Search PubMed⌕ Search

Biomedical subjects

M E Wierman

Publications and source records attributed to M E Wierman.

At least 37 records · Page 2Linked to original sources
PubMed1992

Phorbol ester activation of the protein kinase C pathway inhibits gonadotropin-releasing hormone gene expression.

The effects of the phorbol ester 12-O-tetradecanoyl phorbol 13-acetate (TPA), an activator of protein kinase C (PKC), and the PKC inhibitor staurosporine on GnRH secretion and mRNA levels were studied in GT1-7 hypothalamic neuronal cells. Dose-response and time-course studies revealed that TPA (10(-8) M) acutely increased GnRH secretion 3-fold at 3-6 h, which then declined to baseline at 24 h, while it progressively decreased GnRH mRNA levels by 50% and 70% at 6 and 24 h, respectively. To ensure that these effects were due to activation and not down-regulation of PKC, cells were treated for 30 min with TPA (10(-8) M). This brief exposure to TPA also resulted in a decrease (60%) in GnRH mRNA levels at 6 h, with a 1.5- to 2-fold increase in GnRH secretion compared to control values, suggesting that activation of PKC decreases the pretranslational expression of GnRH while increasing GnRH secretion. Additional studies measured PKC activity and documented a shift from a cytosolic to a membrane fraction after incubation with TPA, again supporting PKC activation. Exposure of GT1-7 cells to staurosporine (10(-8) M), a PKC inhibitor, resulted in no change in the level of GnRH mRNA or secretion at 6 h. However, incubation with both TPA and staurosporine prevented the decrease in GnRH mRNA levels and partially blocked the increase in GnRH secretion induced by TPA. We conclude that TPA, by activating the PKC pathway, acutely increases GnRH secretion, but dramatically decreases GnRH gene expression. The exact mechanism of these divergent effects on the synthesis and secretion of GnRH remain to be elucidated.

Alkaloids↗
PubMed1992

The natural history of autonomous gonadal function, adrenarche, and central puberty in gonadotropin-independent precocious puberty.

Gonadotropin-independent precocity (GIP) is a syndrome marked by precocious pubertal development in the absence of pubertal levels of gonadotropins. To investigate the discrete patterns of central nervous system, gonadal, adrenal, and skeletal maturation in this syndrome, we conducted longitudinal studies spanning up to 10 yr in two such affected individuals. A cross-sectional analysis of adrenal androgen secretion was performed in nine additional patients to assess further the time course of adrenarche in GIP. Serial evaluations revealed progression of secondary sexual characteristics, statural growth, and skeletal maturation, all consistent with ongoing exposure to pubertal gonadal steroid levels. On the other hand, adrenarche (n = 11) and spontaneous and GnRH-stimulated gonadotropin secretion (n = 2) progressed in chronological age-appropriate manners despite long term pubertal levels of gonadal sex steroid secretion. After the development of central puberty, as documented by the appearance of pulsatile gonadotropin secretion, we sought to determine whether the potential for gonadal autonomy persisted. Despite complete pituitary desensitization induced by administration of a GnRH agonist, both patients studied demonstrated an ongoing capacity to secrete pubertal levels of gonadal steroids. Our study suggests that the timing of adrenarche and central puberty in these subjects with GIP was apparently unaltered by prolonged exposure to gonadal steroids. Subsequent to the development of central puberty, pulsatile gonadotropin secretion may override and, thus, mask the underlying defect(s) in adolescents and adults with histories of GIP.

Adrenal Glands↗
PubMed1990

Androgen selectively stimulates follicle-stimulating hormone-beta mRNA levels after gonadotropin-releasing hormone antagonist administration.

Gonadal steroids act both at the hypothalamus and pituitary to regulate gonadotropin subunit gene expression. To investigate positive feedback effects of sex steroids on gonadotropin subunit mRNA levels in vivo, independent of effects on gonadotropin-releasing hormone (GnRH), the following studies were performed. Male and female rats, 7 days following castration, received the potent Nal/Glu GnRH antagonist (GnRHA) (500 micrograms/kg/day) for 14 days to block endogenous GnRH activity. Subgroups of animals received either estradiol benzoate (E) (10 micrograms/100 g BW/day) or testosterone propionate (T) (500 micrograms/100 g BW/day) for the last 7 days to assess the effects of reintroduction of gonadal steroids during blockade of endogenous GnRH action. Intact rats and castrated animals that received vehicle served as controls. Serum follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels were determined on trunk blood, and gonadotropin subunit mRNAs were determined by blot hybridization using radiolabeled probes specific for the rat FSH beta, alpha, and LH beta subunit and mouse beta-actin genes. Autoradiographic bands were quantitated by laser densitometry and subunit mRNA levels were compared to those in intact pituitaries. In these studies, GnRHA administration inhibited the post-castration rises in all three gonadotropin mRNAs, as well as in serum FSH and LH levels. GnRHA + E or GnRHA + T resulted in similar or further suppression of alpha and LH beta mRNA levels compared to GnRHA alone. In contrast, in both sexes, GnRHA + T stimulated FSH beta mRNAs and serum FSH levels toward those of gonadectomized controls. Thus, during GnRHA inhibition of endogenous GnRH activity, androgen uniquely stimulates FSH beta mRNA levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Androgens↗
PubMed1990

Divergent regulation of gonadotropin subunit mRNA levels by androgens in the female rat.

