Women with declining ovarian reserve may demonstrate a decrease in day 3 serum inhibin B before a rise in day 3 follicle-stimulating hormone.

OBJECTIVE: To test the hypothesis that women with declining ovarian reserve may demonstrate a decrease in day 3 serum inhibin B levels before a rise in day 3 serum FSH levels. DESIGN: Case-control study. SETTING: Tertiary care fertility center. PATIENT(S): One hundred nine women with nonovarian infertility (tubal factor or male factor) and 47 women with declining ovarian reserve who underwent assisted reproductive techniques. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Serum inhibin B and FSH levels, number of ampules of gonadotropins administered, E2 levels on the day of hCG administration, number of oocytes retrieved, clinical pregnancy rate, and cycle cancellation rate. RESULT(S): Women who had declining ovarian reserve as demonstrated by an increased gonadotropin requirement, a decreased E2 response, fewer retrieved oocytes, a lower clinical pregnancy rate, and a higher cycle cancellation rate had lower day 3 serum inhibin B levels despite having nonelevated day 3 FSH levels similar to those of women with nonovarian infertility. CONCLUSION(S): Women with declining ovarian responsiveness and clinical outcomes consistent with declining ovarian reserve had decreased day 3 serum inhibin B levels despite having nonelevated day 3 serum FSH concentrations. Declining ovarian reserve may be demonstrated by a decrease in day 3 inhibin B levels before a rise in day 3 FSH levels.

Elevated level of follicular fluid vascular endothelial growth factor is a marker of diminished pregnancy potential.

OBJECTIVE: To evaluate whether differences in follicular fluid vascular endothelial growth factor (FF VEGF) concentrations are observed between women achieving a clinical pregnancy and those failing to conceive. DESIGN: Retrospective chart review and analysis of FF VEGF concentrations. SETTING: University teaching center. PATIENT(S): Fifty-seven women < or =42 years of age undergoing follicular aspiration in preparation for IVF or GIFT. INTERVENTION(S): Analysis of FF VEGF concentrations and chart review of a single IVF or GIFT cycle. MAIN OUTCOME MEASURE(S): Follicular fluid VEGF concentrations, clinical pregnancy rate, age, ampules of gonadotropins used, oocytes retrieved, peak estradiol serum concentrations, day 3 FSH levels, and fertilization rate. RESULT(S): Women who did not conceive had higher FF VEGF concentrations than women achieving a clinical pregnancy (4.409 + 2,387 versus 2.793 +/- 1,180 pg/mL: P < .001). A negative correlation was observed between FF VEGF concentrations and peak estradiol levels and number of oocytes retrieved. A positive correlation was found for FF VEGF and patient's age and ampules of gonadotropins used. CONCLUSION(S): Elevated FF VEGF concentrations are associated with poor conception rates after IVF or GIFT.

Dimeric inhibin: a direct marker of ovarian aging.

OBJECTIVE: To investigate whether luteal secretion of inhibin-a is altered in the perimenopausal transition and to evaluate whether luteal inhibin secretion is correlated with other markers of ovarian reserve such as FSH and inhibin-b. DESIGN: Prospective study. SETTING: Reproductive Endocrinology Laboratories at The Ohio State University. PATIENT(S): Twenty-five women 39-52 years of age with regular menstrual cycles. INTERVENTION(S): Daily urine samples were monitored (LH predictor kit) to identify the day of ovulation. Blood samples obtained on days 6 and 8 after the LH surge and on day 3 of the subsequent follicular phase were assayed for FSH, E2, progesterone. inhibin-a, and inhibin-b. MAIN OUTCOME MEASURE(S): Serum levels of inhibin-a, inhibin-b, FSH, E2, and progesterone. RESULT(S): Luteal phase inhibin-a and follicular phase inhibin-b were correlated inversely with age in perimenopausal women. In addition, luteal phase inhibin-a and follicular phase inhibin-b levels were correlated inversely with follicular phase FSH levels. CONCLUSION(S): Both luteal phase inhibin-a and follicular phase inhibin-b levels are correlated inversely with age during the fifth decade of life. These findings suggest that corpus luteum function is altered during the perimenopausal transition. Moreover, these direct measures of ovarian function may be more sensitive indicators of "ovarian reserve" than indirect indicators such as pituitary FSH secretion.

