The Experts below are selected from a list of 210 Experts worldwide ranked by ideXlab platform

J J Walker - One of the best experts on this subject based on the ideXlab platform.

  • Uterine ultrasonographic changes with Gonadotropin-Releasing Hormone agonists.
    American journal of obstetrics and gynecology, 1999
    Co-Authors: A D Weeks, S R Duffy, J J Walker
    Abstract:

    Our purpose was to assess the changes in uterine volume and uterine artery pulsatility index in response to Gonadotropin-Releasing Hormone agonist treatment in women undergoing hysterectomy for nonfibroid-related uterine bleeding. A double-blind, placebo-controlled randomized trial of 51 women awaiting hysterectomy in a gynecology outpatient clinic was conducted. The women were treated for 8 weeks with either leuprolide acetate depot or placebo. Vaginal ultrasonographic examinations were performed before and after treatment. The paired t test was used for statistical analysis. In those allocated to therapy with Gonadotropin-Releasing Hormone agonist the mean uterine volume decreased by 34% and the uterine artery pulsatility index increased from 2.25 to 2.7. No significant changes were seen in the placebo group. The intersonographer variability was low and there was a high correlation between uterine size as measured by ultrasonography before hysterectomy and that measured postoperatively. Treatment with Gonadotropin-Releasing Hormone agonists leads to uterine shrinkage and an increase in the uterine artery pulsatility index even in the absence of uterine fibroids.

  • Uterine ultrasonographic changes with Gonadotropin-Releasing Hormone agonists.
    American Journal of Obstetrics and Gynecology, 1999
    Co-Authors: Andrew Weeks, Sean Duffy, J J Walker
    Abstract:

    Abstract Objectives: Our purpose was to assess the changes in uterine volume and uterine artery pulsatility index in response to Gonadotropin-Releasing Hormone agonist treatment in women undergoing hysterectomy for nonfibroid-related uterine bleeding. Study Design: A double-blind, placebo-controlled randomized trial of 51 women awaiting hysterectomy in a gynecology outpatient clinic was conducted. The women were treated for 8 weeks with either leuprolide acetate depot or placebo. Vaginal ultrasonographic examinations were performed before and after treatment. The paired t test was used for statistical analysis. Results: In those allocated to therapy with Gonadotropin-Releasing Hormone agonist the mean uterine volume decreased by 34% and the uterine artery pulsatility index increased from 2.25 to 2.7. No significant changes were seen in the placebo group. The intersonographer variability was low and there was a high correlation between uterine size as measured by ultrasonography before hysterectomy and that measured postoperatively. Conclusions: Treatment with Gonadotropin-Releasing Hormone agonists leads to uterine shrinkage and an increase in the uterine artery pulsatility index even in the absence of uterine fibroids. (Am J Obstet Gynecol 1999;180:8-13.)

John H Kehrl - One of the best experts on this subject based on the ideXlab platform.

  • A regulator of G Protein signaling, RGS3, inhibits Gonadotropin-Releasing Hormone (GnRH)-stimulated luteinizing Hormone (LH) secretion
    BMC Cell Biology, 2001
    Co-Authors: Jimmy D Neill, L Wayne Duck, Jeffrey C Sellers, Lois C Musgrove, John H Kehrl
    Abstract:

    Background Luteinizing Hormone secreted by the anterior pituitary gland regulates gonadal function. Luteinizing Hormone secretion is regulated both by alterations in gonadotrope responsiveness to hypothalamic gonadotropin releasing Hormone and by alterations in gonadotropin releasing Hormone secretion. The mechanisms that determine gonadotrope responsiveness are unknown but may involve regulators of G protein signaling (RGSs). These proteins act by antagonizing or abbreviating interaction of Gα proteins with effectors such as phospholipase Cβ. Previously, we reported that gonadotropin releasing Hormone-stimulated second messenger inositol trisphosphate production was inhibited when RGS3 and gonadotropin releasing Hormone receptor cDNAs were co-transfected into the COS cell line. Here, we present evidence for RGS3 inhibition of gonadotropin releasing Hormone-induced luteinizing Hormone secretion from cultured rat pituitary cells. Results A truncated version of RGS3 (RGS3T = RGS3 314–519) inhibited gonadotropin releasing Hormone-stimulated inositol trisphosphate production more potently than did RSG3 in gonadotropin releasing Hormone receptor-bearing COS cells. An RSG3/glutathione-S-transferase fusion protein bound more ^35S-Gqα than any other member of the G protein family tested. Adenoviral-mediated RGS3 gene transfer in pituitary gonadotropes inhibited gonadotropin releasing Hormone-stimulated luteinizing Hormone secretion in a dose-related fashion. Adeno-RGS3 also inhibited gonadotropin releasing Hormone stimulated ^3H-inositol phosphate accumulation, consistent with a molecular site of action at the Gqα protein. Conclusions RGS3 inhibits gonadotropin releasing Hormone-stimulated second messenger production (inositol trisphosphate) as well as luteinizing Hormone secretion from rat pituitary gonadotropes apparently by binding and suppressing the transduction properties of Gqα protein function. A version of RGS3 that is amino-terminally truncated is even more potent than intact RGS3 at inhibiting gonadotropin releasing Hormone-stimulated inositol trisphosphate production.