To examine the effects of gonadal steroids on the pretranslational regulation of the gonadotropin subunits in the female, adult female rats, beginning 7 or 28 days after ovariectomy, received daily injections of testosterone propionate (T), dihydrotestosterone propionate (D), or estradiol benzoate (E) for 7 days. Intact cycling females and ovariectomized rats that received vehicle served as controls. Serum was obtained for LH and FSH levels to assess changes in gonadotropin secretion. Total RNA from individual rats was recovered and analyzed by blot hybridization with specific radiolabeled cDNA probes for the alpha, LH beta, and FSH beta subunits. Autoradiographic bands were quantitated and standardized to mRNA levels in the intact animals. Ovariectomy resulted in a rise in serum gonadotropin levels and all three gonadotropin subunit mRNA levels. Estrogen replacement resulted in suppression of alpha, LH beta, and FSH beta mRNAs whether given at 7 or 28 days after ovariectomy. In contrast, whereas androgen replacement decreased alpha and LH beta mRNAs, D or T did not consistently suppress FSH beta mRNAs. We conclude that chronic estrogen administration to the castrated female rat uniformly suppresses all three gonadotropin subunit mRNA levels. In female rats, as in male rats, chronic androgen administration fails to negatively regulate FSH beta mRNAs.

Androgens↗
PubMed1990

Castration induces time-dependent changes in the follicle-stimulating hormone beta-subunit messenger ribonucleic acid-containing gonadotrope cell population.

We have previously observed 3- to 10-fold increases in pituitary LH beta-subunit mRNA levels in the rat 28 days after castration. These changes correlate with increases in percentages and areas of cells that bear the LH beta mRNA and with the amount of label for mRNA per cell. In contrast, FSH beta mRNA levels increase 2.5- to 4-fold 7-14 days after castration, decline to near-intact levels 28 days postcastration, and rise 4.5-fold by 96 days postcastration. The purpose of this study was to determine morphological correlates of these changes in FSH beta mRNA levels. Dispersed pituitary cells from intact and castrated rats were analyzed for FSH beta and LH beta mRNAs and protein by in situ hybridization techniques and immunocytochemistry, respectively. In intact animals over 79% of pituitary cells labeled for FSH beta mRNA were small (area less than 150 microns 2). However, 7 days after castration, the average area of labeled cells increased 4-fold (80% were over 200 microns 2 in area), without a significant change in percentages of FSH beta mRNA-containing cells. The amount of mRNA per cell (as measured by area of label per cell) increased 6-fold. Fourteen days after castration, the average area of cells containing FSH beta mRNA decreased to 2 times that in intact rats (48% were greater than 200 microns 2). The percentage of labeled cells increased from 11% (intact) to 20%. Furthermore, the dual labeling studies showed that 37% of these FSH cells were monohormonal (detected by FSH beta mRNA, but not LH beta antigen) compared with 23% in intact rats. At this same time, the FSH cells exhibited a decrease in the amount of mRNA per cell. In 21- to 84-day castrates, average areas of FSH beta mRNA remained at 2-2.5 times the areas of cells from intact rats. In addition, 21 days after surgery the percentages of labeled cells and amount of FSH beta mRNA per cell declined to those in intact rats. A greater proportion was multihormonal (only 15% expressed FSH beta mRNA but not LH beta antigens). At 84 days there were 2-fold increases in the percentages of labeled cells and the density of label, which correlate with the recovery in mRNA levels assayed at 96 days. Thus, factors that contribute to the early rise in FSH beta mRNA include increases in the amount of mRNA per cell, which coincides with increased cell area.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

Isolation and characterization of the gene encoding the beta-subunit of rat follicle-stimulating hormone.

