SEARCH · PubMed Health

Results for “GnRH antagonist”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources

PubMed2000

Embryo implantation and GnRH antagonists: GnRH antagonists do not activate the GnRH receptor.

Recent suggestions that gonadotrophin-releasing hormone (GnRH) antagonists activate the GnRH receptor are discussed. Most of the studies cited in support of this suggestion are in-vitro studies, testing supra-pharmacological doses of GnRH analogues in cancer cell lines, whereas GnRH antagonists, e.g. ganirelix or cetrorelix, do not affect the steroidogenesis of human granulosa cells in vitro. In patients treated with GnRH antagonists prior to IVF or intracytoplasmic sperm injection (ICSI), oocyte maturity and fertilization rates are equal to those achieved following a long protocol of GnRH agonists. Although there is a tendency towards a lower pregnancy rate (not statistically significant) in the initial trials using GnRH antagonist with either recombinant FSH or human menopausal gonadotrophin (HMG) for ovarian stimulation, this new treatment option of GnRH antagonists facilitates short and simple treatment and improves the convenience and safety for the patient. As with GnRH agonists in the past, the clinical outcome of GnRH antagonist treatment will improve with time as more clinical experience is gained (learning curve) and the treatment protocol is optimized. Moreover, a GnRH agonist instead of human chorionic gonadotrophin (HCG) may be used for triggering ovulation and will decrease the cancellation rate and minimize the risk for developing ovarian hyperstimulation syndrome (OHSS).

Female↗

PubMed2000

Embryo implantation and GnRH antagonists: GnRH antagonists in ART: lower embryo implantation?

Recently, concerns have been raised regarding possible adverse effects of gonadotrophin-releasing hormone (GnRH) antagonists on extra-pituitary reproductive cells and organs, i.e. ovarian cells, oocyte, embryo, endometrium. These concerns are based on numerous in-vitro studies suggesting decreased biosynthesis of growth factors caused by local action of GnRH antagonists. Clinically, it has been shown that the use of high doses (< or =1 mg daily) of GnRH antagonists is associated with low implantation rates in IVF. Although such direct adverse effect of GnRH antagonists cannot be ruled out at this time, so far clinical experience points to profound LH suppression as the major caveat associated with the use of high doses of GnRH antagonists. Very low LH concentrations are associated with aberrant concentrations of oestradiol during ovarian stimulation, which may in turn adversely effect implantation potential. The clinical data available thus far on the use of GnRH antagonists originate from protocols designed for clinical studies. It is predicted that as more clinical experience is gained, and with protocol modifications to suit individual patient response, GnRH antagonists will be comparable with the agonists in terms of cycle outcome.

Embryo Implantation↗

PubMed1984

Effect of treatment with GnRH antagonist, GnRH antiserum and bromocriptine on pituitary-testicular function of adult rats.

Gonadotropin secretion of adult male rats was inhibited by one-week treatment with a GnRH antagonist analogue (N-acetyl-Ala1,D-p-Cl-Phe2,D-Trp3,6-GnRH, Ant.) or a GnRH antiserum (A/S). Since Ant. but not A/S binds to GnRH receptors (R), it was expected that comparison of the two treatment regimes would elucidate a physiological role for testicular GnRH-R. Furthermore, the effect of combined gonadotropin and prolactin deficiency was studied in rats treated with Ant. and bromocriptine (BR). Available pituitary GnRH-R were decreased by both Ant. and A/S (P less than 0.01), but not by BR. Testicular content of free GnRH-R was decreased by Ant. by 70-80% (P less than 0.01), probably owing to occupancy, but A/S and BR had no effect on these binding sites. Serum LH and FSH fell by about 75% with Ant. and A/S treatments (P less than 0.01), and Prl by 90% with BR (P less than 0.01). Intratesticular testosterone (T) decreased significantly with Ant. and A/S treatment (P less than 0.01-0.05), but was unaffected by BR. Only Ant. and BR treatments together, but neither alone, were able to suppress Leydig cell capacity to produce T in vitro. Relative blockade of C21 steroid side-chain cleavage by Ant. and A/S was suggested by elevated progesterone (P) and/or P/T ratios in the serum and testis tissues. Ant. and A/S had no effect on testicular LH and FSH-R, but both decreased testicular Prl-R by about 50% (P less than 0.01-0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1984

Pituitary-testicular function in immature rats after treatment with GnRH antagonist, GnRH antiserum and bromocriptine.

