Immunoreactive Relaxin Research Articles

Immunoreactive relaxin in the peritoneal fluid during spontaneous menstrual cycle in women.

Annals of the New York Academy of SciencesVolume 380, Issue 1 p. 126-130 IMMUNOREACTIVE RELAXIN IN THE PERITONEAL FLUID DURING SPONTANEOUS MENSTRUAL CYCLE IN WOMEN*,† K. Thomas, K. Thomas Physiology of Human Reproduction Research Unit Department of Obstetrics and Gynecology University of Louvain B-1200 Brussels, BelgiumSearch for more papers by this authorE. Loumaye, E. Loumaye Physiology of Human Reproduction Research Unit Department of Obstetrics and Gynecology University of Louvain B-1200 Brussels, BelgiumSearch for more papers by this authorJ. Donnez, J. Donnez Physiology of Human Reproduction Research Unit Department of Obstetrics and Gynecology University of Louvain B-1200 Brussels, BelgiumSearch for more papers by this author K. Thomas, K. Thomas Physiology of Human Reproduction Research Unit Department of Obstetrics and Gynecology University of Louvain B-1200 Brussels, BelgiumSearch for more papers by this authorE. Loumaye, E. Loumaye Physiology of Human Reproduction Research Unit Department of Obstetrics and Gynecology University of Louvain B-1200 Brussels, BelgiumSearch for more papers by this authorJ. Donnez, J. Donnez Physiology of Human Reproduction Research Unit Department of Obstetrics and Gynecology University of Louvain B-1200 Brussels, BelgiumSearch for more papers by this author First published: January 1982 https://doi.org/10.1111/j.1749-6632.1982.tb18035.xCitations: 3 * This work was supported by Grant 3.45.56–9 from the Fonds de la Recherche Scientifique Médicale, Belgium. † Contributed paper. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume380, Issue1Relaxin: Structure, Function, and EvolutionJanuary 1982Pages 126-130 RelatedInformation

Placental control of ovarian immunoreactive relaxin secretion in the pregnant rat.

To investigate the control mechanisms for the secretion of relaxin in pregnant rats, the effects of the fetus, placenta, and uterus were studied. Plasma immunoreactive relaxin and progesterone were measured in pregnant rats, from days 8--1 post partum. On day 16 of pregnancy, groups of animals were subjected to removal of the fetuses, conceptuses (fetuses and placentae), or uteri. To determine whether there are extraovarian sources of circulating relaxin, a group of pregnant rats was ovariectomized on day 16. Immunoreactive relaxin was undetectable in the plasma of pregnant rats before day 10, and increased to a mean concentration of 0.52 +/- 0.01 (SEM) ng/ml on day 13. In control animals, immunoreactive relaxin levels remained at about this concentration throughout the remainder of pregnancy and declined rapidly post partum. The pattern of secretion of relaxin in fetectomized animals was similar to that in controls. In contrast, a significant decline in immunoreactive relaxin was seen, within 24 h after surgery, in those animals in which removal of the conceptuses or hysterectomy was performed. In these animals, immunoreactive relaxin was undetectable within 48 h after surgery and remained undetectable throughout the experimental period. In animals that were ovariectomized, immunoreactive relaxin was undetectable 24 h after surgery. Progesterone secretion in animals that had fetectomy or removal of the conceptuses performed was similar to that in controls. These groups showed a significant decline in progesterone on day 17 of pregnancy, and progesterone continued to decline until day 1 post partum. Progesterone in hysterectomized animals declined more abruptly than in either controls or other experimental groups. Ovariectomy resulted in a prompt fall in plasma progesterone. These results indicate that in the rat, the fetus is not needed for the maintenance of relaxin secretion throughout pregnancy, the placenta controls the ovarian secretion of relaxin. The uterus does not exert a tropic effect upon relaxin secretion, no extraovarian sources of circulating relaxin exist in the rat, and there is a divergence between progesterone and relaxin secretion during rat pregnancy.

Relaxin immunoactivity in plasma during the reproductive cycle of the female guinea pig.