Follicle-stimulating hormone (FSH) is a pituitary glycoprotein hormone that is comprised of two dissimilar subunits, alpha and beta, encoded by separate genes. We have isolated the gene encoding the beta-subunit of rat FSH by screening a rat genomic DNA-library by filter hybridization with bovine FSH-beta cDNA. Southern blot analysis of rat genomic DNA suggests that there is a single copy of the FSH-beta gene per haploid genome in the rat. The nucleotide sequence of the rat FSH-beta gene was determined and the amino acid sequence of the subunit was deduced. The gene is composed of three exons and two introns. The predicted amino acid sequence reveals that there is a 20-amino-acid signal peptide followed by a mature protein of 110 amino acid residues. Exons I, II, and III are 36, 187, and 1221 bp, respectively. Intron 1 (640 bp) interrupts the 5'-untranslated (UT) region (61 bp) and intron 2 (approximately 1 kb) interrupts the coding region between amino acid residues +34 and +35. Comparison of the amino acid sequence to those of the human and bovine FSH-beta subunits reveals 80% similarity to both species. The "CAGY" sequence, or the Cys-Ala-Gly-Tyr quartet of amino acids encoded by exon II is present in every other glycoprotein beta-subunit sequenced thus far, is altered in rat FSH-beta, with the Ala residue replaced by Glu. Primer extension analysis demonstrated that there is a single transcriptional start site. The nucleotide sequence of the 5'-flanking region (1 kb) was determined and compared to the nucleotide sequences of corresponding regions in the bovine and human genes. This analysis revealed that there are three regions in the 5'-flanking region of the rat FSH-beta gene that display greater than 80% sequence similarity to regions in the bovine and human genes. The second of these regions also shares similarity to segments within the 5'-flanking regions of the rat alpha- and LH beta-subunit genes. The characterization of the rat FSH-beta gene will enable further study of the regulation of rat FSH using in vitro systems.

Amino Acid Sequence↗
PubMed1989

Gonadotropin-releasing hormone-dependent regulation of gonadotropin subunit messenger ribonucleic acid levels in the rat.

The Nal-Glu GnRH antagonist (GnRHA) was given to castrate male and female rats 7 days after gonadectomy to assess the impact of selective GnRH inhibition on the steady state mRNA levels of FSH beta, LH beta, and alpha-subunit and serum levels of FSH and LH. A low dose of GnRHA (125 micrograms/kg.day) given to female rats for 1, 3, or 7 days resulted in suppression of serum FSH and LH levels by 7 days to 50% and 40%, respectively, of ovariectomized control values. LH beta mRNA levels decreased in a time-dependent manner, so that by 7 days, LH beta mRNA levels were less than those in intact controls. There were significant but less dramatic declines in alpha and FSH beta mRNA levels. A higher dose of GnRHA (500 micrograms/kg.day) for 7 or 14 days administered to castrate male or female rats resulted in inhibition of serum LH and FSH to or below levels in intact controls. At this dose, all three gonadotropin subunit mRNA levels fell from castrate values toward or below those in intact controls. Thus, although low dose GnRHA administration suppressed LH beta mRNA more than FSH beta mRNA levels, high dose GnRHA treatment resulted in equal suppression of all three gonadotropin subunits. No stimulatory effects on alpha-subunit mRNA levels were observed with either dose of GnRHA. We conclude that the pretranslational control of gonadotropin subunit biosynthesis is GnRH dependent. Adequate dose and length of administration of the potent Nal-Glu GnRHA results in suppression of both the serum gonadotropins FSH and LH and the mRNAs for FSH beta, LH beta, and alpha-subunit in female and male rats.

Animals↗
PubMed1989

The effect of altered thyroid status on pituitary hormone messenger ribonucleic acid concentrations in the rat.

To study the effects of altered thyroid status on pretranslational control of pituitary hormones, adult male rats were given propylthiouracil for 6 weeks and underwent the following studies. 1) Rats were injected with T3 at 10 micrograms/100 g BW daily for 10 days. 2) Rats were given T3 injections at 0, 0.01, 0.1, 1.0, or 10 micrograms/100 g BW for 10 days. 3) Rats were killed 0, 1, 6, or 24 h after a single injection of T3 at 10 micrograms/100 g BW or after 5 or 10 days of daily T3 injections. Pituitary mRNA concentrations of TSH beta, alpha-subunit, PRL, GH, POMC, FSH beta, and LH beta were determined for individual animals. Marked increases in TSH beta and alpha-subunit mRNAs occurred after PTU treatment, and these changes were reversed by 1.0 microgram/100 g BW T3 and within 24 h of a single T3 injection of 10 micrograms/100 g BW. Further increases in the dose or time course of T3 administration led to a relatively greater suppression of TSH beta mRNA levels than alpha-subunit mRNA levels. In contrast, GH and PRL mRNA levels were low in hypothyroid animals, and both rose toward control levels with 0.1 microgram/100 g BW T3 and by 24 h after a single T3 dose. Induction of hyperthyroidism did not further increase GH mRNA levels above control, but increased PRL mRNA levels 2-fold over control. No changes were seen in FSH beta, LH beta, or POMC mRNA levels with any treatment. Thus, studies of altered thyroid status in the rat reveal dose-response and time-course variability in the pretranslational control of TSH beta, alpha-subunit, GH, and PRL by thyroid hormone.

