Porcine Relaxin Affects the Release of Luteinizing Hormone in Rats

Summerlee, A. J. S.; Mumford, Andrew D; Smith, M. Susan

doi:10.1111/j.1365-2826.1991.tb00254.x

Cited by 14 publications

(9 citation statements)

References 18 publications

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“…We have also shown that the dipsogenic actions of porcine relaxin in conscious rats require an intact brain angiotensin-11 system: central blockade with saralasin completely inhibits relaxin-induced drinking behavior (52). Finally, the action of relaxin on luteinizing hormone release in conscious rats is blocked by saralasin pre-treatment (60).…”

Section: Relaxin and The Forebrain Angiotensin-ll Systemmentioning

confidence: 95%

The Emerging Concept of Relaxn as a Centrally Actng Peptide Hormone with Hemodynamic Actions

Geddes

Summerlee

1995

J Neuroendocrinology

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The novel finding that relaxin has an action on the brain was first published in 1984. Since then, it has been shown that exogenous relaxin affects the release of a number of hypothalamo-pituitary hormones and has a robust pressor action. In this paper, we review the accumulating evidence that relaxin affects the release of oxytocin and vasopressin by an action at the level of the brain. The potential mechanisms of this central action are discussed and the evidence presented for the interaction between relaxin and the forebrain angiotensin-ll system. Furthermore, we articulate the possible physiological influences of relaxin on the changes in cardiovascular function that occur during pregnancy.F. L. Hisaw ( I ) discovered an ovarian substance that caused relaxation of the pelvic ligament of a variety of species in 1926 but it was not until 1930 that the first crude extract of the substance was obtained and named relaxin (2). Initial work focused on the role of relaxin on the birth canal and it was not until 1957 that an effect on the cardiovascular system was first reported (3). Miller and colleagues (3) showed that an extract of ovary caused a short hypotensive episode in dogs and suggested that relaxin had a direct action on peripheral blood vessels. Since that time. a number of hemodynamic actions of relaxin have been described (4, 5). The balance of the data, however, suggests that relaxin is hypertensive and exerts this effect through an action at the level of the brain (6-9) and on the heart (10, 11). RelaxinRelaxin is a peptide hormone produced primarily by the corpus luteum, placenta, uterus and possibly brain. It is present in detectable quantities in the peripheral circulation only during pregnancy. There are considerable species differences in the site and pattern of release of the hormone, hormone structure, and the putative role the hormone plays in the preparturient period. These differences have been extensively reviewed by Sherwood (4). Most research into the physiological actions of relaxin has been carried out using porcine relaxin obtained by the method described by Sherwood and O'Byrne (12). The classic actions of relaxin in pregnancy include softening of the cervix (13), separation of the pelvic symphysis (14). and maintenance of myornetrial quiescence towards the end of pregnancy ( 15).In the rat, relaxin is produced almost entirely within the corpora lutea of pregnancy (16) although there is some evidence that the hormone may also be produced by the endometrium (17). Levels of hormone are below the limit of detectability, by radioimmunoassay. during the first 7/12 days of pregnancy and start to increase from day 7 onwards. The levels increase steadily until day 16 when they begin to plateau. In the 48 h before birth, in association with the collapse of the corpora lutea, relaxin levels show a sharp peak then fall to low levels before birth starts (18). Sherwood et al. (18) also reported that there were peaks of relaxin in parturition. Although these data have not been confirmed by ...

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Section: Relaxin and The Forebrain Angiotensin-ll Systemmentioning

confidence: 95%

The Emerging Concept of Relaxn as a Centrally Actng Peptide Hormone with Hemodynamic Actions

Geddes

Summerlee

1995

J Neuroendocrinology

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“…Measurements of relaxin in ovarian cycles and throughout pregnancy indicate, in agreement with histological studies, that the ovary and uterus produce relaxin in a manner that is dependent upon steroid hormone and/or gonadotrophin secretion, and that pituitary-ovarian-uterine feedback mechanisms may exist [48,54,55]. Because the corpus luteum and preplacental endometrium are important regulators of early implantation in natural conceptive cycles the functional regulation of relaxin secretion in these tissues will be discussed but will be limited to a summary of the effects of steroid hormones and gonadotrophins.…”

Section: Ovarian Relaxin Secretion and Functional Regulationmentioning

confidence: 64%

Biology of primate relaxin: A paracrine signal in early pregnancy?

