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Radek Prochazka - One of the best experts on this subject based on the ideXlab platform.

  • cyclic Guanosine Monophosphate does not inhibit gonadotropin induced activation of mitogen activated protein kinase 3 1 in pig cumulus oocyte complexes
    Reproductive Biology and Endocrinology, 2015
    Co-Authors: Milan Blaha, Lucie Nemcova, Radek Prochazka
    Abstract:

    Background Recent results indicate a key role for cyclic Guanosine Monophosphate (cGMP) in the regulation of oocyte meiotic arrest in preovulatory mammalian follicles. The aim of our study was to determine whether the resumption of oocyte meiosis and expansion of cumulus cells in isolated pig cumulus-oocyte complexes (COCs) can be blocked by a high intracellular concentration of cGMP, and whether this effect is mediated by a cGMP-dependent inhibition of mitogen-activated protein kinase 3/1 (MAPK3/1).

  • Cyclic Guanosine Monophosphate does not inhibit gonadotropin-induced activation of mitogen-activated protein kinase 3/1 in pig cumulus-oocyte complexes
    Reproductive Biology and Endocrinology, 2015
    Co-Authors: Milan Blaha, Lucie Nemcova, Radek Prochazka
    Abstract:

    Background Recent results indicate a key role for cyclic Guanosine Monophosphate (cGMP) in the regulation of oocyte meiotic arrest in preovulatory mammalian follicles. The aim of our study was to determine whether the resumption of oocyte meiosis and expansion of cumulus cells in isolated pig cumulus-oocyte complexes (COCs) can be blocked by a high intracellular concentration of cGMP, and whether this effect is mediated by a cGMP-dependent inhibition of mitogen-activated protein kinase 3/1 (MAPK3/1). Methods The COCs were isolated from ovaries of slaughtered gilts and cultured in vitro in M199 supplemented with 5% fetal calf serum. The expression levels of the C-type natriuretic peptide (CNP) precursor ( NPPC ) and its receptor ( NPR2 ) mRNAs during the culture of COCs were determined by real-time RT-PCR. To control the intracellular concentration of cGMP in the COCs, the culture medium was further supplemented with CNP or various concentrations of synthetic cGMP analogues; the concentration of cGMP in COCs was then assessed by ELISA. The effect of the drugs on oocyte maturation was assessed after 24 and 44 h of culture by determining nuclear maturation. The expansion of cumulus cells was assessed by light microscopy and the expression of cumulus expansion-related genes by real-time RT-PCR. A possible effect of cGMP on FSH-induced activation of MAPK3/1 was assessed by immunoblotting the COC proteins with phospho-specific and total anti-Erk1/2 antibodies. Results The COCs expressed NPPC and NPR2 , the key components of cGMP synthesis, and produced a large amount of cGMP upon stimulation with exogenous CNP, which lead to a significant (P  0.05). Conclusions The findings of this study indicate that high cGMP concentrations inhibit the maturation of pig oocytes in vitro but the inhibitory mechanism does not involve the suppression of MAPK3/1 activation in cumulus cells.

R E Garfield - One of the best experts on this subject based on the ideXlab platform.

  • Involvement of a nitric oxide-cyclic Guanosine Monophosphate pathway in control of human uterine contractility during pregnancy.
    American journal of obstetrics and gynecology, 1995
    Co-Authors: Irina A. Buhimschi, C Yallampalli, Yuan-lin Dong, R E Garfield
    Abstract:

    Abstract OBJECTIVES: The aims of the study were to investigate whether a nitric oxide-cyclic Guanosine Monophosphate relaxation pathway is present in the human uterus and whether it differentially inhibits contractility during pregnancy and labor. STUDY DESIGN: Myometrial strips were obtained from pregnant women who were either in labor or not in labor and from nonpregnant women. Nitrites and cyclic Guanosine Monophosphate production by the tissues and contractile responses to nitric oxide modifiers were measured. RESULTS: Biochemical assays revealed that nitric oxide (nitrites) and cyclic Guanosine Monophosphate are generated by the human uterus. Cyclic Guanosine Monophosphate production by the uterus was increased by l-arginine (the substrate for nitric oxide) and diethylamine/nitric oxide (a nitric oxide donor) and decreased by nitro-l-arginine methyl ester (an inhibitor of nitric oxide synthase). Spontaneous contractility in vitro was increased by nitro-l-arginine methyl ester and decreased by diethylamine/nitric oxide, which furthermore produced a dose-dependent inhibition of contractility, and the median effective dose of inhibition in tissues from nonlaboring pregnant patients (1.5 ± 0.4 μmol/L) is substantially lower than in tissues from laboring pregnant (21.7 ± 7.4 μmol/L or nonpregnant (20.8 ± 4.4 μmol/L) women. These studies show that the nitric oxide-cyclic quanosine Monophosphate system exists in the human uterus and that it inhibits contractility. Furthermore, the relaxation responsiveness to nitric oxide is elevated during pregnancy and decreased during labor. CONCLUSION: A nitric oxide-cyclic Guanosine Monophosphate relaxation pathway is present in the human uterus and may be responsible for maintaining uterine quiescence during pregnancy. A decrease in uterine relaxation responsiveness to nitric oxide at term may play a role in the initiation of labor.

