Relaxin Concentrations Research Articles

220 Litter performance, serum collagen, and hormone concentrations in prolapsed and non-prolapsed sows

Abstract Pelvic organ prolapse is one of the top leading causes of sow mortality today and widely considered a multifactorial issue. Previous reports observed prolapsed sows having decreased serum concentrations of various trace minerals and increased tumor necrosis factor-alpha compared with non-prolapsed sows. Additionally, collagen, hormones, and previous litter performance are other factors proposed to be associated with POP. A study was completed to determine differences in serum collagen type 1 (COL1), matrix metalloproteinase 1 (MMP-1), tissue inhibitor of metalloproteinase 1 (TIMP-1), as well as relaxin and estradiol differences in the serum concentration between prolapsed and non-prolapsed sows. Furthermore, previous litter performance, lactation days, pigs born, stillborns, mummified, and pigs weaned on prolapse rate were evaluated. The study utilized 44 prolapsed sows and 44 non-prolapsed sows of similar parity, location, management, and stage of production. Blood was collected from the prolapsed and non-prolapsed sows upon discovery. Serum samples were analyzed using radioimmunoassay for estradiol content. Additionally, COL1, MMP-1, TIMP-1, and relaxin concentrations were determined from the serum using ELISA testing. Data were analyzed using the PROC GLIMMIX procedure in SAS. Prolapsed sows had decreased (P < 0.05) COL1 and TIMP-1 concentrations in the serum compared with the non-prolapsed sows. Prolapsed sows had marginally greater (P < 0.10) MMP-1 concentration compared with non-prolapsed sows. There were no differences (P > 0.10) between prolapsed and non-prolapsed serum concentraions of sows for estradiol and relaxin. Prolapsed sows had longer lactation days (P < 0.05) in the litter before prolapsing compared with non-prolapsed sows. Additionally, stillborns in the previous litter were marginally greater (P = 0.06) in prolapsed sows when compared with the non-prolapsed sows. There were no differences (P > 0.10) in pigs born, mummified, or pigs weaned between prolapsed and non-prolapsed sows. This study suggests that there is a reduced concentration of serum COL1 and TIMP-1 found in prolapsed sows compared with non-prolapsed sows and a marginally increased MMP-1 concentration in prolapsed sows. This could influence the structural integrity of the connective tissue that supports the pelvic organs. We found no differences in serum estradiol or relaxin levels. Additionally, lactation days and stillborn pigs in the litter prior to prolapsing could be contributing factors to prolapse. This work further supports the idea that prolapse is a multifactorial issue.

Plasma relaxin, estrogens and progestogens concentration in coldblooded and hot-blood mares in the second half of gestation

Monitoring estrogens, progestogens, and relaxin plasma concentration can be important for determining pregnancies at risk of failure in mares. However, significant breed-related differences in values of reproductive hormones are known, and data concerning coldblooded (CB) mares are missing. The aim of the study was to determine and compare serum relaxin, estrone sulphate (E1S), estradiol-17β (E2), and progestogens concentration in pregnant CB and hot-blood (HB) mares during the second half of gestation. Blood samples obtained from 94 healthy mares in the second half of gestation with known mating dates were analyzed. Samples were collected from 36 CB mares aged from 3 to 16 years and 58 HB mares aged from 4 to 17 years. The hormone concentrations were measured using immunoenzymatic equine species-specific commercial kits. The serum relaxin concentration was almost three times lower in CB, whereas E1S and E2 almost twice as low, as compared to HB mares (P < 0.05). In conclusion, the extremely low concentration of relaxin in CB mares could be one reason for the increased amounts of difficult parturition requiring veterinary intervention noted in these breeds.

Greater presence of receptors for relaxin in the ligamentum teres of female infants who undergo open reduction for developmental dysplasia of the hip

BackgroundWhile many factors involved in the etiology of developmental dysplasia of the hip (DDH), one of which is the hormone relaxin. Relaxin concentrations in patients with DDH may lead to pathodynamic changes during hip development by altering the physiological nature of the ligament, as well as by long-term exposure to relaxin during pregnancy. Our objective in this study was to determine the number of relaxin receptors in the ligamentum teres and their role in causing DDH.MethodsWe identified 26 infants between birth and 3 years of age who had undergone open reduction for DDH between 2010 and 2012. 12 hips of 12 miss abortus fetus between 20 to 35 weeks of gestation were used as control group. Specimens obtained from two groups were stained with Relaxin-2 antibody, and the amount of staining for relaxin receptors was determined using an ordinal H score.ResultsThe mean (SD) H scores of infants with DDH were significantly higher than those of controls: 215 (59) versus 52 (48); P = 0.00; 95% CI. Statistically significant difference between the two groups in terms of gender was not found.ConclusionAs a result, increased number of relaxin receptors in the ligamentum teres could be a risk factor for DDH.Level of evidenceLevel 2, Prospective comparative study.

