Influence Of Relaxin Research Articles

The levels of relaxin and amino acids play a critical role in women with variable degree of preparedness for labour

Underlying biochemical factors that contribute towards the preparedness for labour and ripening of the cervix remain largely unknown. We aimed to characterize metabolic and hormonal determinants that constitute the preparedness for labour in women.
 The aim of the research was to study the content of relaxin and amino acids involved in its formation in primiparous pregnant women with various degrees of birth preparedness.
 Materials and methods: Prospective study has been conducted on 115 primiparous women at 38-40 weeks of gestation. Biochemical methods were used to analyse relaxin and amino acid levels in pregnant women with varying degree of birth preparedness. Results: the obtained data from the study indicate importance role of relaxin in the underlying pathogenesis in women with variable degree of preparedness for labour. The results allow to use the levels of relaxin serum as a predictor of the state of the birth canal. Furthermore, the amino acids are known to participate in various critical metabolic processes and play an important role is orchestrating many essential pathways in the body. We present the analysis of amino acids involved in the formation of relaxin in the serum of pregnant women. Our analysis has shown that amino acid imbalance leads to disruption of energy metabolism and blood flow rate, resulting in metabolic, structural and functional changes in the cervix at the onset of labour. Conclusion: considering the mechanisms of the possible influence of relaxin and amino acids on the cervical ripening, we concluded that correcting amino acid imbalance and normalising relaxin levels should be included in preinduction of labour therapeutic regimen. This would be an important step in improving the perinatal outcomes

The influence of relaxin on motility of human sperm in vitro

Sperm of healthy men were incubated in an IVF medium with relaxin at concentrations of 3, 30, 300 and 3000 ng ml-1. Immediately after addition of relaxin and 60 and 120 min later motility, progressive motility, mean path velocity, mean progressive velocity, mean linearity and mean lateral head displacement were measured with the Hamilton-Thorn motility analyser. Neither immediately after relaxin addition, nor after 60 or 120 min, was an improvement of sperm motility observed at any concentration.

Active Immunization with Relaxin Does Not Influence Objectively Determined Sperm Motility Characteristics in Rabbits: Aktive Immunisierung mit Relaxin beeinflußt objektiv nicht die Speirnatozoen-Motilitäts-Charakteristika bei Kaninchen

Two groups of 5 rabbits were actively immunized with porcine relaxin or sham immunized. Serial analysis of sperm motion characteristics using the computer assisted Hamilton-Thorn Motility Analyzer over a period of 22 weeks did not reveal any significant antibody titers in serum and seminal plasma. In consideration of the present findings and after critical review of the literature it is concluded that an influence of relaxin on sperm motility is unlikely.

The antifibrotic effects of relaxin in human renal fibroblasts are mediated in part by inhibition of the Smad2 pathway

The peptide hormone relaxin has been demonstrated to exert antifibrotic effects in renal and extrarenal tissues. The aims of this study were to identify potential anti-fibrotic effects of relaxin on human renal fibroblasts in vitro and to analyze their mechanisms. All experiments were performed in established renal fibroblast cell lines and in primary cortical fibroblasts. Effects of relaxin were analyzed on cell proliferation, apoptosis, activation of renal fibroblasts, synthesis and secretion of collagen type I and fibronectin, as well as on the secretion of matrix metalloproteinases (MMPs). Effects on transforming growth factor-beta1 (TGF-beta1) receptor binding were analyzed by flow cytometry and on TGF-beta1 signal transduction by immunoblot analyses for Smad4 and 7, translocation from cytosol to nucleus for Smad2 and 3 as well as for phosphorylated and unphosphorylated forms of p38, c-Jun NH2 terminal kinase (JNK) and extracellular-regulated protein kinase (ERK). Finally, specific siRNAs for Smad2 and 3 were applied to assess the signal transduction pathway. After stimulation with relaxin, tyrosine phosphorylation of a 220 kD protein was demonstrated, indicating interaction with the receptor. Relaxin had only modest inhibitory effects on cell proliferation, and no effects on apoptosis. Conversely, relaxin exerted robust effects on TGF-beta1-induced fibroblast to myofibroblast transformation as well as on matrix synthesis and secretion even at the smallest dose tested. The secretion of MMP-2 and MMP-9 was induced noticeably by all investigated relaxin concentrations. TGF-beta1 receptor binding was not influenced by relaxin; however, it prevented Smad2 phosphorylation, translocation to nucleus, and complex formation between Smad2 and 3 indicating a possible interaction with TGF-beta1 signaling. These findings were corroborated by studies using siRNAs to Smad2 and 3 where siRNA to Smad2 but not to Smad3 inhibited the TGF-beta1 induction of fibronectin synthesis. There was no influence of relaxin on intracellular Smad3, Smad4, and Smad7 translocation or phosphorylation of mitogen-activated protein (MAP) kinases. Relaxin is a potent inhibitor of TGF-beta1-induced extracellular matrix (ECM) synthesis and secretion as well as fibroblast activation. Furthermore, it induces ECM degradation by induction of MMP-2 and MMP-9. These effects are mediated, at least in part, by inhibition of TGF-beta1 signaling.