The effects of a GnRH antagonist analogue (N-acetyl-Ala1,D-p-Cl-Phe2,D-Trp3,6-GnRH, Ant.) and a GnRH antiserum (A/S) on the development of pituitary-testicular function were studied in immature (23/24-31/32-day-old) rats. In another experiment the Ant. treatment was combined with bromocriptine (BR)-induced hypoprolactinaemia. Ant. and A/S decreased serum and pituitary levels of LH and FSH, and BR those of Prl (P less than 0.01-0.05). Testicular testosterone (T) and progesterone (P) contents were significantly decreased only by Ant. (P less than 0.01). Ant. decreased the weights of the testes, ventral prostates and seminal vesicles, as well as testicular LH, FSH and Prl receptors (R) (P less than 0.01-0.05). BR decreased LH-R but had no effect on Prl-R. Both Ant. and A/S decreased available pituitary GnRH-R (P less than 0.01), but free testicular GnRH-R were reduced only by Ant. BR increased GnRH receptors in the pituitaries. It is concluded that Ant.-induced low gonadotropin levels in immature animals inhibit the developmental increase of testicular weight, gonadotropin and Prl-R, steroidogenesis and androgen action on accessory sex glands. Hypoprolactinaemia had an additive inhibitory effect to the antigonadal effects of Ant. The testis tissue of immature (23/24-day-old) animals already contains GnRH-R. In general, developing animals are clearly very sensitive to the antigonadal actions of Ant. and BR, whereas the effect of GnRH-A/S is less pronounced than in adults.

Animals↗

PubMed2005

Comparison of a gonadotropin-releasing hormone (GnRH) antagonist and GnRH agonist flare-up regimen in poor responders undergoing ovarian stimulation.

OBJECTIVE: To compare the efficacy of flare-up and GnRH-antagonist treatment in poor-responder patients. DESIGN: Randomized prospective study. SETTING: Assisted reproduction center. PATIENT(S): Fifty-five poor-responder patients undergoing intracytoplasmic sperm injection (ICSI). INTERVENTION(S): Thirty patients received GnRH agonist on the 1st day of menstruation, followed by exogenous gonadotropins from the 2nd day. Twenty-five patients received exogenous gonadotropins starting on the second day of menstruation, followed by GnRH antagonist when the leading follicle reached 14 mm in diameter. MAIN OUTCOME MEASURE(S): The total dose of FSH administered during the ovarian stimulation, as well as the number of mature oocytes retrieved, embryo quality, fertilization, implantation, and pregnancy rates were evaluated. RESULT(S): The number of ampules and units of FSH administered were significantly less in the flare-up than in the antagonistic group. The numbers of mature oocytes retrieved and of top-quality embryos transferred were significantly greater in the flare-up than in the GnRH-antagonist group. The fertilization rate (84% vs. 63%) was significantly higher in the flare-up than in the GnRH-antagonist group. The implantation and pregnancy rate were similar in the two groups. CONCLUSION(S): The flare-up protocol appears to be more effective than the GnRH-antagonist protocol in terms of mature oocytes retrieved, fertilization rate, and top-quality embryos transferred in poor-responder patients.

Adult↗

PubMed1997

Comparing the clinical utility of GnRH antagonist to GnRH agonist in an oocyte donation program.