Inhibin-B: the physiologic basis of the clomiphene citrate challenge test for ovarian reserve screening.

OBJECTIVE: To determine inhibin-B concentrations during ovarian reserve screening in women with normal and diminished ovarian reserve as determined by the clomiphene citrate challenge test. DESIGN: Retrospective. SETTING: Tertiary fertility center. PATIENT(S): Women undergoing ovarian reserve screening for a routine fertility evaluation. INTERVENTION(S): Clomiphene citrate challenge test. MAIN OUTCOME MEASURE(S): Inhibin-B concentrations on menstrual days 3 and 10. RESULT(S): Nineteen patients with normal ovarian reserve and 15 with diminished ovarian reserve had serum inhibin-B concentrations determined during ovarian reserve screening. For all patients, day 10 inhibin-B concentrations were higher than day 3. Women with normal ovarian reserve had higher inhibin-B concentrations on both days 3 and 10 than women with diminished ovarian reserve. Inhibin-B concentrations demonstrated a negative correlation with FSH levels on both cycle days 3 and 10 and a positive correlation with E2 on cycle day 10. CONCLUSION(S): Women with diminished ovarian reserve during ovarian reserve screening had reduced granulosa cell inhibin-B production compared with women with normal ovarian reserve. The lower inhibin-B concentrations may be responsible for the elevated FSH concentrations and may be indicative of the aging follicular apparatus.

Follicular fluid vascular endothelial growth factor concentrations are elevated in women of advanced reproductive age undergoing ovulation induction.

OBJECTIVE(S): To determine whether follicular fluid (FF) from women of advanced reproductive age had a relative deficiency of the angiogenic cytokine vascular endothelial growth factor/vascular permeability factor. Furthermore, we sought to determine whether luteinized granulosa cells secrete vascular endothelial growth factor/vascular permeability factor in response to hypoxia. DESIGN: Retrospective cohort study. SETTING: University teaching hospital. PATIENTS: Women undergoing follicular aspiration after superovulation in preparation for IVF-ET. Women of advanced reproductive age consisted of 21 women > or = 38 years old (range, 38 to 46 years); 15 subjects < or = 30 years served as the control population. INTERVENTION(S): Granulosa cells and FF were collected by transvaginal aspiration 35 hours after hCG. Granulosa cells from two women were cultured for 24 and 48 hours in M199 + 10% fetal bovine serum in 1% O2-5% CO2-94% N2 (hypoxic) or 95% air-5% CO2 (normoxic) without or with 0.1 mol/L cobalt chloride. MAIN OUTCOME MEASURE(S): Pooled FF vascular endothelial growth factor/vascular permeability factor concentrations and media vascular endothelial growth factor/vascular permeability factor accumulation at 24 and 48 hours were determined. RESULT(S): Follicular fluid vascular endothelial growth factor/vascular permeability factor concentrations were higher in advanced reproductive age women compared with younger women (3,735 +/- 2,155 versus 2,205 +/- 952 pg/mL, mean +/- SD). Accumulation of vascular endothelial growth factor/vascular permeability factor at 24 and 48 hours was 391 +/- 54 and 744 +/- 2 pg/mL in media maintained in 5% CO2 and air. Cobalt chloride induced a marked increase in vascular endothelial growth factor/vascular permeability factor (2,008 +/- 52 pg/mL at 24 hours and 3,630 +/- 519 pg/mL at 48 hours). An intermediate but significant increase in vascular endothelial growth factor/vascular permeability factor (733 +/- 35 pg/mL at 24 hours and 2,675 +/- 864 pg/mL at 48 hours) was observed with 1% O2 compared with normoxic controls. CONCLUSION(S): After hMG and hCG administration the FF from women of advanced reproductive age showed increased vascular endothelial growth factor/vascular permeability factor concentrations compared with younger women. Increased vascular endothelial growth factor/vascular permeability factor concentrations could be consistent with a hypoxic environment within follicles of older women.