Association between the Area of the Highest Flank Temperature and Concentrations of Reproductive Hormones during Pregnancy in Polish Konik Horses-A Preliminary Study.

Simple SummaryThermographic imaging is a potentially useful tool in pregnancy detection in equids, especially native or wildlife breeds. In late gestation, the differences in temperature of the flank area between pregnant and non-pregnant mares were suspected to be caused by hormonal effects on regional blood flow. This preliminary study aimed to assess changes in thermal features of the abdomen lateral surface and concentrations of reproductive hormones in Polish native pregnant mares. The study was carried out on pregnant and non-pregnant Polish native Konik Polski mares, and both the hormonal profile and the thermal pattern of mares’ abdomens were examined monthly. The features from thermal images in rainbow HC and gray palette were extracted to determine relations with a hormonal profile dependent across the months of pregnancy. The new feature of a thermal image in the gray palette, the area with the highest temperatures (Area of Tmax), was found to be significantly related to progesterone and relaxin blood concentration. The standard features of the thermal image did not show any similar associations over consecutive months of pregnancy. In this preliminary study, a new approach to thermographic imaging analysis based on the Area of Tmax calculation was proposed. However, further research is needed to better understand the relation between the Area of Tmax and concentrations of reproductive hormones, especially including an experiment with at least daily blood sampling and the hair coat lengths examination.Determination of the pregnancy status is one of the most important factors for effective pregnancy management. Knowledge of the stage of pregnancy is important to interpret many of the reproductive hormones’ concentrations, including progesterone (P4), estrone sulfate (E1S), 17-ß estradiol (E2), and relaxin (REL). However, it is limited in wildlife or captive equids that cannot be handled. Reproductive hormones affect regional blood flow, the proliferation of tissues, and local metabolism intensity. Therefore, this preliminary study aimed to assess changes in thermal features of the abdomen lateral surface and concentrations of reproductive hormones in Polish native pregnant mares. The study was carried out on 14 non-pregnant and 26 pregnant Polish Konik mares during eleven months of pregnancy. Infrared thermography was conducted to image the lateral surface of mares’ abdomen (Px1) and flank area (Px2); P4, E1S, E2, and REL concentrations in serum were also determined. The evidence of the association between the area with the highest temperatures (Area of Tmax) and serum concentrations of P4 (the slope = 1.373; p = 0.9245) and REL (the slope = 1.342; p = 0.4324) were noted dependent across months of pregnancy. Measures of superficial body temperatures were found to change monthly, similarly to ambient temperatures, with no evidence of coincidence with changes in reproductive hormone concentrations. Individual thermal characteristics of the lateral surface of the abdomen differed between pregnant and non-pregnant mares in other periods. Differences in maximal and average temperature and Area of Tmax were observed from the sixth month of pregnancy, and those in minimal temperature were observed from the eighth month.

Neurohumoral and biochemical markers of prolonged second stage of labor

Objective:to study the role of neurohumoral and biochemical changes in the pathogenesis of prolonged second stage of labor.Material and methods.To achieve the above objective, we examined 35 parturient women with prolonged second stage of labor and 45 parturient women with physiological labor. We studied the levels of progesterone, estradiol, relaxin, serotonin, cholesterol, thiobarbituric acid reactive substances (TBARS), total antioxidant capacity of plasma, products of final protein oxidation, as well as the total concentrations of nitrite and nitrate ions (NOx) in blood plasma.Results.In the women with prolonged second stage of labor, the levels of estradiol and progesterone were significantly higher than in those with physiological childbirth (p1 = 0.037, p2 = 0.029). The women giving birth by operation had higher estradiol (p = 0.017) and progesterone (p = 0.07) levels than those giving birth physiologically. The level of relaxin was lower in the women with prolonged second period of labor than in those with physiological labor (p = 0.084), especially in the case of operative delivery (p = 0.041), the risk of which increases 4.1 times when the relaxin concentration is less than 36.4 ng/l. Compared to the patients giving physiological childbirth, the patients with prolonged second stage of labor who delivered by cesarean section had significantly higher TBARS levels (p = 0.043). Its concentration &gt; 180.3 μmol/l increases the risk of cesarean section almost by 12 times (p = 0.003).Conclusion.The hormonal aspect of the pathogenesis of prolonged second stage of labor is characterized by higher concentrations of steroid hormones — estradiol and progesterone, as well as by a lower level of relaxin in plasma. The biochemical aspect of the pathogenesis is represented by an increased concentration of lipid peroxidation products, which can be identified with severe physical fatigue in childbirth. The detected changes can be applied in the complex diagnostics of prolonged second stage of labor.