  • an l arginine nitric oxide cyclic Guanosine Monophosphate system exists in the uterus and inhibits contractility during pregnancy
    American Journal of Obstetrics and Gynecology, 1994
    Co-Authors: C Yallampalli, H Izumi, Mary Byamsmith, R E Garfield
    Abstract:

    Abstract OBJECTIVE: Nitric oxide is synthesized from L -arginine and it causes relaxation of smooth muscle by elevating cyclic Guanosine Monophosphate levels. We hypothesized that an L -arginine–nitric oxide–cGMP system is present in the uterus and modulates contractility. STUDY DESIGN: Isometric tension of the uterus was measured in vitro from pregnant rats in response to various agents that modulate nitric oxide–cyclic Guanosine Monophosphate production or action. RESULTS: Major findings are as follows: (1) The substrate and a donor of nitric oxide produced uterine relaxation; (2) inhibitors of the nitric oxide–cyclic Guanosine Monophosphate pathway blocked the relaxation responses; (3) nitric oxide synthase was localized to several uterine cell types; (4) nitric oxide was produced by the uterus during periods when L-arginine was consumed and citrulline levels increased; (5) effects of nitric oxide substrate on relaxation were mimicked by cyclic Guanosine Monophosphate; (6) nitric oxide–cyclic Guanosine Monophosphate responses were decreased during delivery; (7) L -arginine responses were increased by progesterone, and antiprogesterone treatment decreased cyclic Guanosine Monophosphate – induced relaxations. CONCLUSION: An L -arginine–nitric oxide–cyclic Guanosine Monophosphate system is present in the uterus and it may regulate relaxation during pregnancy. The inhibitory action of L -arginine and 8-bromo-cyclic Guanosine Monophosphate was considerably lower during delivery and post partum, indicating that the nitric oxide system may contribute to the maintenance of uterine quiescence during pregnancy, when progesterone levels are elevated, but not during delivery. (AM J OBSTET GYNECOL 1993;170:175-85.)

Milan Blaha - One of the best experts on this subject based on the ideXlab platform.

  • cyclic Guanosine Monophosphate does not inhibit gonadotropin induced activation of mitogen activated protein kinase 3 1 in pig cumulus oocyte complexes
    Reproductive Biology and Endocrinology, 2015
    Co-Authors: Milan Blaha, Lucie Nemcova, Radek Prochazka
    Abstract:

    Background Recent results indicate a key role for cyclic Guanosine Monophosphate (cGMP) in the regulation of oocyte meiotic arrest in preovulatory mammalian follicles. The aim of our study was to determine whether the resumption of oocyte meiosis and expansion of cumulus cells in isolated pig cumulus-oocyte complexes (COCs) can be blocked by a high intracellular concentration of cGMP, and whether this effect is mediated by a cGMP-dependent inhibition of mitogen-activated protein kinase 3/1 (MAPK3/1).