Interleukin-1 beta modulates prostaglandin and progesterone production by primate luteal cells in vitro.

Increasing evidence suggests that cytokine products of the immune system may play a regulatory role in corpus luteum regulation in several species. The role of cytokines in primate luteal function, however, remains unclear. In the present study we examined the effects of interleukin-1 beta (IL-1 beta), tumor necrosis factor alpha (TNF alpha), and interferon-gamma (IFN-gamma) on progesterone and prostaglandin (PGE2, PGF2 alpha) production by primate luteal cells in vitro. Specifically, corpora lutea were removed from normally cycling cynomolgus monkeys (n = 30 corpora lutea) during either the early (Days 3-5 after the estimated LH surge), mid (Days 8-10), or late (Days 12-14) luteal phase of the menstrual cycle. The corpora lutea were dispersed into individual cells using collagenase, DNase, and hyaluronidase. Approximately 50,000 viable luteal cells per tube were incubated in Ham's F-10 medium with increasing concentrations of IL-1 beta (0.1-10 ng/ml), TNF alpha (1-100 ng/ml), or IFN-gamma (10-1000 U/ml) in the presence and absence of hCG for 8 h at 37 degrees C. TNF alpha and IFN-gamma had no effect on progesterone PGE2, or PGF2 alpha production during any phase of the cycle at the doses tested. In contrast, IL-1 beta significantly stimulated PGF2 alpha production in a dose-dependent manner during the mid and late luteal phases (p < 0.05). Human CG alone had no effect on PGE2 or PGF2 alpha production by dispersed luteal cells in vitro but inhibited IL-1 beta-stimulated PGF2 alpha production. As expected, hCG stimulated progesterone production by primate luteal cells in vitro. Interestingly, IL-1 beta inhibited this hCG stimulation of progesterone production. In summary, these date suggest that IL-1 beta is a potentially important modulator of prostaglandin production by the primate corpus luteum. In view of this, cytokine-mediated changes in prostaglandin production by the primate corpus luteum may participate in the physiological regulation of luteal function.

Identification of gonadotrophin surge-inhibiting factor (GnSIF)/attenuin in human follicular fluid.

Evidence from several laboratories suggests that the ovaries of many species produce a non-steroidal factor called gonadotrophin surge-inhibiting or attenuating factor (GnSIF) which may regulate the response of the pituitary to gonadotrophin-releasing hormone (GnRH) and as such, may modulate the timing and/or amplitude of the luteinizing hormone (LH) surge. We have recently isolated a candidate GnSIF from porcine follicular fluid (PFF). Porcine GnSiF is a 69 kDa protein which has undetectable inhibin and follistatin immunological and biological activity. The present study was designed to purify and identify GnSIF from human follicular fluid. GnSIF activity was measured as suppression of GnRH-stimulated LH secretion from rat pituitary cells in primary culture. Human follicular fluid (approximately 500 ml) was recovered from patients undergoing in-vitro fertilization (IVF). GnSIF was purified by heparin-sepharose, Q-sepharose, S-sepharose, and hydrophobic interaction chromatography followed by isoelectric focusing. Gel electrophoresis and Western blot were used to identify human GnSIF and compare it with porcine GnSIF. Using these steps, we obtained a highly-purified preparation of GnSIF that manifests in-vitro bioactivity and chromatography characteristics similar to those observed for porcine GnSIF and that hybridizes with a porcine GnSIF antibody. Following treatment with human chorionic gonadotrophin/human menopausal gonadotrophin (HMG/HCG), human follicular fluid contained roughly 25% of the GnSIF (per mg protein) present in porcine follicular fluid. We conclude that GnSIF is present in human follicular fluid and may participate in the regulation of gonadotrophin secretion in this species.

Purification of a candidate gonadotropin surge inhibiting factor from porcine follicular fluid.