Plasma relaxin immunoactivity was measured in guinea pigs during the estrous cycle from midpregnancy to parturition as well as during acute suckling using a homologous porcine relaxin radioimmunoassay. Samples were collected at frequent intervals from an indwelling jugular vein catheter. The peak levels found during pregnancy, ∿12 ng/ml, were higher than the peak levels during the estrous cycle and suckling (4–5 ng/ml). During the estrous cycle, relaxin levels were low at estrus and early diestrus and were high at late diestrus and proestrus preceeding the opening of the vaginal membrane. During late pregnancy, episodic secretion of immunoreactive relaxin was common and the timing of this secretion varied. In some guinea pigs, relaxin levels increased in mid to late pregnancy; others showed only a rise before parturition or only the mid to late pregnancy rise. Spectral analysis of the data revealed clear periodicities in the results from several animals but others showed no evidence of periodicity. The most common period was 18 h. In most animals, but not all, the onset of lengthening of the pubic ligament as determined by palpation was preceded by a period of relaxin production. There was no evidence for an acute effect of suckling to elevate relaxin secretion in this species; indeed suckling decreased relaxin immunoactivity with mean levels of control animals significantly higher than those of animals suckling their young.

Relaxin Production by the Porcine Ovarian Graafian Follicle in vitro

Immunoreactive rela.xin was shown to be present in pools of porcine follicular fluid collected from individual ovaries from cyclic and pregnant sows. In the cyclic animals, the highest relaxin level was obtained from ovaries containing active corpora lutes, but at no stage during the cycle did relaxin content of follicular fluid approach that found in ovaries of pregnant sows. Fractionation of follicular fluid on Sephadex C-SO revealed at least three immunoreactive relaxin peaks of differing molecular weight: >40,000, 20,000, and one corresponding to authentic relaxin (6300). Serum of pregnant sows when fractionated in a similar fashion contained more of the highest molecular weight immunoreactive relaxin while only ‘\‘20% of the immunoreactivity was associated with 6300 relaxin. Isolated ovarian follicles and follicular tissue released relaxin throughout prolonged periods in culture. Relaxin output in vitro was significantly higher for tissue obtained from pregnant than from nonpregnant sows. Examination of the relationship between steroid hormone and relaxin release revealed that follicle wall segments, washed free of follicular fluid, released both more relaxin and steroids than did intact follicles. Of the steroids examined, the pattern of relaxin most resembled that found for progesterone, which showed an increase after 48 h of culture as the tissue underwent spontaneous luteinization. The relationship between steroid hormone and relaxin biosynthesis was further studied in these cultures by the addition of inhibitors of steroid biosynthesis. Aminoglutethimide effectively reduced production of all steroids studied without significantly reducing the total production of relaxin over the culture period. Tniostane and androstriene 3, 17-dione were only partially effective in reducing steroidogenesis but caused a significant reduction in total relaxin production. Follicular tissue therefore synthesizes and secretes relaxin in vitro, but the cellular origin, the relationship with steroidogenesis, and the routes of release remain to be established.

Induction of relaxin secretion in nonpregnant women by human chorionic gonadotropin.

Five normal women using barrier forms of contraception has serum samples drawn every 2 days during control menstrual cycles. Relaxin was not detectable in their serum. All five subjects then received 2500 IU hCG im every 2 days beginning 8--10 days after presumed ovulation. All had immunoreactive relaxin detectable in serum 2--6 days after the first hCG injection. Relaxin rose to pregnancy levels (range, 0.26--0.62 ng/ml; mean, 0.38 +/- 0.17 ng/ml) by cycle day 31 and then declined before menstruation. Progesterone levels and cycle lengths of relaxin-secreting cycles were significantly higher (P less than 0.05) than control cycles. Three of the five subjects subsequently received 2500 IU hCG im every 2 days commencing 2--3 days after presumed ovulation until menstruation. Relaxin was not detectable in these cycles. hCG can induce relaxin secretion in nonpregnant women. A hCG stimulus which can induce relaxin secretion from an 8- to 10-day-old corpus luteum cannot induce relaxin secretion in a 2- to 3-day-old corpus luteum, suggesting that the age of the human corpus luteum of the menstrual cycle is an important determinant of responsiveness to hCG.

Immunoreactive relaxin-like substance in human seminal plasma.

Large amounts of an immunoreactive relaxin-like peptide were demonstrated in human seminal plasma. The concentrations of this peptide were determined in seven healthy volunteers, and in twenty-eight non-selected male patients seeking advice for sterility. A wide range of immunoreactive relaxin concentrations was observed, varying between 1,240 pg and 73,000 pg of relaxin porcine equivalents per ml of seminal plasma. Given the very special assay medium of seminal plasma, particular attention was paid to the validity of the radioimmunoassay system when applied to this medium.