A potent gonadotropin-releasing hormone (GnRH) antagonist (Nal-Glu) was administered to downregulate the pituitaries of oocyte donors (n = 15) and block their midcycle luteinizing hormone surges. Donors received Nal-Glu at a dose of 50 microg/kg/day i.m., beginning when lead follicles reached a mean diameter of 14 mm. All donors had previously undergone controlled ovarian hyperstimulation cycles using GnRH agonist (leuprolide acetate) administered subcutaneously beginning during the midluteal phase. Ovarian stimulation was performed using human menopausal gonadotropin (hMG). Compared to previous stimulated cycles using agonist and hMG, cycles with antagonist and hMG demonstrated a significant decrease in the amount of hMG required for follicle stimulation (24.7 +/- 1.8 vs. 31.3 +/- 2.5 ampules; p < 0.05). There was also a significant reduction in the number of patient visits necessary per cycle (5.1 +/- 1.4 vs. 9.3 +/- 1.1; p < 0.05) and the required duration of treatment to accomplish a cycle (27.1 +/- 5.3 vs. 11.3 +/- 1.3 days; p < 0.05). However, there were no differences noted in the number of oocytes retrieved (10.7 +/- 4.5 vs. 13.0 +/- 6.3), the fertilization rate of oocytes (60.3 +/- 10.2 vs. 53.9 +/- 11.6%), or the number of embryos obtained per recipient (5.5 +/- 3.2 vs. 7.6 +/- 5.3). Clinical pregnancies occurred in 7 of 15 transfer cycles to recipients. There were no serious adverse side effects experienced by donors using antagonist. We conclude that the use of GnRH antagonist significantly reduces the amount of medication and the time required for ovarian hyperstimulation and that is a useful adjunct in cycling oocyte donors.

Adult↗

PubMed2001

Embryo implantation and GnRH antagonists: ovarian actions of GnRH antagonists.

The gonadotrophin-releasing hormone (GnRH) antagonists, cetrorelix and ganirelix, have both been approved for ovarian stimulation to prevent a premature LH surge. Since GnRH receptors and their gene expression have been detected in human ovary, concern has risen over whether GnRH antagonists might affect ovarian function. Three large trials which compared GnRH agonists (used in the standard protocol worldwide), with the new antagonist treatment found no significant differences concerning the most important goals, e.g. pregnancy rate, fertilization and quality of oocytes. However, the concentration of oestradiol, and the pregnancy and implantation rates were lower in GnRH antagonist-treated patients. These findings again fuelled the debate about the possible extrapituitary effects of GnRH antagonists. Here, we review the conflicting data in the literature on the ovarian effects of GnRH antagonists and discuss our own results. In our view, it is unlikely that GnRH antagonists have a relevant impact on ovarian steroidogenesis and function; however, GnRH antagonists may exert other effects on the ovary.

Animals↗

PubMed1982

A gonadotrophin-releasing hormone (GnRH) antagonist inhibits GnRH- but not LH-induced meiosis in follicle-enclosed rat oocytes in vitro.

Previous studies have shown that gonadotrophin-releasing hormone (GnRH) can induce resumption of meiosis in follicle-enclosed rat oocytes. In the present study a GnRH antagonistic analogue ([D-pGlul,D-Phe2,-D-Trp3,6]LRF) was found to effectively abolish the stimulatory effect of a GnRH agonist upon resumption of meiosis and lactate accumulation in isolated pre-ovulatory rat follicles but the have no effect on LH stimulation of these parameters. It is concluded that although LH and GnRH can evoke a similar response they act through separate receptor sites and that it is unlikely that GnRH mediates the effect of LH on meiosis or glycolysis.

Animals↗

PubMed2003

Gonadotropin-releasing hormone (GnRH)-antagonist versus GnRH-agonist in ovarian stimulation of poor responders undergoing IVF.