Several lines of evidence suggest that the ovaries of many species produce a nonsteroidal substance, termed gonadotropin surge inhibiting factor (GnSIF), which inhibits the midcycle gonadotropin surge and attenuates the pituitary response to endogenous or exogenous GnRH. We have previously reported the partial purification of GnSIF from porcine follicular fluid (pFF) and its differentiation from inhibin. We present now the purification of GnSIF to homogeneity and determination of the partial NH2-terminal amino acid sequence. The bioassay for GnSIF used rat pituitary cells in short-term culture that were incubated with test fractions for 48 h, washed, and then incubated with 10 nM GnRH plus test fractions for 4 h. GnSIF activity is defined as the suppression of GnRH-stimulated LH secretion. GnSIF was purified from 500 ml of pFF using sequential heparin-Sepharose, anion-exchange, and cation-exchange liquid chromatography followed by gel permeation, hydrophobic interaction, and mono-Q HPLC steps. Using these six purification steps, we have obtained an apparently homogenous preparation that stains as a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. GnSIF has an apparent mol wt of 69K. Limited NH2-terminal sequence analysis reveals that GnSIF has no sequence homology with other reproductive hormones including the inhibins, activins, and follistatins. Over the dose range tested, GnSIF had no effect on basal LH or FSH secretion by pituitary cells in culture and only slightly inhibited GnRH-stimulated FSH secretion at the highest dose tested. In addition, there was no inhibin or follistatin immunoactivity in the GnSIF preparation. As such, GnSIF appears to be a novel protein in pFF that inhibits GnRH-stimulated LH secretion, and which may participate along with other ovarian proteins and steroids in the regulation of pituitary gonadotropin secretion.

Ovarian control of follicle development.

A variety of ovarian autocrine and paracrine factors may modulate folliculogenesis and steroid production. The developmental program that leads to the production of a dominant follicle involves a precise quantitative and temporal pattern of expression of a large number of genes. Follicle-stimulating hormone plays an essential role in this process, and no other ligand by itself can serve in this regulatory capacity. It is clear that a variety of growth factors can modulate follicle-stimulating hormone action by autocrine and paracrine mechanisms. Advances in the understanding of the role of growth factors, particularly the family of insulin-like growth factor-related proteins, in regulating follicle-stimulating hormone action are discussed. It is likely that complex interactions exist between follicle-stimulating hormone and the growth factors. Significantly, growth factor regulation by pituitary gonadotropins is probably a central feature of their expression. With increased understanding of the ovarian control of follicle development, it is hoped that newer and more effective regimens for synchronous follicular and oocyte maturation can be realized.

Endocrine and paracrine control of oocyte development.

The effects of gonadotropins on oocyte development are mediated through a variety of mechanisms, including production by granulosa cells of growth factors, cytokines, inhibins, activins, and steroids. Specific receptors for steroids, growth factors, and cytokines have been demonstrated on oocytes of several species. Gonadotropin modulation of follicular concentrations of these paracrine factors may ultimately be responsible for the precise regulation of oocyte function. As gonadotropin-releasing hormone antagonists and recombinant gonadotropins become available, the clinical use of more precise control of the endocrine, paracrine, and autocrine regulation of follicle growth and oocyte development can be more thoroughly investigated.

In vivo effects of a potent GnRH antagonist ORG 30850: physiologic evidence that down-regulation of GnRH receptors does not occur.

OBJECTIVE: Our purpose was to determine the pituitary responsiveness to exogenous GnRH in GnRH antagonist-suppressed ovariectomized monkeys. METHODS: This was a prospective experimental non-human primate study performed at the research laboratories of The Jones Institute for Reproductive Medicine. Seventeen long-term ovariectomized cynomolgus monkeys were studied. INTERVENTIONS: The GnRH antagonist ORG 30850 was administered to long-term ovariectomized monkeys assigned to one of six groups: single subcutaneous injections in group A (n = 4), 0.3 mg/kg; group B (n = 4), 1.0 mg/kg; and group C (n = 3), 3.0 mg/kg; and six consecutive daily subcutaneous injections in group D (n = 2), 0.3 mg/kg; group E (n = 2), 1.0 mg/kg; and group F (n = 2), 3.0 mg/kg. Blood samples were collected daily from 10 days before treatment until 22 days after treatment, then weekly for 6 additional weeks. Intravenous GnRH stimulation tests (10 micrograms/kg) were performed on the day after vehicle injection (control) and the day after completion of treatment(s), and then at weekly intervals. The main outcome measures were serum levels of LH, FSH, and ORG 30850. RESULTS: Administration of ORG 30850 resulted in suppression (P < .05) of LH and FSH in all treatment groups. Long-term suppression (greater than 2 weeks) was evident in all primates receiving a cumulative dose of at least 1 mg/kg. Paradoxically, the responsiveness of the pituitary to exogenous GnRH was accentuated during the time of maximal tonic LH/FSH suppression. CONCLUSIONS: ORG 30850 is a potent long-acting GnRH antagonist. Furthermore, the present in vivo demonstration of heightened pituitary responsiveness to exogenous GnRH emphasizes the divergent mechanisms of action of GnRH antagonists and GnRH agonists.