Hayes

2004

Reprod Biol Endocrinol

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Relaxin is a peptide hormone that exerts numerous effects in a variety of tissues across a broad range of species. Although first identified more than 75 years ago interest in relaxin biology has waxed and waned over the years consistent with peaks and troughs of new experimental data on its wide-ranging biological effects and advances in relaxin enabling technologies. Recent insights into species-dependent differences in relaxin biology during pregnancy have once again stimulated a relative surge of interest in the study of relaxin's reproductive biology. Identification and pharmacological characterization of orphaned relaxin receptors and exploration of its paracrine effects on pregnancy using genomic and proteomic technologies have succeeded in fueling current interest in relaxin research. Primates and non-primate vertebrates exhibit very disparate profiles of relaxin genomics, proteomics and functional biology. Non-human primates appear to exhibit a very close similarity to humans with respect to relaxin reproductive biology but the similarities and subtle differences are only just beginning to be understood. We, and others, have shown that relaxin produces significant changes to the non-human primate endometrium during the peri-implantation period that are consistent with relaxin's long perceived role as a paracrine modulator of pregnancy. The purpose of this review is to summarize the reproductive biology of relaxin in non-human primates with a specific emphasis on the paracrine role of ovarian and endometrial relaxin during embryo implantation and early pregnancy.

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“…Relaxin has also been found to affect the hormones of the anterior pituitary gland, where it promotes prolactin secretion in rats and monkey [95], enhances secretion of growth hormone in monkeys [111], and inhibits release of luteinizing hormone in rats [112]. The presence of relaxin-3 and both LGR7 and GPCR135 in the nucleus incertus have led to speculation that relaxin-3 may have a role in regulating the level of behavioural activation, influencing attention, motivation, locomotion, and learning [86,92].…”

Section: Other Effects Of Relaxin Peptides In the Brainmentioning

confidence: 99%

Actions of Relaxin on Non-Reproductive Tissues

Samuel

Mookerjee

Lekgabe

2005

CMCIEMA

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Initially thought of as primarily a reproductive hormone, relaxin is emerging as a multi-functional factor in a broad range of target tissues including the cardiovascular, renal, and respiratory systems, in addition to the brain, skin, liver and other less studied organs. The ever-increasing detection of H2/relaxin and the newly discovered H3/relaxin-3 gene transcripts and/or immunostaining in several non-reproductive organs suggests that these tissues may act as nonovarian sources of relaxin production in numerous mammalian species. Furthermore, the recent discovery that the relaxin receptor was identified as an orphan leucine-rich repeat containing G-protein coupled receptor-7 (LGR7), and subsequent detection of LGR7 expression in several non-reproductive tissues have confirmed these organs as targets for relaxin binding and activity. This review, discusses evidence from several studies that collectively demonstrate the many diverse and vital roles that relaxin plays in male and non-pregnant female mammals, each with significant therapeutic and clinical implications. Relaxin has been reported to decrease extracellular matrix turnover, when stimulated by chemical, surgical and genetic means, in addition to organ scarring (fibrosis) in the heart, lung, kidney, liver and skin. Relaxin also protects many non-reproductive organs through its ability to promote vasodilation of the vasculature, angiogenesis and wound healing, while counteracting allergic reactions via its anti-inflammatory actions. Furthermore, the identification of relaxin peptides and receptors in numerous regions of the brain, involved in a range of sensory and autonomic functions has expanded the biological significance of the relaxin peptide family.

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Porcine Relaxin Affects the Release of Luteinizing Hormone in Rats

Cited by 14 publications

References 18 publications

The Emerging Concept of Relaxn as a Centrally Actng Peptide Hormone with Hemodynamic Actions

The Emerging Concept of Relaxn as a Centrally Actng Peptide Hormone with Hemodynamic Actions

Biology of primate relaxin: A paracrine signal in early pregnancy?

Actions of Relaxin on Non-Reproductive Tissues

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