PURPOSE: The objective of this study was to compare the efficacy of GnRH-antagonists to GnRH-agonists in ovarian stimulation of poor responders undergoing IVF. METHODS: Retrospective analysis of our data revealed that 56 patients underwent treatment with a GnRH-agonist according to the flare-up protocol. Patients failing to achieve an ongoing pregnancy (n = 53) were subsequently treated in the next cycle with a GnRH-antagonist according to the multiple-dose protocol. Main outcome measures included the clinical pregnancy and implantation rates. RESULTS: While ovulation induction characteristics and results did not differ between the two protocols, the number of embryos transferred was significantly higher (P = 0.046) in the GnRH-antagonist than in the GnRH-agonist stimulation protocol (2.5 +/- 1.6 vs. 2.0 +/- 1.4, respectively). The clinical pregnancy and implantation rates per transfer in the GnRH-antagonist group appeared higher than in the GnRH-agonist, but did not differ statistically (26.1 and 10.7 compared with 12.2 and 5.9%, respectively). However, the ongoing pregnancy rate per transfer was statistically significantly higher (P = 0.03) in the GnRH-antagonist than in the GnRH-agonist group (23.9 vs. 7.3%, respectively). CONCLUSION: Applying GnRH-antagonists to ovarian stimulation protocols may offer new hope for IVF poor responder patients. However, further controlled randomized prospective studies with larger sample sizes are required to establish these results.

Adult↗

PubMed2005

GnRH antagonist in IVF poor-responder patients: results of a randomized trial.

The aim of this prospective study was to evaluate the efficacy of gonadotrophin-releasing hormone antagonist (GnRH) in comparison with the standard long protocol in poor-responder patients. Sixty patients with poor ovarian response in previous treatment cycles were randomized into two groups: group A (n = 30) was stimulated with a standard long protocol, and group B (n = 30) received GnRH antagonist. Vaginal ultrasound was performed to evaluate ovarian response. There was a significantly reduced duration of ovarian stimulation (9.8 +/- 0.8 versus 14.6 +/- 1.2, P = 0.001) in group B in comparison with group A, and a reduced number of ampoules was used in group B (49.3 +/- 4.3 versus 72.6 +/- 6.8, P = 0.0001). In group B, the number of oocytes retrieved was significantly higher than in group A (5.6 +/- 1.6 versus 4.3 +/- 2.2, P = 0.02) and there was an increased number of follicles with a diameter >15 mm at human chorionic gonadotrophin administration in group B (P = 0.0001). Fewer cycles were cancelled with the use of an antagonist protocol. Five pregnancies (17% for embryo transfer) were obtained with GnRH antagonist protocol and two (7% for embryo transfer) with GnRH agonist protocol.

Adult↗

PubMed2000

Embryo implantation and GnRH antagonists: embryo implantation: the Rubicon for GnRH antagonists.

When gonadotrophin-releasing hormone (GnRH) was discovered, the agonist and antagonist of GnRH were developed to control the release of FSH and LH by the gonadotrophs. More than 10 years of research were needed to develop a GnRH antagonist free of histamine release. Recent studies have shown that these GnRH antagonists are effective in preventing a rise in LH during ovarian stimulation in IVF. However, a decrease in ongoing pregnancies seems to suggest that implantation rates per transferred embryo are reduced in GnRH antagonist-stimulated cycles. In my opinion, these data highlight an area less well known to clinicians: the role of the GnRH antagonist at the cellular level in extrapituitary tissues. There are sufficient data in the literature suggesting that GnRH antagonist is an inhibitor of the cell cycle by decreasing the synthesis of growth factors. Given that, for folliculogenesis, blastomere formation and endometrium development, mitosis is everything; the interaction between the GnRH antagonist and the GnRH receptor (present in all these cells and tissues) may compromise the mitotic programme of these cells. This is the Rubicon for the GnRH antagonist: to demonstrate irrevocably that, at the minimal doses necessary to suppress LH release, it does not affect processes such as implantation, embryo development and folliculogenesis.