Recombinant human follicle-stimulating hormone stimulates multiple follicular growth, but minimal estrogen production in gonadotropin-releasing hormone antagonist-treated monkeys: examining the role of luteinizing hormone in follicular development and steroidogenesis.

The two-cell theory predicts that follicular steroidogenesis requires the coordinate actions of both FSH and LH; however, the role of LH in follicular growth is less clear. The present study was designed to investigate the relative importance of LH and FSH in follicular growth and steroidogenesis. Cynomolgus monkeys were treated with a GnRH antagonist (antide; 3 mg/kg.day) for 20 days beginning in the midluteal phase of the menstrual cycle. After 10 days of antide administration, monkeys were injected with recombinant human FSH (rhFSH; 10 IU; n = 3), human menopausal gonadotropin (hMG; 10 IU; n = 3), or FSH plus 0.5 IU LH (n = 3) twice daily for 10 days. rhFSH stimulated multiple follicular development; however, peak serum estradiol levels were only 943 +/- 195 pmol/L. In contrast, monkeys treated with the same dose of hMG had significantly higher (P < 0.05) peak estradiol levels (6013 +/- 1322 pmol/L). The addition of 0.5 IU LH to the rhFSH treatment resulted in serum estradiol levels similar to those in monkeys treated with rhFSH only. Importantly, no differences in follicle number or size were evident among these treatment groups. Follicular fluid estradiol levels were consistent with serum levels (rhFSH, 187 +/- 11 nmol/L; hMG, 1531 +/- 173 nmol/L). Even larger proportional differences in follicular fluid androstenedione (rhFSH 13.6 +/- 1.4 nmol/L; hMG, 307 +/- 97.7 nmol/L) levels were found. The results in this LH-deficient primate model suggest that FSH alone is capable of stimulating ovarian follicular growth; however, the resulting follicles manifest minimal estradiol production, probably due to deficiencies in the LH-induced precursors to estradiol.

Non-competitive anti-oestrogenic activity of progesterone antagonists in primate models.

We have summarized some of the studies containing basic biological data suggesting potential therapeutic utility of the anti-proliferative activity of antiprogestins on uterine tissues. The non-competitive anti-oestrogenic effects of RU486 were examined using oestradiol-treated ovariectomized monkeys given RU486, progesterone or both. The oestradiol-induced luteinizing hormone surge of control animals was abrogated by progesterone and/or RU486. Secretory transformation by progesterone was inhibited by RU486 co-administration. RU486 alone (1 mg/kg) induced endometrial secretory transformation, but higher doses (5 mg/kg) induced inhibited proliferation and secretory activity. Thus, in the presence of progesterone, RU486 is antagonistic but, in its absence, RU486 exhibits endometrial progestational effects at low doses and an anti-proliferative (anti-oestrogenic) effect at higher doses. These data encourage continued evaluation of RU486 as a potential contraceptive agent acting at the pituitary and/or endometrial level. Our study also demonstrates that after physiological oestradiol replacement therapy, oestradiol receptor concentrations rise dramatically following antiprogestin treatment; this effect was dose-dependent.

Early follicle growth in the juvenile macaca monkey ovary: the effects of estrogen priming and follicle-stimulating hormone.