Role of relaxin in diastasis of the pubic symphysis peripartum

BACKGROUNDSeparation of the pubic symphysis can occur during the peripartum period. Relaxin (RLX) is a hormone primarily secreted by the corpus luteum that can mediate hemodynamic changes during pregnancy as well as loosen the pelvic ligaments. However, it is unknown whether RLX is associated with peripartum pubic symphysis separation and if the association is affected by other factors.AIMTo study the association between RLX and peripartum pubic symphysis separation and evaluate other factors that might affect this association.METHODSWe performed a cross-sectional study of pregnant women between April 2019 and January 2020. Baseline demographic characteristics, including gestational age, weight, neonatal weight, delivery mode and duration of the first and second stages of labor, were recorded. The clinical symptoms were used as a screening index during pregnancy, and the patients with pubic symphysis and inguinal pain were examined by color Doppler ultrasonography to determine whether there was pubic symphysis separation. Serum RLX concentrations were evaluated 1 d after delivery using an enzyme-linked immunosorbent assay, and pubic symphysis separation was diagnosed based on postpartum X-ray examination. We used an independent-sample t test to analyze the association between serum RLX levels and peripartum pubic symphysis separation. Multivariate regression analysis was used to evaluate whether the association between RLX and peripartum pubic symphysis separation was confounded by other factors, and the association between RLX and the severity of pubic symphysis separation was also assessed. We used Pearson correlation analysis to determine the factors related to RLX levels as well as the correlation between the degree of pubic symphysis separation and activities of daily living (ADL) and pain.RESULTSA total of 54 women were enrolled in the study, with 15 exhibiting (observational group) and 39 not exhibiting (control group) peripartum pubic symphysis separation. There were no statistically significant differences in terms of maternal age, gestational age, pre-pregnancy weight, weight gain during pregnancy, delivery modes, or duration of the first or second stages of labor between the 2 groups. We did, however, note a statistically significant difference in serum RLX concentrations and neonatal weight between the observational and control groups (122.3 ± 0.7 µg/mL vs 170.4 ± 42.3 µg/mL, P < 0.05; 3676.000 ± 521.725 g vs 3379.487 ± 402.420 g, P < 0.05, respectively). Multivariate regression analyses showed that serum RLX level [odds ratio (OR): 1.022) and neonatal weight (OR: 1.002) were associated with pubic symphysis separation peripartum. The degree of separation of the pubic symphysis was negatively correlated with ADL and positively correlated with pain. There was no statistically significant association between serum RLX levels and the severity of pubic symphysis separation after adjusting for confounding factors.CONCLUSIONSerum RLX levels and neonatal weight were associated with the occurrence, but not the severity, of peripartum pubic symphysis separation.

Blood serum and follicular fluid relaxin: a pilot study of the hormone effects on ovarian function and fertilization efficiency

Hypothesis/aims of study. To date, one of the most important avenues of research in the field of reproductive medicine is the searching for new biochemical markers of oocyte quality and the prediction of the effectiveness of in vitro fertilization (IVF) protocols. The aim of this study was to assess the effect of relaxin levels in blood serum and follicular fluid on the efficiency of ovulation stimulation, fertilization, and characteristics of the embryos.&#x0D; Study design, materials and methods. This prospective randomized cohort study included 11 patients undergoing infertility treatment in a superovulation stimulation protocol using gonadotropin-releasing hormone antagonists. Age, body mass index, hormonal status, ovarian response, endometrial thickness and structure, the number and quality of oocytes and embryos, as well as fertilization efficiency were assessed. The level of relaxin in blood serum and follicular fluid samples was determined on the day of transvaginal follicle puncture using enzyme immunoassay.&#x0D; Results. A correlation between follicular fluid relaxin levels and body mass index, age, the number of oocytes, and their fertilization efficiency (p 0.05) was established. Changes in follicular fluid relaxin level were revealed depending on the gonadotropin preparations (p 0.05) and triggers of final maturation of oocytes (p 0.05). The tendency of the effect of gonadotropin doses on circulating relaxin levels, and of the hormone itself on endometrial thickness and the quality of oocytes was determined.&#x0D; Conclusion. Determination of the relaxin concentration can be considered as a promising method for predicting the result of ovarian stimulation and the efficiency of fertilization in IVF protocols.