Animals↗

PubMed2000

Comparison of cryopreservation outcome with human pronuclear stage oocytes obtained by the GnRH antagonist, cetrorelix, and GnRH agonists.

This retrospective study was performed to examine the implantation and pregnancy rates of frozen-thawed pronuclear stage oocytes obtained with the use of a GnRH antagonist, Cetrorelix (Cetrotide((R)) ASTA-Medica, Frankfurt/M, Germany) used in a multidose protocol with hMG, and to compare these results with those obtained after a conventional long GnRH analogue protocol (Decapeptyl-Depot, Ferring, Kiel, Germany). The study population consisted of 31 infertile couples with frozen-thawed pronuclear stage oocytes after ICSI treatment using the GnRH antagonist Cetrorelix (Cetrorelix((R))) and 31 infertile couples with frozen-thawed pronuclear stage oocytes after ICSI treatment using the long GnRH analogue protocol. Patients underwent ICSI after down regulation with a GnRH agonist (Decapeptyl) and stimulation with hMG, or a GnRH antagonist (Cetrorelix) and hMG. The supernumerary pronuclear stage oocytes were cryopreserved and transferred in a later mildly stimulated cycle. The implantation and pregnancy rates for frozen-thawed pronuclear stage oocytes derived from the GnRH antagonist compared with the GnRH agonist were 3.26% versus 3.73% (P=1.0000) and 8.33% versus 10.25% (P=1.0000), respectively. To our knowledge we report here the first pregnancies obtained by the transfer of cryopreserved pronuclear stage embryos generated from ICSI using a GnRH antagonist in the collecting cycle. The use of Cetrorelix in a multiple dose protocol in combination with hMG does not demonstrate a negative effect on viability, implantation potential or pregnancy outcome as compared to 2PN conceptuses obtained from a long GnRH agonist-hMG protocol.

Abortion, Spontaneous↗

PubMed2006

Comparison between a GnRH antagonist and a GnRH agonist flare-up protocol in oocyte donors: a randomized clinical trial.

BACKGROUND: Little information is available on the outcome of controlled ovarian hyperstimulation (COH) using GnRH antagonist in oocyte donation cycles especially in comparison with the short GnRH agonist protocol. This study was aimed at comparing the two stimulation protocols in oocyte donation (OD) cycles. METHODS: A total of 113 donors randomly received COH using either GnRH antagonist or GnRH agonist. The primary endpoint was the mean number of mature oocytes retrieved per started donor cycle. Secondary endpoints were the mean number of cumulus-oocyte-complexes (COCs) retrieved, the mean proportion of mature oocytes, pregnancy and implantation rates in recipients. RESULTS: Oocytes were distributed to 166 recipients. The mean number (+/- SD) of COC (11.6 +/- 5.8 versus 12.1 +/- 6.7), mature oocytes (8.4 +/- 4.4 versus 8.9 +/- 5.3) and the proportion of mature oocytes (70.8 versus 75.7%) retrieved per started donor cycle were similar in the antagonist and agonist groups, respectively. The implantation rate (26.1 versus 30.1%), clinical (40.2 versus 45.6%) and ongoing pregnancy rate per recipient cycle (32.2 versus 37.9%) were comparable in antagonist and agonist protocols, respectively. CONCLUSIONS: Similar mean number of mature oocytes and comparable pregnancy rates are achieved after OD in which donors received COH using GnRH antagonist or short GnRH agonist protocols.

Adult↗

PubMed1995

Evaluation of the impact of concurrent gonadotropin-releasing hormone (GnRH) antagonist administration on GnRH agonist-induced gonadotrope desensitization.