  • A regulator of G Protein signaling, RGS3, inhibits Gonadotropin-Releasing Hormone (GnRH)-stimulated luteinizing Hormone (LH) secretion
    BMC cell biology, 2001
    Co-Authors: Jimmy D Neill, L Wayne Duck, Jeffrey C Sellers, Lois C Musgrove, John H Kehrl
    Abstract:

    Luteinizing Hormone secreted by the anterior pituitary gland regulates gonadal function. Luteinizing Hormone secretion is regulated both by alterations in gonadotrope responsiveness to hypothalamic gonadotropin releasing Hormone and by alterations in gonadotropin releasing Hormone secretion. The mechanisms that determine gonadotrope responsiveness are unknown but may involve regulators of G protein signaling (RGSs). These proteins act by antagonizing or abbreviating interaction of Gα proteins with effectors such as phospholipase Cβ. Previously, we reported that gonadotropin releasing Hormone-stimulated second messenger inositol trisphosphate production was inhibited when RGS3 and gonadotropin releasing Hormone receptor cDNAs were co-transfected into the COS cell line. Here, we present evidence for RGS3 inhibition of gonadotropin releasing Hormone-induced luteinizing Hormone secretion from cultured rat pituitary cells. A truncated version of RGS3 (RGS3T = RGS3 314–519) inhibited gonadotropin releasing Hormone-stimulated inositol trisphosphate production more potently than did RSG3 in gonadotropin releasing Hormone receptor-bearing COS cells. An RSG3/glutathione-S-transferase fusion protein bound more 35S-Gqα than any other member of the G protein family tested. Adenoviral-mediated RGS3 gene transfer in pituitary gonadotropes inhibited gonadotropin releasing Hormone-stimulated luteinizing Hormone secretion in a dose-related fashion. Adeno-RGS3 also inhibited gonadotropin releasing Hormone stimulated 3H-inositol phosphate accumulation, consistent with a molecular site of action at the Gqα protein. RGS3 inhibits gonadotropin releasing Hormone-stimulated second messenger production (inositol trisphosphate) as well as luteinizing Hormone secretion from rat pituitary gonadotropes apparently by binding and suppressing the transduction properties of Gqα protein function. A version of RGS3 that is amino-terminally truncated is even more potent than intact RGS3 at inhibiting gonadotropin releasing Hormone-stimulated inositol trisphosphate production.

Mark A Lawson - One of the best experts on this subject based on the ideXlab platform.

  • Insulin augments Gonadotropin-Releasing Hormone induction of translation in LbetaT2 cells.
    Molecular and cellular endocrinology, 2009
    Co-Authors: Amy M Navratil, Hyunjin Song, Jeniffer B Hernandez, Brian D Cherrington, Sharon J Santos, Janine M Low, Mark A Lawson
    Abstract:

    The integrated signaling of insulin and Gonadotropin-Releasing Hormone in the pituitary gonadotropes may have a profound bearing on reproductive function, although the cross-receptor signaling mechanisms are unclear. We demonstrate that the insulin receptor is constitutively localized to non-caveolar lipid raft microdomains in the pituitary gonadotrope cell line LbetaT2. The localization to rafts is consistent with similar localization of the GnRH receptor. Insulin receptor phosphorylation occurs in raft domains and activates the downstream signaling targets Insulin Receptor Substrate1 and Akt/Protein Kinase B. Although insulin alone does not strongly activate the extracellular signal-regulated kinase second messenger cascade, co-stimulation potentiates the phosphorylation of the extracellular signal-regulated kinase by Gonadotropin-Releasing Hormone. The co-stimulatory effect of insulin and Gonadotropin-Releasing Hormone is also evident in increased activation of cap-dependent translation. In contrast, co-stimulation attenuates Akt/Protein Kinase B activation. Our results show that both Gonadotropin-Releasing Hormone and insulin are capable of mutually altering their respective regulatory signaling cascades. We suggest that this provides a mechanism to integrate neuropeptide and energy homeostatic signals to modulate reproductive function.