Association of peripartum progesterone, estradiol, cortisol, PGFM and relaxin concentrations with retention of fetal membranes in crossbred dairy cows

Retention of fetal membranes (RFM) in bovines not only lowers fertility and productivity but also leads to significant economic loss to the dairy farms. The present study compared peripartum progesterone, estradiol, cortisol, Prostaglandin F2 metabolite (PGFM) and relaxin concentrations in crossbred cows with normal parturition (NP) and with RFM. Blood samples were collected from 33 dairy cows at weekly interval from 30 days prepartum till 7th day before calving, followed by every alternate days till calving and 1st and 2nd day postpartum. Significantly higher plasma cortisol concentrations was observed between day 3 prepartum and day 2 postpartum in RFM cows (n=6) compared to NP cows (n=6). Plasma estradiol level was significantly lower in RFM group than in NP group on the day of calving while progesterone concentrations did not differ between the groups. In RFM cows, PGFM level was significantly lower on day 1 and day 2 postpartum compared to NP cows. On the day of calving and on day 1 postpartum, relaxin concentration was significantly (P&lt;0.05) higher in NP cows compared to RFM cows. The ROC analysis, commonly used for development of diagnostic threshold value, revealed that cows with cortisol concentration above 7.35 ng/ml and PGFM concentration below 1,072 pg/ml on day-1 were associated with 5.99 times higher risk of RFM. It may be inferred that peripartum plasma cortisol and PGFM concentrations may be useful for identification of crossbred cows at the risk of developing RFM.

RELAXIN AND IMMUNE FACTORS AS PREDICTORS OF BIOLOGICAL PREPARATION FOR LABOUR

Introduction. Biological preparedness for childbirth plays an important role in ensuring the normal course of spontaneous labour, as well as determining the criteria for preinduction and induction of labour with obstetrics pathologies. Recent studies have shown that labour involves a complex interaction between maternal and fetal factors that contribute to cervical maturation and myometrial contraction. In its turn it prompts the search for predictors that allow early identification of pathologies and improve the prognosis. The Relaxin hormone may function as one of the aforementioned predictors due to the emerging evidence for its involvement in the pathogenesis of abortion. Studies show that Relaxin plays a key role in the adaptation of a female 51 body by targeting the cervix among other organs. Relaxin acts on the cervix by degrading extracellular matrix components through activation of proteolytic enzymes, known as matrix metalloproteinases (MMPs). Remodeling of the cervix is a combination of endocrine and immune interactions. One of the hallmarks of cervix remodeling is infiltration of leukocytes prior to labour. These tissue granulocytes become the source of proinflammatory cytokines that upregulate MMPs. Relaxin controls the local inflammatory response by modulating matrix metalloproteinases. Thus, understanding the regulatory role of Relaxin in systemic production of cytokines and its effect on neutrophils at different stages of cervical maturation is of great interest. Aim: characterise the interplay between Relaxin, cytokines and their joint role in regulation of proteolytic enzymes to establish new criteria for prognosis of cervical maturation. Materials and methods. 69 pregnant women of gestational age 38-40 weeks were examined. The examined women were divided into 3 clinical groups, depending on the degree of cervix maturity at the time of hospitalisation. The degree of cervix maturity was assessed by the EH Bishop scale. Group I consisted of 23 patients with a mature cervix (9-13 points), group II included 21 pregnant women with an immature cervix (6-8 points), group III contained 25 pregnant women with a completely immature cervix (0-5 points). The control group consisted of 15 women of gestational age 35-36 weeks, who were pregnant for the first time. Women of the control group were examined prior to the start of physiological processes of remodeling of cervical tissues before labour and displayed no signs of premature labour. Control group was compared to women from the I, II and III groups by disease history and somatic data. All pregnant women underwent standardized clinical examination and immunological testing. Serum concentration of cytokines IL-6 and TNF-α, MMP-1 and MMP-9, and Relaxin levels were determined by enzyme-linked immunosorbent assay using commercial kits. Statistical analysis of the results was performed using the program "STATISTICA-6". Statistical significance was calculated by Student's t-test. Spearman's rank correlation coefficient was determined between the obtained parameters. The differences were considered accurate with a significance level of p&lt;0.05. Results. The average age of the examined pregnant women was 25 years 7 months (18-33). All patients of the examined groups could be compared to each other by their age, genital features and menstrual function (p ≤ 0.05). The study has shown that the lowest serum concentration of Relaxin was found in women with immature or completely immature cervix, which accounted to 189.7±34.6 pg / ml and 208, 9±27.6 pg / ml, respectively. This suggests that serum concentration of Relaxin could serve as a possible predictor of biological readiness of the body for labour. Furthermore, serum Relaxin concentration can serve as a prognostic marker of the effectiveness of induction and preinduction of labour. The data presented shows that women with mature cervix display maximum levels of matrix metalloproteinases MMP9 and MMP-1. Specifically, the concentration was 1.8 times higher than in the group of women with immature cervix. Thus, maturation of the cervix uterus involves a significant increase in the concentration of matrix metalloproteinases by peripheral neutrophils with a gradual increase in their proteolytic activity. Our study showed that high serum concentrations of the proinflammatory cytokines in pregnant women with a mature cervix before labour were higher compared to women with an immature or completely immature cervix. The interplay between proinflammatory cytokines and other modulators presented here during the preparation of the body for labour was evident from the observed correlation. We observed a strong correlation between the level of Relaxin and matrix metalloproteinases (r = 0, 78), as well as positive correlation between their content and the cytokines of interest. Conclusion. The study allowed to identify the most prognostically significant molecular predictors that characterize the body's preparation for labour, which include the "birth hormone" Relaxin. Furthermore, our analysis implicates immune mechanisms in regulating cervical maturation before labour.

