Placental contribution to the endocrinology of gestation and parturition

In addition to many other functions, the placenta is a source of a vast number of autocrine, paracrine and endocrine factors. However, the spectrum of placental regulatory factors, their concentrations, gestational profiles and roles may differ considerably even between phylogenetically closely related species. Depending on the species, placental regulatory factors of a broad range of molecule classes have been found including (glyco- )proteins, peptides, steroids and prostaglandins. Local placental regulatory factors are especially important for the dialogue between the fetal and the maternal compartment immediately at the feto-maternal borderline and for the control of growth, differentiation and functions of the placenta itself. Moreover, placental hormones in a proper sense may also have effects in more remote targets within the maternal compartment, serving functions such as pregnancy-specific adaptations of maternal circulation, provision of hemotrophe to the fetus or the development and function of the mammary gland. Functions of placental hormones in the fetus proper are less clear but may be especially important before the establishment of a functional fetal endocrine system and near term within the highly species-specific networks of signals preparing and initiating parturition. This review takes a comparative view on the situation in different domestic animals focusing on ruminants and on placental hormones occurring at significant concentrations in the maternal circulation.

Placental contribution to the endocrinology of gestation and parturition

In addition to many other functions, the placenta is a source of a vast number of autocrine, paracrine and endocrine factors. However, the spectrum of placental regulatory factors, their concentrations, gestational profiles and roles may differ considerably even between phylogenetically closely related species. Depending on the species, placental regulatory factors of a broad range of molecule classes have been found including (glyco- )proteins, peptides, steroids and prostaglandins. Local placental regulatory factors are especially important for the dialogue between the fetal and the maternal compartment immediately at the feto-maternal borderline and for the control of growth, differentiation and functions of the placenta itself. Moreover, placental hormones in a proper sense may also have effects in more remote targets within the maternal compartment, serving functions such as pregnancy-specific adaptations of maternal circulation, provision of hemotrophe to the fetus or the development and function of the mammary gland. Functions of placental hormones in the fetus proper are less clear but may be especially important before the establishment of a functional fetal endocrine system and near term within the highly species-specific networks of signals preparing and initiating parturition. This review takes a comparative view on the situation in different domestic animals focusing on ruminants and on placental hormones occurring at significant concentrations in the maternal circulation.(AU)

Relaxin in the male reproductive system

xin (RLN) belong s to a family of hormones structurally related to insulin and presents a broad spectrum of actions. H umans have three forms of RLN , encoded by three different genes ( RLN1 , RLN2 and RLN3 ) , but nonprimate vertebrate s have only two forms of relaxin (RLN1 and RLN3) . RLN1 of these animals is encoded by Rln1 , orthologous to the h uman RLN 2 gene , and both genes , Rln1 and human RLN2 , encode the major form of relaxin found in the male reproductive system . In the reproductive tract of human male s , RLN is mainly produced by the prostate and secreted into the seminal fluid, where it seems to play a role in sperm function. R LN may also play a role in prostate cancer progression. A lack of RLN in animal models impairs male fertili ty , and RLN knockout mice display decreased sperm maturation . T he precise role of RLN in the male reproductive system , however , is still far from clear. RLN actio n is due to its interaction with the G - protein coupled receptor RXFP1. Studies from our labora tory have shown that RLN and RXFP1 are e x pressed in rat Sertoli cells, and e x ogenous RLN stimulates Sertoli cell proliferation. RLN receptors can also be detected in rat germ cells at different stages of development, suggesting that RLN may play a direct r ole in spermatogenesis. The distribution of RLN/RXFP1 , however , appears to be species - dependent, because i n the boar testis RLN production seems restricted to the Leydig cells, whereas RXFP1 is found in Leydig, Sertoli and germ cells. The co - expression of RLN and RXFP1 in several regions of the male reproductive system suggest s that the peptide may act in an autocrine/paracrine fashion.

Relaxin in the male reproductive system

xin (RLN) belong s to a family of hormones structurally related to insulin and presents a broad spectrum of actions. H umans have three forms of RLN , encoded by three different genes ( RLN1 , RLN2 and RLN3 ) , but nonprimate vertebrate s have only two forms of relaxin (RLN1 and RLN3) . RLN1 of these animals is encoded by Rln1 , orthologous to the h uman RLN 2 gene , and both genes , Rln1 and human RLN2 , encode the major form of relaxin found in the male reproductive system . In the reproductive tract of human male s , RLN is mainly produced by the prostate and secreted into the seminal fluid, where it seems to play a role in sperm function. R LN may also play a role in prostate cancer progression. A lack of RLN in animal models impairs male fertili ty , and RLN knockout mice display decreased sperm maturation . T he precise role of RLN in the male reproductive system , however , is still far from clear. RLN actio n is due to its interaction with the G - protein coupled receptor RXFP1. Studies from our labora tory have shown that RLN and RXFP1 are e x pressed in rat Sertoli cells, and e x ogenous RLN stimulates Sertoli cell proliferation. RLN receptors can also be detected in rat germ cells at different stages of development, suggesting that RLN may play a direct r ole in spermatogenesis. The distribution of RLN/RXFP1 , however , appears to be species - dependent, because i n the boar testis RLN production seems restricted to the Leydig cells, whereas RXFP1 is found in Leydig, Sertoli and germ cells. The co - expression of RLN and RXFP1 in several regions of the male reproductive system suggest s that the peptide may act in an autocrine/paracrine fashion.(AU)