  • Insulin augments Gonadotropin-Releasing Hormone induction of translation in LβT2 cells
    Molecular and Cellular Endocrinology, 2009
    Co-Authors: Amy M Navratil, Hyunjin Song, Jeniffer B Hernandez, Brian D Cherrington, Sharon J Santos, Janine M Low, Mark A Lawson
    Abstract:

    The integrated signaling of insulin and Gonadotropin-Releasing Hormone in the pituitary gonadotropes may have a profound bearing on reproductive function, although the cross-receptor signaling mechanisms are unclear. We demonstrate that the insulin receptor is constitutively localized to non-caveolar lipid raft microdomains in the pituitary gonadotrope cell line LβT2. The localization to rafts is consistent with similar localization of the GnRH receptor. Insulin receptor phosphorylation occurs in raft domains and activates the downstream signaling targets Insulin Receptor Substrate1 and Akt/Protein Kinase B. Although insulin alone does not strongly activate the extracellular signal-regulated kinase second messenger cascade, co-stimulation potentiates the phosphorylation of the extracellular signal-regulated kinase by Gonadotropin-Releasing Hormone. The co-stimulatory effect of insulin and Gonadotropin-Releasing Hormone is also evident in increased activation of cap-dependent translation. In contrast, co-stimulation attenuates Akt/Protein Kinase B activation. Our results show that both Gonadotropin-Releasing Hormone and insulin are capable of mutually altering their respective regulatory signaling cascades. We suggest that this provides a mechanism to integrate neuropeptide and energy homeostatic signals to modulate reproductive function.

Gary D. Hodgen - One of the best experts on this subject based on the ideXlab platform.

  • New trends in combined use of Gonadotropin-Releasing Hormone antagonists with gonadotropins or pulsatile Gonadotropin-Releasing Hormone in ovulation induction and assisted reproductive technologies.
    Current opinion in obstetrics & gynecology, 1992
    Co-Authors: Keith Gordon, Douglas R. Danforth, Robert F. Williams, Gary D. Hodgen
    Abstract:

    The use of Gonadotropin-Releasing Hormone agonists as adjunctive therapy with gonadotropins for ovulation induction in in vitro fertilization and other assisted reproductive technologies has become common clinical practice. With the recent advent of potent Gonadotropin-Releasing Hormone antagonists free from the marked histamine-release effects that stymied earlier compounds, an attractive alternative method may be available. We have established the feasibility of combining Gonadotropin-Releasing Hormone antagonist-induced inhibition of endogenous gonadotropins with exogenous gonadotropin therapy for ovulation induction in a nonhuman primate model. Here, the principal benefits to be gained from using the Gonadotropin-Releasing Hormone antagonist rather than the Gonadotropin-Releasing Hormone agonist are the immediate inhibition of pituitary gonadotropin secretion without the "flare effect," which brings greater safety and convenience for patients and the medical team and saves time and money. We have also recently demonstrated the feasibility of combining Gonadotropin-Releasing Hormone antagonist with pulsatile Gonadotropin-Releasing Hormone therapy for the controlled restoration of gonadotropin secretion and gonadal steroidogenesis culminating in apparently normal (singleton) ovulatory cycles. This is feasible only with Gonadotropin-Releasing Hormone antagonists because, unlike Gonadotropin-Releasing Hormone agonists, they achieve control of the pituitary-ovarian axis without down regulation of the Gonadotropin-Releasing Hormone receptor system. This capacity to override Gonadotropin-Releasing Hormone antagonist-induced suppression of pituitary-ovarian function may allow new treatment modalities to be employed for women who suffer from chronic hyperandrogenemia with polycystic ovarian disease.

Jimmy D Neill - One of the best experts on this subject based on the ideXlab platform.