OBJECTIVE: To evaluate the impact of chronic GnRH antagonist therapy on the extent of GnRH agonist-induced gonadotrope desensitization. DESIGN: Prospective and controlled. SETTING: Primate Research Center. PARTICIPANTS: Six reproductive age cycling female baboons (Papio cyanocephalus anubis). INTERVENTIONS: The animals were divided into two groups. Group A received a total of 19 pulses of 0.83 microgram/kg leuprolide acetate (LA) on a 12-hour dosing schedule. Group B received Nal-Lys (3 mg/kg then 1 mg/kg every other day) for 1 week and then added an identical 19 pulses of LA while continuing Nal-Lys therapy. MAIN OUTCOME MEASURES: Characterization of the gonadotropin response was done by collecting serum samples at -15, 0, 15, 30, 60, 90, 120, 240, and 480 minutes relative to the injection of the LA. RESULTS: After equivalent baseline responses, the baboons pretreated with Na-Lys had an increased LH and FSH response to the administration of the LA. After a total of 19 pulses of the LA, the Nal-Lys-treated animals had an increased FSH response in comparison to the untreated controls. This indicates that the extent of gonadotrope desensitization was reduced in the presence of the GnRH antagonist. CONCLUSIONS: The presence of GnRH antagonist reduces the extent of gonadotrope desensitization in response to the administration of repetitive pulses of GnRH agonist.

Animals↗

PubMed1990

A novel regimen of gonadotropin-releasing hormone (GnRH) antagonist plus pulsatile GnRH: controlled restoration of gonadotropin secretion and ovulation induction.

Using a primate model, we have tested a novel regimen of gonadotropin-releasing hormone (GnRH) antagonist plus pulsatile GnRH for the achievement of controlled restoration of gonadotropin secretion and ovulation induction. As a prelude, ovariectomized cynomolgus monkeys (n = 3) were treated with Antide ([N-Ac-D-Nal(2)1, D-pCl-Phe2, D-Pal(3)3, Lys(Nic)5, D-Lys(Nic)6, Lys(iPr)8, D-Ala10]-GnRH) (3 mg/kg per day) for 6 consecutive days. On the 7th day, pulsatile GnRH therapy was initiated in a 7 day-on: 7 day-off regimen for a total of four exposures. Next, four intact monkeys were given Antide to suppress ovarian function (estradiol less than 10 pg/mL) followed by pulsatile GnRH. In the ovariectomized monkeys, Antide-induced suppression of gonadotropin concentrations was reversed by the pulsatile GnRH so that follicle-stimulating hormone concentrations were completely normalized and luteinizing hormone concentrations were returned to within the lower range (+/- 2 SD) of the pretreatment mean. The abruptness of the onset or loss of gonadotropin secretion was precisely synchronized with the weekly on and off phases of the GnRH pulse regimen. In intact monkeys, ovarian steroid secretions were abruptly subdued and then successfully re-established by pulsatile GnRH in the face of sustained circulating levels of Antide. Thus, we conclude that our primate model of combination therapy, GnRH antagonist plus pulsatile GnRH, establishes the possibility of a new clinical treatment regimen for patients desiring relief from the sequelae of hyperandrogenemia (polycystic ovarian disease) and ovulatory dysfunction.

Animals↗

PubMed1993

Hormonal responses to the new potent GnRH antagonist Cetrorelix.

GnRH antagonists, unlike the GnRH agonists, immediately suppress gonadotropins and testosterone secretion without initial stimulatory effect. We report here on a single-dose study with the new GnRH antagonist Cetrorelix (Ac-D-Nal(2)1, D-Phe(4C1)2, D-Pal3, D-Cit6, D-Alal0) in 25 normal men. The study involved five different dose groups (0.25, 0.5, 1.0, 1.5 or 3.0 mg) and subjects were observed over a 40 h period. Five men served as controls. Serum levels of LH, FSH and testosterone decreased rapidly with a dose-related decline for testosterone of 25%, 24%, 41%, 53% and 72%, respectively, for testosterone within the first 8 h of antagonist administration. All effects were reversible and no serious side effects were observed. Thus, this GnRH antagonist is active in men even in small doses and could become a new therapeutic tool for sex hormone-dependent diseases. Cetrorelix seems to have the highest suppressive rate per mg peptide of all other antagonists from the literature, such as Nal-Glu (Ac-D-Nal(2)1, D-Phe(4Cl)2, D-Pal3, Arg5, D-Glu6(AA), D-Alal0), Detirelix (Ac-D-Nal(2)1, D-pCl-Phe2, D-Trp3, D-hArg(Et2)6, D-Alal0) or 4F (Ac-delta 3Prol, 4F-D-Phe2, D-Trp3,6). During the time of suppression after a dose of 3 mg there was an LH and testosterone peak in the early morning coinciding with the testosterone peak in untreated men. The GnRH antagonist seems to unmask the circadian rhythm of LH secretion.