MODERN CONCEPTS IN REGULATORY MECHANISMS OF INDUCTION OF LABOR

In modern conditions of the development of obstetric science, one of the leading factors ensuring the reduction of maternal and perinatal morbidity and mortality is the solution of the problem of labor disorders by improving knowledge of the biological mechanisms of the birth process. The urgency of the problem of violations of labor is due to the frequency of distribution in the population, reaching 30%. The outcome of childbirth for the mother and fetus depends on the biological readiness of the woman’s body for childbirth. There is no doubt that the study of the mechanisms of preparation for physiological childbirth at the cellular-molecular level can provide important progress in this direction.The aim of research is to determine new mechanisms for regulating the preparation of a pregnant woman’s body for childbirth by studying the influence of hormonal and immunological factors on the maturation of the cervix.Materials and research methods. To achieve the goal, 80 primary pregnant women were examined at 38- 40 weeks of gestation, which, depending on the degree of ripe of the cervix upon admission to the hospital, were divided into the main and control groups. All pregnant women underwent anamnesis collection, a complete clinical and laboratory examination, regulated by the Order of the Ministry of Health of Ukraine No. 417 of 15.07.2011. The woman’s body readiness for childbirth was determined taking into account the assessment of the degree of “ripe” of the cervix using the scale proposed by E.H. Bishop. Immunological studies: the concentration of serum relaxin, the content of matrix metalloproteinases (MMP-1, MMP-9) in the peripheral blood serum were determined. The daily urinary excretion of information biochemical parameters, in particular, hydroxyproline and glycosaminoglycans, markers of collagen catabolism, was studied. The results were statistically processed on a personal computer using the STATISTICA-6 program.Research results and their discussion. The results of the study make it possible to identify the most significant factors characterizing the processes of preparing the body for childbirth, which include the “labor hormone” relaxin, as well as the immune mechanisms of regulation of the “ripe” of the cervix before childbirth. The data obtained allow us to regard relaxin as a positive regulator of the production of the main types of MMPs that affect type I collagen. Such a positive regulation of MMP-1 and MMP-9 due to increased levels of relaxin may be of unique importance for the development of remodeling processes of the connective tissue of the cervix, as evidenced by the change in the content of markers of metabolic processes in the cervix.Conclusions: Relaxin is an important factor in preparing the body of a pregnant woman for childbirth, due to the regulation of the production of proteolytic enzymes, matrix metalloproteinases, at the end of the gestational process. The investigated factors can be regarded as new markers of the onset of timely physiological labor, as well as the effectiveness of complex therapeutic measures for the induction of labor.

Circulating pregnancy hormone relaxin as a first trimester biomarker for preeclampsia.

Preeclampsia, a multi-system hypertensive disorder, is associated with perturbations in the maternal cardiovascular system during early pregnancy. The corpus luteal hormone relaxin, a potent vasodilator, may contribute to physiological circulatory changes especially in early gestation when circulating levels are highest. This study investigated whether first trimester circulating relaxin may be a suitable biomarker for the early prediction of preeclampsia. Relaxin was initially measured in first-trimester samples of women who developed late-onset preeclamptic (LO-PE; delivery≥34weeks; n=33) and uncomplicated pregnancies (n=25) in Pittsburgh, USA. Subsequently, to expand the group numbers, relaxin was measured in women who developed LO-PE (n=95), early-onset preeclamptic (EO-PE; delivery<34weeks; n=57), and uncomplicated pregnancies (n=469) in Utrecht, the Netherlands. In the Pittsburgh subjects, low relaxin levels (lowest centile: <p10) showed an adjusted odds ratio (OR) of 5.29 (95%CI 1.10-25.5) for LO-PE. In the Utrecht population, low relaxin levels (<p10) demonstrated adjusted ORs of 1.45 (95%CI 0.54-3.90) and 2.03 (95%CI 1.06-3.88) for EO-PE and LO-PE respectively, the latter increasing to an adjusted OR of 3.18 (95%CI 1.41-7.20) when newborn weight was<10%. Serum relaxin concentrations slightly improved the detection rate of a previously derived prediction model for LO-PE from 42.5% to 45.1% at a fixed 10% false-positive rate. Relaxin shows little improvement in the performance of first trimester prediction models, which does not support its clinical implementation as a biomarker. Although this study was only correlational, the results point to a possible pathophysiologic role for low relaxin levels in pregnancies that later develop LO-PE.

