, and aiding mammary growth.46,47,47a
Can maternal hormones play a significant role in delivery mode?
Published in Journal of Obstetrics and Gynaecology, 2022
Christina Pappa, Fani Gkrozou, Evangelos Dimitriou, Orestis Tsonis, Aikaterini Kitsouli, Dimitrios Varvarousis, Vasileios Xydis, Minas Paschopoulos, Panagiotis Kitsoulis
Data deriving from studies conducted to human tissues reveal that progesterone, oestradiol and relaxin receptors are present on ligaments, cartilages, muscles and tendons. Those hormones can pose their action through their binding to the receptors by altering the constitution of the target tissues (Park et al. 2005; Goldsmith and Weiss 2009; Chidi-Ogbolu and Baar 2018). Progesterone is known to augment fibroblast proliferation and thus to increase collagen formation, while oestradiol has the adverse effect. Relaxin is known to reduce the tendons stiffness and increase laxity through activating the collagenase. Furthermore, by activating the collagenolytic system through releasing MMPs (MMP-1, MMP-3), collagenase and plasminogen activator, relaxin finally degrades the extracellular matrix composition, softens and relaxes ligaments and cartilages (Qin et al. 1997; Goldsmith and Weiss 2009). In muscles, relaxin is regulating inflammatory response, tissue remodelling and fibrosis (Romani et al. 2003). Relaxin and oestradiol are believed to act in synergy causing tissue relaxation, while progesterone is known to pose an opposite action on cartilaginous, ligamentous and tendinous tissues (Romani et al. 2003; Hashem et al. 2006).
Ocular Phenotype of Relaxin Gene Knockout (Rln-/-) Mice
Published in Current Eye Research, 2020
Ulrike Hampel, Holly R. Chinnery, Fabian Garreis, Friedrich Paulsen, Robb de Iongh, Bang V. Bui, Christine Nguyen, Laura Parry, Chen Huei Leo
The relaxin peptide family, including relaxin and insulin-like peptide 3 (INSL3) are endogenous peptides that are structurally related to insulin. Humans and higher primates have two relaxin (RLN1 and RLN2) genes, whereas other mammals only have RLN1.1 The circulating relaxin peptide (referred to herein as relaxin, RLN), originally detected during pregnancy, is encoded by RLN2 in humans, and by RLN1 in other mammals, including rodents.2 Many animal studies have characterized the biological action of relaxin as a pregnancy hormone. Specifically, it is well known that RLN contributes to some of the key maternal cardiovascular and renal adaptations during pregnancy.3,4 For example, RLN can influence the expression of aquaporins, water channels that regulate the hydration of tissue not just those found in the cervix or kidney but also in the eye.5
The ART of frozen embryo transfer: back to nature!
Published in Gynecological Endocrinology, 2020
Barbara Lawrenz, Carol Coughlan, Laura Melado, Human M. Fatemi
The crucial step for successful implantation is to achieve synchrony between the endometrium and the embryo developmental stage. Recently, published data formulate the hypothesis that the ‘easier’ and more straightforward approach with suppression of the endogenous cycle by the administration of exogenous hormones may result in an increased risk of hypertensive disorders in pregnancy due to the absence of the CL and relaxin. Relaxin is one of the vasodilatory reproductive hormones of pregnancy [66]. As a consequence of the CL absence, adapatation of the maternal circulatory system during early pregnancy may be impaired and may result in adverse pregnancy outcomes, including preeclampsia [14]. To avoid the administration of exogenous estrogens and progesterone, in women with regular ovulatory cycles, endometrial preparation through rising estradiol levels from a growing follicle in a natural cycle, spontaneous LH-surge and development of a CL can be discussed as the preferred approach. However, it has to be kept in mind, that there is no available data examining these outcomes in NC-FET. Therefore, further appropriately conducted randomized controlled trials of the natural cycle are urgently warranted to confirm that NC-FET is not inferior to HRT-FET and may even be advantageous to both, the mother and baby.