Inércia uterina e maceração fetal após aplicação incorreta do acetato de medroxiprogesterona em gata: relato de caso / Uterine inertia and fetal maceration after misapplication of medroxyprogesterone in cat: case report / Inercia uterina y la maceración del feto después de la aplicación errónea de medroxiprogesterona in la gata: reporte de un caso

O acetato de medroxiprogesterona (MA) é administrado em cadelas e gatas para supressão do estro. Porém, seu uso na gestação pode levar à distocia, salientando a importância em discutir os seus prováveis mecanismos de ação. Avaliou-se o caso de uma gata com secreção vaginal purulenta e não desencadeamento do parto, após aplicação do MA na gestação. Foi diagnosticada mace ração fetal e realizada ovariosalpingohisterectomia (OSH), com resolução da afecção. Os mecanismos pelos quais os progestágenos promovem a quiescência uterina ainda não são completamente conhecidos. Em outras espécies sugere-se ação nos níveis intracelulares de cálcio e de relaxina; nos receptores para ocitocina e na síntese de prostaglandina. No caso relatado, acredita-se que o MA inibiu a contração uterina e a abertura cervical desencadeou a maceração fetal.(AU)

The medroxyprogesterone acetate (MA) is administered to dogs and cats for suppression of oestrus. However, its use during pregnancy can lead to dystocia, emphasizing the importance of discussing their possible mechanisms of action. It was evaluated the case of a cat with purulent vaginal discharge and not onset the birth, after application of MA during pregnancy. Was diagnosed fetal maceration and performed ovariosalpingohisterectomy (OSH), with resolution of the disease. The mechanisms by which the incorrect administration of MA leads to not trigger parturition in cats are not fully understood. In other species suggest action on the intracellular calcium levels and relaxin; the receptors for oxytocin and prostaglandin synthesis. In the reported case, it is believed that MA inhibited uterine contraction and cervical opening triggered fetal maceration.(AU)

El acetato de medroxiprogesterona (MA) se administra a los perros y gatos para la supresión del estro. Sin embargo, su uso durante el embarazo puede causar distocia, haciendo hincapié en la importancia de discutir sus posibles mecanismos de acción. Evaluado el caso de un gato con la secreción vaginal purulenta y no desencadenar el nacimiento, después de la aplicación del MA en el embarazo. Fue diagnosticado maceración fetal y ovariosalpingohisterectomy (OSH) celebrada el trabajo, con la resolución de la enfermedad. Los mecanismos por los que la progesterona promueve reposo uterino no están todavía completamente conocidos. En otras especies sugieren acción sobre los niveles de calcio intracelular y relaxina; los receptores de la oxitocina y la síntesis de prostaglandinas. En nuestro caso, se cree que MA inhibió la contracción uterina y la abertura cervical desencadena la maceración fetal.(AU)

Inércia uterina e maceração fetal após aplicação incorreta do acetato de medroxiprogesterona em gata: relato de caso / Uterine inertia and fetal maceration after misapplication of medroxyprogesterone in cat: case report / Inercia uterina y la maceración del feto después de la aplicación errónea de medroxiprogesterona in la gata: reporte de un caso

O acetato de medroxiprogesterona (MA) é administrado em cadelas e gatas para supressão do estro. Porém, seu uso na gestação pode levar à distocia, salientando a importância em discutir os seus prováveis mecanismos de ação. Avaliou-se o caso de uma gata com secreção vaginal purulenta e não desencadeamento do parto, após aplicação do MA na gestação. Foi diagnosticada mace ração fetal e realizada ovariosalpingohisterectomia (OSH), com resolução da afecção. Os mecanismos pelos quais os progestágenos promovem a quiescência uterina ainda não são completamente conhecidos. Em outras espécies sugere-se ação nos níveis intracelulares de cálcio e de relaxina; nos receptores para ocitocina e na síntese de prostaglandina. No caso relatado, acredita-se que o MA inibiu a contração uterina e a abertura cervical desencadeou a maceração fetal.

The medroxyprogesterone acetate (MA) is administered to dogs and cats for suppression of oestrus. However, its use during pregnancy can lead to dystocia, emphasizing the importance of discussing their possible mechanisms of action. It was evaluated the case of a cat with purulent vaginal discharge and not onset the birth, after application of MA during pregnancy. Was diagnosed fetal maceration and performed ovariosalpingohisterectomy (OSH), with resolution of the disease. The mechanisms by which the incorrect administration of MA leads to not trigger parturition in cats are not fully understood. In other species suggest action on the intracellular calcium levels and relaxin; the receptors for oxytocin and prostaglandin synthesis. In the reported case, it is believed that MA inhibited uterine contraction and cervical opening triggered fetal maceration.

El acetato de medroxiprogesterona (MA) se administra a los perros y gatos para la supresión del estro. Sin embargo, su uso durante el embarazo puede causar distocia, haciendo hincapié en la importancia de discutir sus posibles mecanismos de acción. Evaluado el caso de un gato con la secreción vaginal purulenta y no desencadenar el nacimiento, después de la aplicación del MA en el embarazo. Fue diagnosticado maceración fetal y ovariosalpingohisterectomy (OSH) celebrada el trabajo, con la resolución de la enfermedad. Los mecanismos por los que la progesterona promueve reposo uterino no están todavía completamente conocidos. En otras especies sugieren acción sobre los niveles de calcio intracelular y relaxina; los receptores de la oxitocina y la síntesis de prostaglandinas. En nuestro caso, se cree que MA inhibió la contracción uterina y la abertura cervical desencadena la maceración fetal.