Effect of relaxin on cryopreserved beef bull semen characteristics

This study aimed to improve the quality of cryopreserved beef bull (Piedmontese) semen by incorporation of relaxin in diluted semen before cryopreservation procedures. Semen samples were collected from 4 proven fertile bulls, using artificial vagina, once per week for 8 consecutive weeks and pooled together then diluted with Bullxcell® extender, and supplemented with different concentrations of relaxin (0 (control), 25, 50 and 100 ng/ml) before cooling, equilibration and freezing procedures. Frozen semen was thawed and assessed for motility by Computer-Assisted Sperm Analysis and vitality parameters such as acrosome, plasma membrane and DNA integrities, apoptosis, mitochondrial membrane potential, mucus penetration and SOD activity. The developmental potential of bovine embryos produced in vitro by using relaxin-treated was also investigated. In the present study, 50 and 100 ng/ml relaxin incorporation in extended bull semen before cryopreservation induced a reduction of sperm motility immediately after thawing (0h), whereas, during long incubation periods (1–2 h), relaxin showed a significant positive effect on sperm quality by improving the sperm motility and velocity parameters. Interestingly, sperm vitality was improved by 25 and 100 ng/ml relaxin and the blastocyst developmental rate was significantly increased in the 25 ng/ml relaxin group compared with controls (52/118, 44.0% vs. 32/116, 27.6%, respectively). These findings suggest a potential use of relaxin at the doses tested in the present study as an additive in the cryopreservation media of bull semen to improve sperm quality.

Characterizing relaxin receptor expression and exploring relaxin\u2019s effect on tissue remodeling/fibrosis in the human bladder

BackgroundRelaxin is an endogenous protein that has been shown to have antifibrotic properties in various organ systems. There has been no characterization of relaxin’s role in the human bladder. Our objective was to characterize relaxin receptor expression in the human bladder and assess relaxin’s effect on tissue remodeling/fibrosis pathways in bladder smooth muscle cells.MethodsRelaxin family peptide receptor 1 (RXFP1) and RXFP2 expression was assessed using quantitative reverse transcriptase-PCR (qRT-PCR) and immunohistochemistry (IHC) on primary bladder tissue. Primary human smooth muscle bladder cells were cultured and stimulated with various concentrations of relaxin. Western blot, qRTPCR, ELISA, and zymogram assays were used to analyze fibrosis/tissue remodeling pathway proteins.ResultsThere was universal mRNA transcript detection and protein expression of relaxin receptors in primary bladder specimens. Immunohistochemistry demonstrated RXFP1 and RXFP2 localizing to both urothelial and smooth muscle cell layers of the bladder. 24 h of in vitro relaxin stimulation did not affect mRNA expression of selected proteins in human bladder smooth muscle cells. However, 48 h of in vitro relaxin stimulation resulted in upregulation of active (p = 0.004) and latent (p = 0.027) MMP-2 in cell lysate, and upregulation of active MMP-2 in supernatant (p = 0.04). There was a dose dependent relationship with increasing expression of MMP-2 with increasing relaxin concentration. Relaxin stimulation resulted in decreased levels of active and total TGF-β1 in supernatant and extracellular matrix (p < 0.005 with 100 ng/mL relaxin stimulation).ConclusionsIn the human bladder, relaxin receptors are expressed at the dome and trigone and localize to the urothelium and smooth muscle cell layers. Stimulation of human bladder SMCs with relaxin in vitro affects expression of MMP-2 and TGF-β1.

