Gonadotropin-releasing peptide from human follicular fluid: isolation, characterization, and chemical synthesis.

Li, Choh Hao; Ramasharma, K.; Yamashiro, Donald; Chung, Doug Young

doi:10.1073/pnas.84.4.959

Cited by 25 publications

(6 citation statements)

References 21 publications

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“…Previous studies have shown that placental tissue restores Boyle, 1997). Furthermore, other GnRH-like factors are present in human reproductive tissues (Li et al, 1987), and post-its ability to store HCG within a short time and specific HCG storage granules appear in first trimester placenta, but not in translationally modified forms of GnRH are active in the human placenta (Gautron et al, 1981(Gautron et al, , 1992Currie et al, 1993). term placentae (Morrish et al, 1987).…”

Section: Discussionmentioning

confidence: 99%

Comparison of the effects of GnRH-I and GnRH-II on HCG synthesis and secretion by first trimester trophoblast

Islami

Chardonnens

Campana

et al. 2001

Molecular Human Reproduction

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Gonadotrophin-releasing hormone (GnRH) is an important factor in the regulation of the synthesis and secretion of gonadotrophins from the pituitary gland. An isoform of this decapeptide, GnRH-II, with an amino acid sequence 70% homologous to GnRH-I, has been recently described. Since the physiological effects of GnRH-II are not yet known, we undertook the present study to see whether GnRH-II could be involved in the secretion and synthesis of HCG in first trimester trophoblast. We incubated cytotrophoblastic cells (CTB) with GnRH-I or GnRH-II, for 4 or 96 h and collected the media at different times thereafter. We also performed experiments with placental tissue, where GnRH-I or GnRH-II was added to perifused placental explants, and samples were collected every 3 min. Total amounts of human chorionic gonadotrophin (HCG) were measured in all samples by enzyme-linked immunosorbent assay. GnRH-I was more potent than GnRH-II when incubated for 4 h with CTB, as indicated by increased HCG secretion at 8 h and at 24 h. GnRH-I, but not GnRH-II, down-regulated HCG secretion when incubated for 96 h. GnRH-I significantly increased HCG secretion by the explants, while GnRH-II had a lesser effect. Both induced a pulse of HCG immediately after their injection. Our data show that GnRH-I has more effect than GnRH-II on HCG synthesis and secretion. This difference could be explained by different pathways of GnRH degradation, different receptor affinities, or even by different types of placental GnRH receptor.

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Section: Discussionmentioning

confidence: 99%

Comparison of the effects of GnRH-I and GnRH-II on HCG synthesis and secretion by first trimester trophoblast

Islami

Chardonnens

Campana

et al. 2001

Molecular Human Reproduction

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“…Considering the high concentrations of GnRHa needed for a significant response in our study, it is therefore unlikely that circulating nat¬ ural GnRH, or even circulating GnRHa after phar¬ macological administration, can affect human gran¬ ulosa cells through a direct ovarian effect in vivo (17). It is more likely that the effects of GnRHa observed in this study, as well as in the study by Tureck et al (7) represent actions normally ex¬ pressed by endogenously produced GnRH-like peptides (18,19) of importance for follicular devel¬ opment and maturation.…”

Section: Discussionmentioning

confidence: 76%

Effects of a gonadotropin-releasing hormone agonist on progesterone formation in cultured human granulosa cells