The mechanism(s) that drives preantral and early antral follicle growth in the primate ovary is poorly understood. We previously reported that estrogen does not stimulate preantral or early antral follicle growth in juvenile primates. The purpose of the present study was to determine whether estrogen priming may play a role in enhancing FSH-stimulated follicle growth. Eight juvenile monkeys received implants on Day 1 of silastic capsules containing estradiol (or vehicle) to elevate circulating estradiol levels. Daily FSH injections were initiated on Day 4 and continued for up to 12 days. The left ovary was removed on Day 8 and served as a control. Ovulation was induced, and a luteal phase followed. On the first day of menses, the estradiol (vehicle) capsule-FSH protocol was repeated. The remaining ovary was removed on Day 8 of the second cycle. The number and size of all follicles in both ovaries were evaluated by light microscopy. Results indicate that estrogen priming in the first cycle did not enhance growth of preantral or antral follicles, but did result in fewer developing follicles > 1.0 mm in diameter, this was accompanied by an increase in early atretic antral follicles of similar size. In the second cycle, an even further reduction in number and size of developing antral follicles > 1.0 mm in diameter was observed. These data suggest that pretreatment with exogenous estrogen has an anti-follicular action on follicle growth in these primates.

The identification of gonadotrophin surge inhibiting factor and its role in the regulation of pituitary gonadotrophin secretion.

Evidence from several laboratories suggests that the ovaries of rats, pigs, monkeys and women produce a non-steroidal factor which inhibits or attenuates the mid-cycle gonadotrophin surge. This substance is present in follicular fluid and we have called it gonadotrophin surge inhibiting factor (GnSIF). Utilizing a rat pituitary cell bioassay, we have monitored GnSIF activity during purification from porcine follicular fluid (PFF). Rat pituitary cells in short-term culture were incubated with GnSIF for 48 h, washed and then exposed to gonadotrophin releasing hormone (GnRH) plus GnSIF for 4 h. GnSIF activity was defined as suppression of GnRH-stimulated LH secretion over 4 h, and inhibin activity was expressed as suppression of basal follicle stimulating hormone (FSH) secretion over 48 h. Approximately 5 l of PFF was fractionated through heparin-Sepharose, Q-Sepharose, Mono-S, hydroxylapatite, and gel permeation chromatography steps. This fractionation removes all detectable inhibin and follistatin immunoactivity and bioactivity. The purified GnSIF inhibits GnRH-stimulated LH secretion with little or no effect on basal FSH release. In summary, we have obtained a purified preparation of GnSIF which contains undetectable inhibin and follistatin. As such, GnSIF appears to be distinct from other known gonadal proteins regulating reproductive function, and may participate along with the inhibins, activins and follistatins in the gonadal regulation of pituitary gonadotrophin secretion.

New trends in combined use of gonadotropin-releasing hormone antagonists with gonadotropins or pulsatile gonadotropin-releasing hormone in ovulation induction and assisted reproductive technologies.

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.

GnRH antagonists suppress prolactin release in non-human primates.

GnRH antagonists, such as Antide, are being evaluated for potential contraceptive applications. Although their contraceptive efficacy clearly results from their rapid inhibitory effects on gonadotropin release, there remains the possibility of other incidental effects. Under certain physiological conditions, the release of prolactin (Prl) appears to be temporally related to the secretion of luteinizing hormone (LH) and hence by inference to the secretion of GnRH. Here, we examined the effects of the GnRH antagonist Antide on the release of LH and Prl. Under agonadal conditions, a remarkable concordance was seen between LH and Prl pulses with up to 100% of pulses being coincident. Administration of Antide resulted in a rapid parallel decline in both LH and Prl with LH levels falling by 50% within 2 h and Prl levels falling by 30-40%. At this dose of Antide (1.0 mg/kg, sc), pulsatile release of LH and Prl continued albeit at a much reduced amplitude. The administration of a bolus of exogenous GnRH in the face of GnRHant-induced suppression resulted in prompt release of LH and Prl in all 3 monkeys. Since Antide inhibits the release of LH and Prl in a parallel fashion, and GnRH re-stimulates the release of both hormones in a parallel fashion, we conclude that the synchronous pulsatile release of LH and Prl observed in the agonadal monkey is due to a direct action of GnRH. What this action is for Prl release, and how it relates to the control of dopamine or other neuroendocrine mechanisms normally controlling the release of Prl remains unclear. It also remains to be seen whether this GnRH antagonist-induced suppression of Prl will have physiologic significance.