  • A regulator of G Protein signaling, RGS3, inhibits Gonadotropin-Releasing Hormone (GnRH)-stimulated luteinizing Hormone (LH) secretion
    BMC Cell Biology, 2001
    Co-Authors: Jimmy D Neill, L Wayne Duck, Jeffrey C Sellers, Lois C Musgrove, John H Kehrl
    Abstract:

    Background Luteinizing Hormone secreted by the anterior pituitary gland regulates gonadal function. Luteinizing Hormone secretion is regulated both by alterations in gonadotrope responsiveness to hypothalamic gonadotropin releasing Hormone and by alterations in gonadotropin releasing Hormone secretion. The mechanisms that determine gonadotrope responsiveness are unknown but may involve regulators of G protein signaling (RGSs). These proteins act by antagonizing or abbreviating interaction of Gα proteins with effectors such as phospholipase Cβ. Previously, we reported that gonadotropin releasing Hormone-stimulated second messenger inositol trisphosphate production was inhibited when RGS3 and gonadotropin releasing Hormone receptor cDNAs were co-transfected into the COS cell line. Here, we present evidence for RGS3 inhibition of gonadotropin releasing Hormone-induced luteinizing Hormone secretion from cultured rat pituitary cells. Results A truncated version of RGS3 (RGS3T = RGS3 314–519) inhibited gonadotropin releasing Hormone-stimulated inositol trisphosphate production more potently than did RSG3 in gonadotropin releasing Hormone receptor-bearing COS cells. An RSG3/glutathione-S-transferase fusion protein bound more ^35S-Gqα than any other member of the G protein family tested. Adenoviral-mediated RGS3 gene transfer in pituitary gonadotropes inhibited gonadotropin releasing Hormone-stimulated luteinizing Hormone secretion in a dose-related fashion. Adeno-RGS3 also inhibited gonadotropin releasing Hormone stimulated ^3H-inositol phosphate accumulation, consistent with a molecular site of action at the Gqα protein. Conclusions RGS3 inhibits gonadotropin releasing Hormone-stimulated second messenger production (inositol trisphosphate) as well as luteinizing Hormone secretion from rat pituitary gonadotropes apparently by binding and suppressing the transduction properties of Gqα protein function. A version of RGS3 that is amino-terminally truncated is even more potent than intact RGS3 at inhibiting gonadotropin releasing Hormone-stimulated inositol trisphosphate production.

  • A regulator of G Protein signaling, RGS3, inhibits Gonadotropin-Releasing Hormone (GnRH)-stimulated luteinizing Hormone (LH) secretion
    BMC cell biology, 2001
    Co-Authors: Jimmy D Neill, L Wayne Duck, Jeffrey C Sellers, Lois C Musgrove, John H Kehrl
    Abstract:

    Luteinizing Hormone secreted by the anterior pituitary gland regulates gonadal function. Luteinizing Hormone secretion is regulated both by alterations in gonadotrope responsiveness to hypothalamic gonadotropin releasing Hormone and by alterations in gonadotropin releasing Hormone secretion. The mechanisms that determine gonadotrope responsiveness are unknown but may involve regulators of G protein signaling (RGSs). These proteins act by antagonizing or abbreviating interaction of Gα proteins with effectors such as phospholipase Cβ. Previously, we reported that gonadotropin releasing Hormone-stimulated second messenger inositol trisphosphate production was inhibited when RGS3 and gonadotropin releasing Hormone receptor cDNAs were co-transfected into the COS cell line. Here, we present evidence for RGS3 inhibition of gonadotropin releasing Hormone-induced luteinizing Hormone secretion from cultured rat pituitary cells. A truncated version of RGS3 (RGS3T = RGS3 314–519) inhibited gonadotropin releasing Hormone-stimulated inositol trisphosphate production more potently than did RSG3 in gonadotropin releasing Hormone receptor-bearing COS cells. An RSG3/glutathione-S-transferase fusion protein bound more 35S-Gqα than any other member of the G protein family tested. Adenoviral-mediated RGS3 gene transfer in pituitary gonadotropes inhibited gonadotropin releasing Hormone-stimulated luteinizing Hormone secretion in a dose-related fashion. Adeno-RGS3 also inhibited gonadotropin releasing Hormone stimulated 3H-inositol phosphate accumulation, consistent with a molecular site of action at the Gqα protein. RGS3 inhibits gonadotropin releasing Hormone-stimulated second messenger production (inositol trisphosphate) as well as luteinizing Hormone secretion from rat pituitary gonadotropes apparently by binding and suppressing the transduction properties of Gqα protein function. A version of RGS3 that is amino-terminally truncated is even more potent than intact RGS3 at inhibiting gonadotropin releasing Hormone-stimulated inositol trisphosphate production.