  • Cyclic Guanosine Monophosphate does not inhibit gonadotropin-induced activation of mitogen-activated protein kinase 3/1 in pig cumulus-oocyte complexes
    Reproductive Biology and Endocrinology, 2015
    Co-Authors: Milan Blaha, Lucie Nemcova, Radek Prochazka
    Abstract:

    Background Recent results indicate a key role for cyclic Guanosine Monophosphate (cGMP) in the regulation of oocyte meiotic arrest in preovulatory mammalian follicles. The aim of our study was to determine whether the resumption of oocyte meiosis and expansion of cumulus cells in isolated pig cumulus-oocyte complexes (COCs) can be blocked by a high intracellular concentration of cGMP, and whether this effect is mediated by a cGMP-dependent inhibition of mitogen-activated protein kinase 3/1 (MAPK3/1). Methods The COCs were isolated from ovaries of slaughtered gilts and cultured in vitro in M199 supplemented with 5% fetal calf serum. The expression levels of the C-type natriuretic peptide (CNP) precursor ( NPPC ) and its receptor ( NPR2 ) mRNAs during the culture of COCs were determined by real-time RT-PCR. To control the intracellular concentration of cGMP in the COCs, the culture medium was further supplemented with CNP or various concentrations of synthetic cGMP analogues; the concentration of cGMP in COCs was then assessed by ELISA. The effect of the drugs on oocyte maturation was assessed after 24 and 44 h of culture by determining nuclear maturation. The expansion of cumulus cells was assessed by light microscopy and the expression of cumulus expansion-related genes by real-time RT-PCR. A possible effect of cGMP on FSH-induced activation of MAPK3/1 was assessed by immunoblotting the COC proteins with phospho-specific and total anti-Erk1/2 antibodies. Results The COCs expressed NPPC and NPR2 , the key components of cGMP synthesis, and produced a large amount of cGMP upon stimulation with exogenous CNP, which lead to a significant (P  0.05). Conclusions The findings of this study indicate that high cGMP concentrations inhibit the maturation of pig oocytes in vitro but the inhibitory mechanism does not involve the suppression of MAPK3/1 activation in cumulus cells.

Lucie Nemcova - One of the best experts on this subject based on the ideXlab platform.

  • cyclic Guanosine Monophosphate does not inhibit gonadotropin induced activation of mitogen activated protein kinase 3 1 in pig cumulus oocyte complexes
    Reproductive Biology and Endocrinology, 2015
    Co-Authors: Milan Blaha, Lucie Nemcova, Radek Prochazka
    Abstract:

    Background Recent results indicate a key role for cyclic Guanosine Monophosphate (cGMP) in the regulation of oocyte meiotic arrest in preovulatory mammalian follicles. The aim of our study was to determine whether the resumption of oocyte meiosis and expansion of cumulus cells in isolated pig cumulus-oocyte complexes (COCs) can be blocked by a high intracellular concentration of cGMP, and whether this effect is mediated by a cGMP-dependent inhibition of mitogen-activated protein kinase 3/1 (MAPK3/1).

  • Cyclic Guanosine Monophosphate does not inhibit gonadotropin-induced activation of mitogen-activated protein kinase 3/1 in pig cumulus-oocyte complexes
    Reproductive Biology and Endocrinology, 2015
    Co-Authors: Milan Blaha, Lucie Nemcova, Radek Prochazka
    Abstract:

    Background Recent results indicate a key role for cyclic Guanosine Monophosphate (cGMP) in the regulation of oocyte meiotic arrest in preovulatory mammalian follicles. The aim of our study was to determine whether the resumption of oocyte meiosis and expansion of cumulus cells in isolated pig cumulus-oocyte complexes (COCs) can be blocked by a high intracellular concentration of cGMP, and whether this effect is mediated by a cGMP-dependent inhibition of mitogen-activated protein kinase 3/1 (MAPK3/1). Methods The COCs were isolated from ovaries of slaughtered gilts and cultured in vitro in M199 supplemented with 5% fetal calf serum. The expression levels of the C-type natriuretic peptide (CNP) precursor ( NPPC ) and its receptor ( NPR2 ) mRNAs during the culture of COCs were determined by real-time RT-PCR. To control the intracellular concentration of cGMP in the COCs, the culture medium was further supplemented with CNP or various concentrations of synthetic cGMP analogues; the concentration of cGMP in COCs was then assessed by ELISA. The effect of the drugs on oocyte maturation was assessed after 24 and 44 h of culture by determining nuclear maturation. The expansion of cumulus cells was assessed by light microscopy and the expression of cumulus expansion-related genes by real-time RT-PCR. A possible effect of cGMP on FSH-induced activation of MAPK3/1 was assessed by immunoblotting the COC proteins with phospho-specific and total anti-Erk1/2 antibodies. Results The COCs expressed NPPC and NPR2 , the key components of cGMP synthesis, and produced a large amount of cGMP upon stimulation with exogenous CNP, which lead to a significant (P  0.05). Conclusions The findings of this study indicate that high cGMP concentrations inhibit the maturation of pig oocytes in vitro but the inhibitory mechanism does not involve the suppression of MAPK3/1 activation in cumulus cells.