Effect of relaxin on semen quality variables of cryopreserved stallion semen

The aim of the study was to ascertain effects of different concentrations of relaxin added to extender medium during the pre-freezing incubation periods on quality variables of stallion frozen-thawed spermatozoa. Semen samples collected from three stallions were filtered, diluted with skim milk, and centrifuged at 600g for 10 min. Sperm pellets were suspended in BotuCrio freezing medium to a final concentration of 50 × 106 sperm/mL. The diluted semen was divided into five experimental groups supplemented with 0 (control), 12.5, 25, 50, or 100 ng/mL of relaxin. The semen samples were transferred into 0.5 mL straws, equilibrated at 5 °C for 30 min, and placed in liquid nitrogen (LN2) vapour for 15 min before being plunged into LN2. After thawing, sperm samples were evaluated for motility and velocity variables, mitochondrial membrane potential, apoptosis, and plasma membrane and DNA integrities. For sperm motility variables, there were dose- and time-dependent effects, with the largest values recorded when 12.5 and 25 ng/mL relaxin were used for 0–120 min of incubation. Furthermore, at all of the concentrations at which there were evaluations, relaxin additions to semen diluent led to a marked improvement in sperm mitochondrial membrane potential and a lesser percentage of apoptotic cells compared to the control group. Plasma membranes and DNA integrities were not affected by relaxin supplementations to the diluent. In conclusion, supplementation of relaxin in extender before semen cryopreservation, especially at 12.5 and 25 ng/mL, had a positive effect on the sperm quality variables.

EVALUATION OF SERUM RELAXIN CONCENTRATIONS AND KNEE VALGUS AFTER ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION

Background:Athletes who sustain an anterior cruciate ligament (ACL) injury are more likely to develop adverse health outcomes, such as knee osteoarthritis, knee pain, and obesity. It is assumed that the long-term consequences of ACL reconstruction are caused by the reconstruction itself. Studies have observed that relaxin, a peptide hormone similar in structure to insulin, interferes with the structural integrity of the ACL and elicits long term effects on bone, joint, muscle, and tendon health. Given the known effects of relaxin, it is reasonable to wonder if relaxin contributes to the development of these long-term health outcomes, independently of the ACL injury.Hypothesis/Purpose:The purpose of this study was to evaluate knee valgus and serum relaxin concentrations (SRC) in athletes who have and have not sustained an ACL injury. It was hypothesized that athletes who previously tore their ACL would have higher SRC and more knee valgus than those who were injury free.Methods:Twenty-two female athletes participated. Participants were assigned to one of two groups: ACL injury (6.0 ± 3.3 years after surgery, N = 4) and injury free (N = 18). Kinematic data were collected at 100 Hz using The MotionMonitor. Participants performed a single leg squat (SLS), single leg crossover dropdown (SCD), and drop vertical jump (DVJ) at two different time points in their menstrual period: pre-ovulatory phase and mid-luteal phase. Blood samples were collected when SRC are measurable (mid-luteal phase), and SRC were determined using a Quantikine Human Relaxin-2 Immunoassay.Results:Independent samples t-tests revealed significant differences between those who tore their ACL and those who were injury free in SRC and knee valgus during the SLS in the mid luteal phase, DVJ in both phases, and SCD in both phases. Specifically, the participants who tore their ACL had significantly higher SRC and more knee valgus than those who did not tear their ACL.Conclusion:These findings suggest that a previous ACL injury could place one at an increased risk of re-tear and other adverse effects on their joints, muscles, and tendons. Thus, further investigating hormonal risk factors during long term monitoring of recovery is needed.

The Relationship between Serum Relaxin Concentrations and Knee Valgus.

Female athletes are at an elevated risk for tearing their anterior cruciate ligament, compared to their male counterparts. Though injury screening clinical tests and neuromuscular training programs have been widely implemented, injury rates remain high among female athletes. The purpose of this study was to examine the relationship between serum relaxin concentrations and knee valgus during three clinical tests (single leg squat, drop vertical jump, and single leg crossover dropdown). Twenty-two female athletes volunteered. Participants were scheduled for collection during the mid-luteal phase, when serum relaxin concentrations are known to be measurable. Blood samples were collected, and serum relaxin concentrations were quantified. Kinematic data were collected while participants performed the three clinical tests. Regression analyses revealed statistically significant relationships between serum relaxin concentrations and knee valgus throughout all tests. These findings suggest that serum relaxin concentrations and knee valgus are not independent of each other and more holistic approaches may be necessary to truly map out the risk for injury and ultimately reduce the rate of anterior cruciate ligament injuries. Thus, concluding that knee valgus, a highly utilized modifiable biomechanical risk factor, and relaxin, a hormone that has been associated with anterior cruciate ligament injury in female athletes, are related to each other.

Preliminary Evaluation of Dynamic Knee Valgus and Serum Relaxin Concentrations After ACL Reconstruction.