Olsson

Åkesson²,

Hillensjø³

1990

Acta Endocrinologica

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Human granulosa cells from follicles of natural cycles (13 women) in mid-or late follicular phase were cultured in modified . Human luteinizing hormone (100 \g=m\g/l ),follicle-stimulating hormone (100 \g=m\g/l) and gonadotropin-releasing hormone agonist (GnRHa) (10\m=-\12 to 10\m=-\6 mol/l) alone or in combination were added to the culture medium. Medium content of progesterone was analysed. In granulosa cells obtained in the mid-follicular phase, the basal progesterone formation averaged 0.5 pg \ m=. \ cell\m=-\ 1 \ m=. \ (48 h)\m=-\ 1\ m=. \ FSH caused a 3-fold stimulation. GnRHa (10\m=-\6mol/l) had a variable influence on the basal progesterone formation, whereas it consistently inhibited (40-50%) the FSH response. In granulosa cells from late follicular phase basal progesterone formation averaged 5 pg \ m=. \ cell\m=-\\m=.\(48 h)\m=-\1 and was stimulated 3\ x =r eq-\ to 6-fold by LH. GnRHa (10\m=-\6mol/l) stimulated the basal progesterone formation and caused a tended to potentiate the LH response on progesterone formation. It is concluded that GnRHa at relatively high concentrations exerts direct effects on gonadotropin-stimulated progesterone formation of human granulosa cells and that these effects are different (inhibitory or stimulatory) dependent on the degree of follicular maturation, and/or type of gonadotropin used.Gonadotropin-releasing hormone is the natural hypothalamic decapeptide which regulates the syn¬ thesis and secretion of the gonadotropins from the pituitary gland. Synthetic GnRH as well as agonistic analogues of GnRH (GnRHa) have been used clin¬ ically for two basically different purposes: 1. Treat¬ ment of certain forms of amenorrhea, in which case the pulsatile administration of physiological doses of GnRH are used (1). 2. As new contraceptive agents, in which case administration of pharmacological doses of potent GnRHa causes inhibition of ovarian function (2). 3. Down-regulation of pitu¬ itary-ovarian function prior to hyperStimulation with exogenous gonadotropins in the course of in vitro fertilization/embryo transfer (3). These »par¬ adoxical« inhibitory effects by pharmacological GnRHa treatment are probably largely due to down-regulation of pituitary GnRH receptors, di¬ minished secretion of gonadotropins and, second¬ arily, inhibition of ovarian function. A direct inhib¬ itory effect on the ovary by GnRHa can, however, not be ruled out.In the rat, administration of GnRH at pharma¬ cological doses has been shown to have direct ef¬ fects on the ovary both in vivo and in vitro. These effects are elicited by specific high-affinity recep¬ tors in the gonad and include short-term stimula¬ tory effects on ovulation, oocyte maturation, steroidogenesis, and prostaglandin synthesis (4), as well as long-term inhibitory effects on follicular de¬ velopment, gonadotropin receptors, and steroidogenesis (5,6).A similar direct GnRH effect has been consid¬ ered for the human ovary but the experimental results, so far, are contradictory. In cultured human granulosa cells obtained from natural cycl...

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“…79,80 Since high-affinity GnRH binding sites are not detectable in either GnRH: <<Glu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH 2 hF-GRP: H-Thr-Asp-Thr-Ser-His-His-Asp-Gln-Asp-His-Pro-Thr-Phe-Asn-OH Figure 1. Comparison of the primary structures of GnRH and human follicular gonadotropin-releasing peptide (hF-GRP), as described in Li et al 82 ovine or bovine ovarian tissue, 46 future studies will be required to determine the significance of these ovarian GnRH-like proteins. A related issue that requires clarification is the observation that GnRH produces a biologic response in porcine granulosa cells, 34 a tissue that also lacks high-affinity GnRH binding sites.…”

Section: Production Of Ovarian Gonadotropin-releasing Hormonementioning

confidence: 99%

“…Using this approach, GnRH-like activity was detected that is similar to the material found in rat, ovine, and bovine ovaries, and distinct from hypothalamic GnRH. In another study, 82 follicular fluid, obtained from women undergoing fertility examination, was acidified and fractionated by Sephadex chromatography and high-pressure liquid chromatography. Fifty milliliters of follicular fluid yielded 300 µg of a peptide with a primary structure that is distinct from the sequence of hypothalamic GnRH (Fig.…”

Section: Production Of Ovarian Gonadotropin-releasing Hormonementioning

confidence: 99%

“…At this time, it is not possible to compare the GnRH-like activity of human follicular and luteal tissue with hF-GRP. However, the observation that hF-GRP is biologically active in a rat pituitary cell culture assay 82 and the fact that GnRH shows similar efficacies in rat pituitary and ovarian tissue indicate that hF-GRP should be effective in the rat ovarian membrane GnRH radioreceptor assay.…”

Section: Production Of Ovarian Gonadotropin-releasing Hormonementioning

confidence: 99%

See 1 more Smart Citation

Potential Relevance of Gonadotropin-Releasing Hormone to Ovarian Physiology

Jones¹

1989

Semin Reprod Med

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Gonadotropin-releasing peptide from human follicular fluid: isolation, characterization, and chemical synthesis.

Cited by 25 publications

References 21 publications

Comparison of the effects of GnRH-I and GnRH-II on HCG synthesis and secretion by first trimester trophoblast

Comparison of the effects of GnRH-I and GnRH-II on HCG synthesis and secretion by first trimester trophoblast

Effects of a gonadotropin-releasing hormone agonist on progesterone formation in cultured human granulosa cells

Potential Relevance of Gonadotropin-Releasing Hormone to Ovarian Physiology

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