Relaxin Favors the Morphofunctional Integration between Skeletal Myoblasts and Adult Cardiomyocytes in Coculture

We have investigated the interaction between mouse skeletal myoblasts and rat cardiomyocytes in coculture and the influence of relaxin. Connexin43 expression, Lucifer yellow microinjection, Ca2+ propagation, and electrophysiological analysis have shown that myoblasts and cardiomyocytes are coupled by functional gap junctions. Cardiomyocytes and relaxin upregulated connexin43 expression and gap junctional communication in myoblasts. Relaxin also increased transjunctional current between myoblasts and between myoblasts and cardiomyocytes. In conclusion, relaxin potentiates the intercellular coupling, upregulating the transcellular exchange of regulatory molecules between myoblasts and cardiomyocytes, including Ca2+. This could favor the transdifferentiation of myoblasts toward a cardiac phenotype.

Myogenic reactivity is reduced in small renal arteries isolated from relaxin-treated rats.

Administration of the ovarian hormone relaxin to nonpregnant rats vasodilates the renal circulation comparable to pregnancy. This vasodilation is mediated by endothelin (ET), the ET(B) receptor, and nitric oxide. Furthermore, endogenous relaxin mediates the renal vasodilation and hyperfiltration that occur during gestation. The goal of this study was to investigate whether myogenic reactivity of small renal and mesenteric arteries is reduced in relaxin-treated rats comparable to the pregnant condition. Relaxin or vehicle was administered to virgin female Long-Evans rats for 5 days at 4 microg/h, thereby producing midgestational blood levels of the hormone. The myogenic responses of small renal arteries (200-300 microm in diameter) isolated from these animals were evaluated in an isobaric arteriograph system. Myogenic reactivity was significantly reduced in the small renal arteries from relaxin-treated compared with vehicle-treated rats. The reduced myogenic responses were mediated by the ET(B) receptor and nitric oxide since the selective ET(B) receptor antagonist RES-701-1 and the nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester restored myogenic reactivity to virgin levels. The influence of relaxin was not limited to the renal circulation because myogenic reactivity was also reduced in small mesenteric arteries isolated from relaxin-treated rats. Thus relaxin administration to nonpregnant rats mimics pregnancy, insofar as myogenic reactivity of small renal and mesenteric arteries is reduced in both conditions.

A note on the influence of added relaxin on the fertility of aged boar semen

Two experiments were performed to evaluate the influence of relaxin on the fertility of gilts inseminated with aged boar semen. For experiment 1, oestrus was induced in 43 Yorkshire × Landrace gilts by injection of 400 i.u. PMSG plus 200 i.u. hCG. At 24 h after oestrus detection, gilts were inseminated with fresh semen (1 to 2 day old; no. = 15), aged semen (5 to 6 days old; no. = 15) or aged semen containing 400 fig/l of relaxin added at the time of semen extension (no. = 13). Pregnancy rates 24 days after insemination were lower in gilts receiving aged semen (P < 0·05), an effect not prevented by added relaxin. There was no effect of either semen age or relaxin on numbers of embryos. In experiment 2, the ejaculates of eight boars were extended with or without the addition of 400 fig/I relaxin and motility monitored for 7 days. Fresh sperm motility decreased from 87-5 (s.e. 2·5)% at collection to 71-2 (s.e. 3·3)% after 7 days. The attenuation of sperm motility was not affected by relaxin.