Antide bioavailability: single dose administration for suppression of testosterone and inhibin in male monkeys.

The pharmacokinetics and pharmacodynamics of a single sc injection of Antide on testosterone (T) and inhibin secretion in intact male cynomolgus monkeys were examined. Fifteen primates were randomized to three groups receiving: propylene glycol and water vehicle, 3 mg/kg Antide, and 10 mg/kg of Antide. Antide at the 10 mg/kg dose caused long-term suppression of T ranging from 24-56 days. At the 3 mg/kg dose, suppression of T was of shorter duration. Serum Antide levels were significantly greater in the 10 mg/kg group than the 3 mg/kg group (p less than 0.02), both initially and through 35 days post-treatment. The duration of testosterone inhibition and sustained Antide levels were significantly correlated (p less than 0.01). Inhibin concentrations followed the same general pattern as testosterone reaching a nadir on day 21 post-treatment before subsequent recovery. The prolonged suppressive effect of Antide on T without detectable side effects makes this compound an excellent candidate for clinical evaluation.

Suppression of ovarian estradiol secretion by a single injection of antide in cynomolgus monkeys during the early follicular phase: immediate, sustained, and reversible actions.

We examined the effects of the GnRH antagonist antide on ovarian estrogen secretion after a single administration in intact cycling cynomolgus monkeys (n = 5/group) during the early follicular phase. Antide treatment on menstrual cycle day 2 resulted in a dose-dependent increase in menstrual cycle lengths (mean +/- SEM) to 38 +/- 3, 49 +/- 8, and 96 +/- 15 days for 3.0, 10.0, and 30.0 mg/kg antide, respectively, in association with inhibition of folliculogenesis and suppression of estradiol concentrations to therapeutic levels. Subsequent resumption of apparently normal ovulatory menstrual cycles occurred in all 15 individuals. In addition, all four monkeys from the group treated with 30 mg/kg antide that were available for subsequent matings became pregnant and had normal babies. Thus, no irreversible consequences or adverse effects of antide on reproductive function in these primates was observed. No allergic or other adverse reactions were found locally or systemically in these primates, even at the highest dose of antide. To the extent that this primate model is a paradigm for clinical therapeutics, a single treatment of antide (30 mg/kg) provides sustained inhibition of ovarian estradiol secretion for about 2 months, thus demonstrating the feasibility of using antide for clinical management of steroid-dependent conditions.

Early folliculogenesis in primate ovaries: testing the role of estrogen.

The purpose of this study was to examine the effect of an exogenous estrogen, diethylstilbestrol (DES), on follicle development in the ovary of a juvenile primate. The immature cynomolgus monkey (12-22 mo) was used as a model since ovaries at this age lack endogenous gonadotropin support but are capable of responding to exogenous hormonal stimulation. In addition, the pituitary gland receives virtually no GnRH stimulation and under these conditions lacks responsiveness to estrogen feedback. Two groups of three monkeys each received DES for 14 days. Members of the second group also were given GnRH antagonist to assure no GnRH action upon the gonadotropes. The left ovary of each monkey was removed just prior to Day 1 of DES treatment and served as the control. The right ovary was removed on Day 14 of treatment. Both ovaries from each monkey were prepared for evaluation by light microscopy. Results indicated that both the number of preantral follicles and the mean number of medium-sized (0.5-1 mm in diameter) developing antral follicles decreased significantly (p less than 0.05) in the DES-treated ovaries with no increase in early-atretic antral follicles. These data suggest that DES, at the amount administered, inhibits the growth of both preantral and medium-sized antral follicles in the primate. Whether these effects are manifest directly at the follicle level or are mediated by other mechanisms remains to be determined.