Adult↗

PubMed2004

GnRH antagonist versus long GnRH agonist protocol in poor responders undergoing IVF: a randomized controlled trial.

BACKGROUND: This is the first published report of a prospective, randomized, controlled trial comparing a fixed, multi-dose GnRH antagonist protocol with a long GnRH agonist protocol in poor responders undergoing IVF. METHODS: Sixty-six poor responders were randomized into two groups: the study group received 0.25 mg of cetrorelix daily starting on day 6 of stimulation; the control group received 600 microg of buserelin acetate daily starting in the mid-luteal phase of the preceding cycle. Both groups were given a fixed dose of recombinant FSH (300 IU daily) for stimulation. RESULTS: There were no significant differences in the cycle cancellation rates, duration of stimulation, consumption of gonadotrophins, and mean numbers of mature follicles, oocytes and embryos obtained. The implantation rates were similar, but the number of embryos transferred was significantly higher for the antagonist group (2.32 +/- 0.58 versus 1.50 +/- 0.83; P = 0.01). The pregnancy rates were also higher in the antagonist group, but the difference was not statistically significant. CONCLUSION: A fixed multi-dose GnRH antagonist protocol is feasible for patients who are poor responders on a long agonist protocol; however, our study failed to demonstrate an overall improvement in ovarian responsiveness. Clinical outcomes may be improved by developing more flexible antagonist regimens, an approach that requires further evaluation.

Adult↗

PubMed1987

Gonadotropin-releasing hormone (GnRH)-binding sites in human breast cancer cell lines and inhibitory effects of GnRH antagonists.

GnRH-binding sites have previously been described in human breast tumors, and a GnRH agonist has been shown to inhibit growth of the MCF-7 human breast cancer cell line. We have investigated the presence of GnRH-binding sites in ZR-75-1, MDA-MB-231, Sk Br 3, MDA-MB-157, and MCF-7 human breast cancer cell lines and the effect of GnRH analogs on the incorporation of [3H]thymidine and 14C-labeled amino acids into DNA and protein. Specific GnRH-binding sites were present in membrane preparations of all five human breast carcinoma cell lines. Studies in three cell lines indicated low affinity (Kd, 1.6-3.0 X 10(-6) M) GnRH binding similar to that reported in human placenta and corpus luteum. In contrast, human pituitary GnRH receptors were of high affinity (Kd, 4.8 X 10(-9) M). Breast carcinoma cell GnRH-binding sites also differed from the pituitary receptor in their inability to discriminate between GnRH and superactive analogs. Binding of a [125I]GnRH analog to ZR-75-1 breast cancer cells and pituitary membranes was affected similarly by various cations. GnRH antagonists rapidly inhibited [3H]thymidine incorporation into DNA (within 3 hr), and this effect was reversible. GnRH antagonists also inhibited cell growth, but only after 6 days. GnRH agonists did not alter either thymidine incorporation or growth. The present observations of low affinity GnRH-binding sites in breast cancer cell lines and inhibitory effects of GnRH antagonists point to the possibility of an autocrine regulatory role of GnRH-like peptides in mammary cells.

Breast Neoplasms↗