Physiology of parturition

A normal course of parturition requires both softening and dilatation of the cervix. Cervical softening already begins during late gestation under the influence of relaxin and/or oestrogens and occurs more rapidly close to term when the progesterone dominance is waning and uterine prostaglandin (PG) production increases. Biochemical changes within the ground substance of the connective tissue fibres result in dilution or breakdown of cervical collagen. Contrary to the active dilatation, this passive preparation of the soft tissues of the birth canal takes place in the absence of labour-like uterine contractions. Evidence in ruminants even suggests that the typical pattern of myometrial contractures, which can be recorded during the greater part of gestation, disappears during progesterone withdrawal, resulting in a prolonged period of complete myometrial quiescence, before labour-like contractions stan to develop. This may create a period of transformation during which several structural and functional changes take place within the uterine tissues, such as increased output of PGs by the placenta and fetal membranes, water uptake and collagenolysis in the cervix, synthesis of proteins involved in gap-junctions formation, and an increase of oxytocin receptors in the uterine wall. Maternal controlling mechanisms, such as an escape from direct myometrial inhibition by relaxin and catecholamines, or abolition of central inhibition of oxytocin release by relaxin and opioids, may finally switch on the myometrium to effect cervical dilatation and expulsion of the conceptus.

Monoclonal antibodies specific for rat relaxin. II. Passive immunization with monoclonal antibodies throughout the second half of pregnancy disrupts birth in intact rats.

The purpose of this investigation was to use an approach targeted specifically on endogenous relaxin to determine the influence of relaxin on birth in the rat. To that end, a monoclonal antibody specific for rat relaxin, designated MCA1, was used to passively neutralize endogenous relaxin in intact pregnant rats. MCA1 was administered iv to intact rats daily from days 12-22 of pregnancy. Animals were observed for birth continuously from 2100 h on day 22 until 1200 h on day 24. MCA1-treated rats exhibited significantly prolonged durations of straining and litter delivery as well as reduced incidence of live pups compared with controls. Whereas approximately 20-25% of fetuses and placentae were retained in utero at 1200 h on day 24 in MCA1-treated rats, neither fetuses nor placentae were retained in control rats. Passive immunization with MCA1 throughout the second half of pregnancy had no apparent influence on normal ovarian function. The time of occurrence of the antepartum decline in serum progesterone levels (functional luteolysis) as well as the time interval between the attainment of basal progesterone levels and the onset of litter delivery in MCA1-treated and control rats that delivered on day 23 were in close agreement with previous reports. In conclusion, the prolonged durations of straining and litter delivery, reduced incidence of live pups, and increased incidence of retained fetuses and placentae after passive immunization with MCA1 establish the physiological need for endogenous relaxin to attain normal delivery of the young in the rat.

Monoclonal antibodies specific for rat relaxin. I. Production and characterization of monoclonal antibodies that neutralize rat relaxin's bioactivity in vivo.

The physiological role of relaxin during pregnancy and at parturition in the rat is not absolutely established. There are limitations to the experimental approach used in the few studies that examined the influence of relaxin in the pregnant rat. These studies were unphysiological, since they involved administration of porcine relaxin as well as progesterone and estrogen to ovariectomized pregnant rats. A more physiological approach is to use antibodies to neutralize the biological actions of endogenous relaxin in the intact pregnant rat. The purpose of the present study was to produce and characterize monoclonal antibodies suitable for this approach. Six stable and rapidly growing hybridoma clones which produced monoclonal antibodies specific for rat relaxin (MCA-rR) were obtained after the fusion of NSO mouse myeloma cells with lymphocytes from the spleen of a BALB/c mouse immunized with rat relaxin. Five MCA-rR (MCA1-5; all immunoglobulin G1 kappa) inhibited the ability of exogenously administered rat relaxin to increase the interpubic ligament length in estrogen-primed mice. Of the five MCA-rR that neutralized rat relaxin's bioactivity in vivo, MCA1 exhibited the highest relative affinity for rat relaxin. MCA1 was also highly specific for rat relaxin. MCA1 demonstrated no cross-reactivity with rat insulin, rat insulin-like growth factor I and II, or porcine relaxin-proteins that are structurally related to rat relaxin. In view of its high affinity and high specificity for rat relaxin as well as its ability to neutralize rat relaxin's bioactivity in vivo, MCA1 was selected for use in subsequent studies aimed at the neutralization of endogenous relaxin in intact pregnant rats.