C Yallampalli - One of the best experts on this subject based on the ideXlab platform.

  • Involvement of a nitric oxide-cyclic Guanosine Monophosphate pathway in control of human uterine contractility during pregnancy.
    American journal of obstetrics and gynecology, 1995
    Co-Authors: Irina A. Buhimschi, C Yallampalli, Yuan-lin Dong, R E Garfield
    Abstract:

    Abstract OBJECTIVES: The aims of the study were to investigate whether a nitric oxide-cyclic Guanosine Monophosphate relaxation pathway is present in the human uterus and whether it differentially inhibits contractility during pregnancy and labor. STUDY DESIGN: Myometrial strips were obtained from pregnant women who were either in labor or not in labor and from nonpregnant women. Nitrites and cyclic Guanosine Monophosphate production by the tissues and contractile responses to nitric oxide modifiers were measured. RESULTS: Biochemical assays revealed that nitric oxide (nitrites) and cyclic Guanosine Monophosphate are generated by the human uterus. Cyclic Guanosine Monophosphate production by the uterus was increased by l-arginine (the substrate for nitric oxide) and diethylamine/nitric oxide (a nitric oxide donor) and decreased by nitro-l-arginine methyl ester (an inhibitor of nitric oxide synthase). Spontaneous contractility in vitro was increased by nitro-l-arginine methyl ester and decreased by diethylamine/nitric oxide, which furthermore produced a dose-dependent inhibition of contractility, and the median effective dose of inhibition in tissues from nonlaboring pregnant patients (1.5 ± 0.4 μmol/L) is substantially lower than in tissues from laboring pregnant (21.7 ± 7.4 μmol/L or nonpregnant (20.8 ± 4.4 μmol/L) women. These studies show that the nitric oxide-cyclic quanosine Monophosphate system exists in the human uterus and that it inhibits contractility. Furthermore, the relaxation responsiveness to nitric oxide is elevated during pregnancy and decreased during labor. CONCLUSION: A nitric oxide-cyclic Guanosine Monophosphate relaxation pathway is present in the human uterus and may be responsible for maintaining uterine quiescence during pregnancy. A decrease in uterine relaxation responsiveness to nitric oxide at term may play a role in the initiation of labor.

  • an l arginine nitric oxide cyclic Guanosine Monophosphate system exists in the uterus and inhibits contractility during pregnancy
    American Journal of Obstetrics and Gynecology, 1994
    Co-Authors: C Yallampalli, H Izumi, Mary Byamsmith, R E Garfield
    Abstract:

    Abstract OBJECTIVE: Nitric oxide is synthesized from L -arginine and it causes relaxation of smooth muscle by elevating cyclic Guanosine Monophosphate levels. We hypothesized that an L -arginine–nitric oxide–cGMP system is present in the uterus and modulates contractility. STUDY DESIGN: Isometric tension of the uterus was measured in vitro from pregnant rats in response to various agents that modulate nitric oxide–cyclic Guanosine Monophosphate production or action. RESULTS: Major findings are as follows: (1) The substrate and a donor of nitric oxide produced uterine relaxation; (2) inhibitors of the nitric oxide–cyclic Guanosine Monophosphate pathway blocked the relaxation responses; (3) nitric oxide synthase was localized to several uterine cell types; (4) nitric oxide was produced by the uterus during periods when L-arginine was consumed and citrulline levels increased; (5) effects of nitric oxide substrate on relaxation were mimicked by cyclic Guanosine Monophosphate; (6) nitric oxide–cyclic Guanosine Monophosphate responses were decreased during delivery; (7) L -arginine responses were increased by progesterone, and antiprogesterone treatment decreased cyclic Guanosine Monophosphate – induced relaxations. CONCLUSION: An L -arginine–nitric oxide–cyclic Guanosine Monophosphate system is present in the uterus and it may regulate relaxation during pregnancy. The inhibitory action of L -arginine and 8-bromo-cyclic Guanosine Monophosphate was considerably lower during delivery and post partum, indicating that the nitric oxide system may contribute to the maintenance of uterine quiescence during pregnancy, when progesterone levels are elevated, but not during delivery. (AM J OBSTET GYNECOL 1993;170:175-85.)