Relaxin is a hormone produced by the ovaries, placenta, and other tissues in horses. It is involved in various reproductive processes, including the relaxation of the pelvic ligaments and cervix in preparation for parturition. Relaxin's role extends to influencing uterine growth and development during pregnancy. In equine studies, relaxin levels can be measured to assess reproductive status and health. This page compiles peer-reviewed research studies and scholarly articles that explore the production, function, and potential applications of relaxin in equine reproductive health and management.
Profaska M, Zarzycka M, Dubniewicz K, Witkowski M, Wieczorek J, Gil D, Wafula S, Lanh DK, Kotula-Balak M.Mare endometrosis remains a poorly understood pathological process. Objective: Mare endometrial tissue with endometrosis was used to determine the effects of relaxin (RLX). Healthy tissues that were left untreated (H), or treated with vehicle (Hveh), and tissues with endometrosis that were left untreated (E), treated with vehicle (Eveh), and treated with RLX (10, 25, 50 nM; ER) were used for an ex vivo system for 72 h. Methods: Tissue histological examination, and immunoenzymatic measurement of the concentrations of transforming growth factor β (TGF-β), interleukins (IL-6 and IL-8), and pr...
Kędzierski W, Kowalik S, Maśko M, Janczarek I, Bełkot Z.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 ma...
Maśko M, Zdrojkowski Ł, Wierzbicka M, Domino M.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 l...
Klein C."Maternal recognition of pregnancy" (MRP) is commonly used to describe the ongoing embryo-maternal communication during early pregnancy that culminates in prevention of luteolysis and ensures ongoing progestin support. The conceptus-derived pregnancy recognition signal has not yet been identified in the mare. Although equine conceptuses produce substantial amounts of estrogens, there is a lack of evidence that estrogens are the pregnancy recognition signal in mares. Conceptus mobility is integral to MRP and is driven by conceptus-derived prostaglandin production. Cessation of conceptus mobilit...
Ryan PL, Klonisch T, Yamashiro S, Renaud RL, Wasnidge C, Porter DG.Immunoreactive, chromatographic and molecular techniques were used to study the expression of relaxin in mare ovaries at different stages of the oestrous cycle. Relaxin in follicular fluid ranged from 1.6 to 2.5, from 1.4 to 5.2, from 1.2 to 6.7 and from 1.0 to 3.5 ng ml-1 in small ( 2 3 4 cm) follicles, respectively, and total content of fluid relaxin per follicle increased (P < 0.05) with follicular size. When subjected to reverse phase HPLC analysis, follicular fluid yielded absorbance profiles corresponding closely to those of purified relaxin, and immunoreactive peaks in follicular f...
Stewart DR, Stabenfeldt GH, Hughes JP.Plasma relaxin concentrations were measured hourly by radio immunoassay in 4 pregnant mares from 11 days before until 4 days after natural foaling. Pre-partum levels ranged from 4 to 7 ng/ml without any surge until the second stage of labour when they increased rapidly to about 11 ng/ml. In 3 of these mares, relaxin activity declined immediately after the expulsion of the placenta and was below detectable levels within 36 h. In the other mare relaxin activity did not fall until after the mechanical removal of the placenta 7 h after foaling. Eight mares were induced to foal by the administratio...
Klein C."Maternal recognition of pregnancy" (MRP) is commonly used to describe the ongoing embryo-maternal communication during early pregnancy that culminates in prevention of luteolysis and ensures ongoing progestin support. The conceptus-derived pregnancy recognition signal has not yet been identified in the mare. Although equine conceptuses produce substantial amounts of estrogens, there is a lack of evidence that estrogens are the pregnancy recognition signal in mares. Conceptus mobility is integral to MRP and is driven by conceptus-derived prostaglandin production. Cessation of conceptus mobilit...
Maśko M, Zdrojkowski Ł, Wierzbicka M, Domino M.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 l...
Ryan PL, Klonisch T, Yamashiro S, Renaud RL, Wasnidge C, Porter DG.Immunoreactive, chromatographic and molecular techniques were used to study the expression of relaxin in mare ovaries at different stages of the oestrous cycle. Relaxin in follicular fluid ranged from 1.6 to 2.5, from 1.4 to 5.2, from 1.2 to 6.7 and from 1.0 to 3.5 ng ml-1 in small ( 2 3 4 cm) follicles, respectively, and total content of fluid relaxin per follicle increased (P < 0.05) with follicular size. When subjected to reverse phase HPLC analysis, follicular fluid yielded absorbance profiles corresponding closely to those of purified relaxin, and immunoreactive peaks in follicular f...
Stewart DR, Stabenfeldt GH, Hughes JP.Plasma relaxin concentrations were measured hourly by radio immunoassay in 4 pregnant mares from 11 days before until 4 days after natural foaling. Pre-partum levels ranged from 4 to 7 ng/ml without any surge until the second stage of labour when they increased rapidly to about 11 ng/ml. In 3 of these mares, relaxin activity declined immediately after the expulsion of the placenta and was below detectable levels within 36 h. In the other mare relaxin activity did not fall until after the mechanical removal of the placenta 7 h after foaling. Eight mares were induced to foal by the administratio...
Kędzierski W, Kowalik S, Maśko M, Janczarek I, Bełkot Z.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 ma...
Profaska M, Zarzycka M, Dubniewicz K, Witkowski M, Wieczorek J, Gil D, Wafula S, Lanh DK, Kotula-Balak M.Mare endometrosis remains a poorly understood pathological process. Objective: Mare endometrial tissue with endometrosis was used to determine the effects of relaxin (RLX). Healthy tissues that were left untreated (H), or treated with vehicle (Hveh), and tissues with endometrosis that were left untreated (E), treated with vehicle (Eveh), and treated with RLX (10, 25, 50 nM; ER) were used for an ex vivo system for 72 h. Methods: Tissue histological examination, and immunoenzymatic measurement of the concentrations of transforming growth factor β (TGF-β), interleukins (IL-6 and IL-8), and pr...