Background:Athletes who have sustained a tear of the anterior cruciate ligament (ACL) are at a greater risk of re-tear and of developing other adverse outcomes, such as knee osteoarthritis, compared with uninjured athletes. Relaxin, a peptide hormone similar in structure to insulin, has been shown to interfere with the structural integrity of the ACL in female individuals. The purpose of the present study was to evaluate dynamic knee valgus and the serum relaxin concentration (SRC) in athletes who had previously sustained a torn ACL and in those who had not.Methods:The study included 22 female athletes, divided into 2 groups: those who had previously sustained a torn ACL (4 participants; torn ACL in the dominant leg in all cases) and those who had not (18 participants). Kinematic data were collected at 100 Hz. To assess dynamic knee valgus, participants performed a single-leg squat, a single-leg crossover dropdown, and a drop vertical jump at 2 time points in the menstrual cycle of the patient, pre-ovulatory and mid-luteal. SRC was determined with use of the Human Relaxin-2 Immunoassay using a blood sample obtained during the mid-luteal phase of the menstrual cycle.Results:Independent samples t tests were utilized to compare the differences in dynamic knee valgus and SRC between groups. For the single-leg squat, participants with a prior torn ACL were found to have significantly higher dynamic knee valgus at the mid-luteal phase but not at the pre-ovulatory phase. For the drop vertical jump and single-leg crossover dropdown, participants with a prior torn ACL were found to have significantly higher dynamic knee valgus at both the pre-ovulatory and mid-luteal phases. SRC was also significantly higher among participants with a prior torn ACL.Conclusions:Participants who had previously sustained a torn ACL had higher SRC and more dynamic knee valgus compared with those who had not. Further investigation of the effects of hormones as a risk factor for reinjury in participants with a prior ACL tear may be worthwhile. In addition, it may be worth monitoring hormonal and biomechanical properties in athletes during the long-term recovery from ACL reconstruction.Level of Evidence:Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Relaxin inhibits patellar tendon healing in rats: a histological and biochemical evaluation

BackgroundFemale patients are more likely to have tendon injuries than males, especially those who has a higher concentration of relaxin. Previous studies have demonstrated that relaxin attenuates extracellular matrix (ECM) formation. However, the mechanism of relaxin on tendon repair remains unclear. We hypothesize that relaxin inhibits tendon healing by disrupting collagen synthesis.MethodsA patellar tendon window defect model was established using Sprague-Dawley rats. The center of the patellar tendon was removed from the patella distal apex and inserted to the tibia tuberosity in width of 1 mm. Then, the rats were injected with saline (0.2 μg/kg/day) or relaxin (0.2 μg/kg/day) for two and four weeks, which was followed by biomechanical analysis and histological and histochemical examination.ResultsMechanical results indicated that relaxin induces a significant decrease in tear resistance, stiffness, and Young’s modulus compared to those rats without relaxin treatment. In addition, it was shown that relaxin activates relaxin family peptide receptor 1(RXFP1), disturbs the balance between matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteases (TIMPs), and reduces the deposition of collagen in injury areas.ConclusionsRelaxin impairs tendon healing in rats. Also, relaxin might lead to tendon injury more commonly for females than males.

Optimal Paradigms for Measuring Peak Serum Relaxin in Eumenorrheic, Active Females

Sex disparity in anterior cruciate ligament injury is multifactorial. Sex hormones, such as relaxin, may play a role in the increased risk of injury in female athletes. In order to fully investigate this relationship, optimal strategies for capturing serum relaxin concentration across the menstrual cycle must be determined. The aim of this study was to describe the variability in the timing and magnitude of relaxin concentration changes across the menstrual cycle.

Priming with oxytocin and relaxin improves cardiac differentiation of adipose tissue-derived stem cells.

Previous studies have identified the heart as a source and a target tissue for oxytocin and relaxin hormones. These hormones play important roles in the regulation of cardiovascular function and repair of ischemic heart injury. In the current study, we examined the impact of oxytocin and relaxin on the development of cardiomyocytes from mesenchymal stem cells. For this purpose, mouse adipose tissue-derived stem cells (ADSCs) were treated with different concentrations of oxytocin or relaxin for 4 days. Three weeks after initiation of cardiac induction, differentiated ADSCs expressed cardiac-specific genes, Gata4, Mef2c, Nkx2.5, Tbx5, α- and β-Mhc, Mlc2v, Mlc2a and Anp, and cardiac proteins including connexin 43, desmin and α-actinin. 10 -7 M oxytocin and 50 ng/mL relaxin induced the maximum upregulation in the expression of cardiac markers. A combination of oxytocin and relaxin induced cardiomyocyte differentiation more potently than the individual factors. In our experiment, oxytocin-relaxin combination increased the population of cardiac troponin I-expressing cells to 6.84% as compared with 2.36% for the untreated ADSCs, 3.7% for oxytocin treatment and 3.41% for relaxin treatment groups. In summary, the results of this study indicated that oxytocin and relaxin hormones individually and in combination can improve cardiac differentiation of ADSCs, and treatment of the ADSCs and possibly other mesenchymal stem cells with these hormones may enhance their cardiogenic differentiation and survival after transplantation into the ischemic heart tissue.