Serum immunoreactive relaxin concentrations in human pregnancy, labor and the puerperium.

Relaxin is a peptide hormone of pregnancy which plays a role in pregnancy maintenance and parturition in several mammalian species (1). Immunoassayable relaxin is present in women during pregnancy. Relaxin is produced solely by the human corpus luteum of pregnancy. The placenta does not directly contribute to its production (2). Relaxin extracted from the human corpus luteum of pregnancy is active in the guinea pig pubic symphysis palpation assay. The biological activity paralleled the immunoactivity of these extracts (3). The purpose of this study is to determine secretion patterns of relaxin at various times during normal pregnancies.

Serum relaxin levels in prostaglandin E 2 induced abortions

Relaxin, a peptide hormone produced only by the corpus luteum of pregnancy, can be used as a marker of luteal function in human pregnancy. Serum immunoreactive relaxin levels were measured serially in six women having second trimester abortions induced with intravaginal prostaglandin E2 (PGE 2) suppositories. All patients aborted within 17 hours of the first suppository. No significant changes were detectable in serum relaxin levels in any of the patients. It is concluded that PGE 2 does not interfere with the corpus luteum's ability to secrete relaxin in the second trimester of human pregnancy.

Plasma Immunoreactive Relaxin Levels in Pregnant and Nonpregnant Women

Immunoreactive relaxin was measured in plasma samples obtained from human volunteers utilizing the RIA procedure of Sherwood et al., as modified by O'Byrne and Steinetz for heterologous plasma samples. Immunoreactive hormone was not detected in samples obtained from men, and only rarely in plasma of nonpregnant women. Immunoreactive relaxin was present as early as the fourth week of pregnancy and was detectable throughout the course of gestation. Immunoreactive relaxin tended to be higher early in pregnancy, and there was no peak just before parturition as occurs in many other species. Our results are at variance with those of Bryant and coworkers, who reported high levels of immunoreactive relaxin in men and nonpregnant as well as pregnant women. The possible reasons for this discrepancy are presented.

Characterization of relaxin radioimmunoassay using Bolton-Hunter reagent. First results in plasma during pregnancy, and in placenta, corpora lutea and ovarian cysts in woman.

Application of a porcine relaxin radioimmunoassay system using Bolton and Hunter reagent was characterized in different biological fluids. In pregnant woman, plasma reveals concentrations from undetectable values to 1,800 pg/ml. Maximal concentrations are found between the 8th and the 13th weeks of pregnancy. These peak values are significantly different from those at other stages of pregnancy. Appreciable relaxin concentrations are detected in gestational corpus luteum extract, and in corpora lutea cyst fluid of pregnant and nonpregnant women. No relaxin was detected in a cyclus corpus luteum extract, in a placental extract, or in an ovarian serous cyst. The presence of immunoreactive relaxin in the nonpregnant woman is reported.

Serum immunoreactive relaxin and softening of the uterine cervix in pregnant hamsters.

Serum immunoreactive relaxin levels and ripening of the cervix were measured throughout pregnancy in hamsters. RIA relaxin rose from an undetectable level on day 7 to a maximum value of 29 ng/ml on day 15 of gestation and then fell prior to parturition. The cervix became progressively more dilatable from the 12th to the 16th day of pregnancy. It is suggested that the endogenous relaxin measured by RIA may induce the cervical softening. The absolute levels of immunoreactive relaxin appear to be 10 to 15-fold higher than those previously observed in rats, mice and guinea pigs.

Immunoreactive relaxin in human serum during the menstrual cycle.

Immunoreactive relaxin was measured in serum obtained at the same time each day from one woman during a normal menstrual cycle and eight other women using selected bleeding schedules. In addition to relaxin immunoactivity, serum luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin, estradiol 17beta, and progesterone were measured in the same samples. The data was combined according to the day of the LH peak. Serum relaxin immunoactivity was found to be high over the period of menstruation, its concentration then decreased until the middle of the follicular phase when a peak equal in amplitude to the menstrual peak occurred. Relaxin immunoactivity remained fairly constant throughout the preovulatory LH surge; however, as the LH levels dropped, relaxin immunoactivity increased reaching maximal levels for the whole cycle. Relaxin immunoactivity then increased gradually over the luteal phase and reached a peak when progesterone levels were declining; it then dropped to low levels until menses ensued. It is not possible with the present radioimmunoassay to determine whether the immunoactive relaxin was ovarian or uterine in origin.