The influence of relaxin, with steroid pretreatment, on cervical dilatation in ovariectomized ewes

The influence of relaxin, with steroid pretreatment, on cervical dilatation in ovariectomized ewes

The physiological role of relaxin in the pregnant rat. III. The influence of relaxin on cervical extensibility.

Cervices from day 18 (D18) intact pregnant rats show significantly greater extensibility and ability to accommodate to extension than cervices from D9 pregnant rats. On D22, cervices from intact pregnant rats show even greater extensibility and accommodation to stretch. Cervices from ovariectomized pregnant rats treated with estrogen (E) and progesterone (P; group OPE) show markedly reduced extensibility and ability to accommodate to stretch compared with intact pregnant cervical tissue (group C) on both D18 and D22. Extensibility of group OPE cervices resembles that of cervices from D9 intact pregnant rats. Cervices from ovariectomized pregnant rats treated with E, porcine relaxin (R), and P (group OPER) or porcine R and P (group OPR) exhibit similar extensibility and ability to accommodate to stretch as cervices from intact pregnant rats on both D18 and D22. The importance of R for cervical softening during pregnancy and its interaction with E near term and during parturition are discussed.

Uterine size and glycogen content in cycling and pregnant rats: influence of relaxin.

Uterine weight and glycogen content were measured at stages of the estrous cycle and in the gravid and nongravid horns of unilaterally pregnant rats. The response of these parameters to administration of a purified preparation of porcine relaxin (relaxin B) was assessed during the estrus-diestrus interval and at Day 15 of gestation. Both uterine weight and glycogen content were greatest at proestrus and estrus and lowest at diestrus-1; when 0.1 mg of relaxin was administered beginning at estrus and injected over a 24 h period, the decline in uterine weight and glycogen was retarded. During gestation uterine weight declined prior to implantation and increased rapidly thereafter to a peak at Day 22 beyond which uterine size decreased through parturition. Uterine glycogen content followed similar increases except that the peak occurred on Day 23 and was sharply defined in advance of parturition at which time a rapid decline was observed. The increases in uterine weight and glycogen were significantly greater in the gravid horn than in the nongravid horn, and on the day of parturition both horns exhibited the highest glycogen concentration in the myometrium alone. Injection of relaxin at Day 15 of gestation increased uterine weight and glycogen content significantly in the myometrium of the nongravid horn without affecting the highly variable parameters in the gravid horn. Since uterine glycogen and tissue growth profiles parallel recently reported RIA relaxin concentrations in rats rather than changes in steroid hormone levels, these data suggest that relaxin may play a significant role in the uterine accommodation and glycogen storage which occur during late gestation.

The influence of relaxin on mammary gland development in guinea-pigs and rabbits.

An attempt has been made to determine the influence of relaxin on the early development of the mammary glands in rabbits and guinea-pigs. Spayed females of both species were treated with α-oestradiol and an extract containing relaxin, after a preliminary course of the steroid alone. In all cases the total treatment was limited to 20 days. Animals given only oestradiol served as controls. While the data presented are insufficient to substantiate without doubt an influence of relaxin per se on the development of the mammary tissue, they indicate that it enhances mammary development. In the guinea-pig this was in the form of a general growth stimulus; in the rabbit it appeared to consist of a transfer of emphasis from primary duct development to that of the entire duct system of the gland. The conclusion drawn from this study is that relaxin acts as a potentiator of oestrogen, working with the latter to produce greater and more normal development of the mammary glands.

Influence of Relaxin on Mammary Development in Sexually Immature Female Rats.

The only physiological action so far established for relaxin1 is the relaxation of the pelvic ligaments in the guinea pig. This preliminary paper reports observations on the effects of relaxin on mammary gland development in immature rats.Various combinations of estradiol, progesterone and relaxin were given to ovariectomized immature rats to determine the effects on the growth of mammary glands. The estradiol and progesterone were dissolved in sesame oil and injected once a day. The relaxin was dissolved in distilled water and injected in two equal doses, one in the morning and one at night. All injections were made subcutaneously. The animals used were immature female rats which had been ovariectomized at 30 days after birth. After 6 days of postoperative rest they were injected daily with 0.83 μg estradiol for 13 days. This was the standard pre-treatment given all animals before each of the following experiments. A minimum of 4 animals was used in each group cited below and the reactions within each gr...