Animals↗
PubMed1988

Selective failure of androgens to regulate follicle stimulating hormone beta messenger ribonucleic acid levels in the male rat.

FSH beta, as well as LH beta, and alpha-subunit mRNA levels were examined in the pituitary glands of male rats after sex steroid replacement at various times (7, 28, or 90 days) after orchiectomy. Testosterone propionate, dihydrotestosterone propionate, or 17 beta-estradiol benzoate (E) were administered daily for 7 days before killing, to assess the role of different gonadal steroids on gonadotropin subunit mRNA levels. Subunit mRNAs were determined by blot hybridization using rat FSH beta genomic DNA, and alpha and LH beta cDNAs. At all time points, alpha and LH beta mRNAs increased after gonadectomy and fell toward normal levels with either androgen or estrogen replacement. FSH beta mRNA levels increased variably postcastration: 4-fold at 7 days, 2-fold at 28 days, and 4- to 5-fold at 90 days. Although E replacement uniformly suppressed FSH beta mRNAs, neither testosterone propionate nor dihydrotestosterone propionate administration suppressed FSH beta mRNA levels at any time point after orchiectomy. These data demonstrate that there is a relative lack of negative regulation of FSH beta mRNA levels by androgens in a paradigm in which E administration results in marked negative regulation of FSH beta mRNA levels. Thus, in the male rat, estrogens negatively regulate all three gonadotropin subunit mRNA levels while androgens negative regulate LH beta and alpha-subunit but fail to suppress FSH beta mRNAs.

Androgens↗
PubMed1987

Sex steroid hormone regulation of follicle-stimulating hormone subunit messenger ribonucleic acid (mRNA) levels in the rat.

Follicle-stimulating hormone (FSH) beta, luteinizing hormone (LH) beta, and alpha subunit messenger RNA (mRNA) levels were examined in rats after castration and sex-steroid replacement. Subunit mRNAs were determined by blot hybridization using rat FSH beta genomic DNA, and alpha and LH beta complementary DNA (cDNA). Rat FSH beta mRNA is 1.7 kilobase in size. After ovariectomy, female FSH beta mRNA levels increased fourfold, whereas those of LH beta and alpha increased twenty- and eightfold, respectively. With estradiol, all subunits returned toward normal levels. Male LH beta and alpha mRNA levels rose eight- and fourfold, respectively, 40 d postcastration, but FSH beta mRNA levels increased minimally. After 7 d of testosterone propionate, LH beta and alpha mRNAs declined to normal levels, whereas FSH beta mRNA increased slightly. We conclude that in female rats FSH beta is negatively regulated by gonadal steroids, but to a lesser extent than LH beta or alpha mRNAs, and there is a differential regulation of FSH beta mRNA levels in males as compared with females at the time points examined.

Animals↗
PubMed1987

Detection of luteinizing hormone beta messenger ribonucleic acid (RNA) in individual gonadotropes after castration: use of a new in situ hybridization method with a photobiotinylated complementary RNA probe.

Patterns of gonadotropin storage in individual gonadotropes change with alterations in the physiological state. After castration in the male rat, there is a 2.5-fold increase in the percentage of gonadotropes and an increase in the proportion of gonadotropes storing both LH and FSH. In addition, there are 6- to 8-fold increases in the pituitary concentrations of LH beta subunit mRNAs. In order to determine whether these changes are due to increases in the number of gonadotropes containing subunit mRNA, or the amount of mRNA per cell or both, an in situ hybridization technique using a photobiotinylated rat LH beta cRNA probe (bio-LH beta-cRNA) was applied to detect LH beta mRNA in fixed whole rat pituitary cells from intact or castrated rats. After hybridization, the bio-LH beta-cRNA was localized with either avidin-biotin peroxidase complex or the fluorescent streptavidin phycoprobe methods. The cells containing LH beta mRNA were then counted and the amount of mRNA per cell was measured by video microdensitometry. Ten percent of the anterior pituitary cells from intact animals contained LH beta mRNA. After castration (2-4 weeks) this percentage rose to 19-24.5%. Image and microdensitometric analyses showed that castration produced a 1.9-fold increase in the amount of LH beta mRNA per cell, and a 2.2-fold increase in the area of cells containing LH beta mRNA. Hence, castration resulted in an increase in the level of LH beta mRNA per cell as well as the number of LH beta mRNA-containing cells. When in situ hybridization was followed by immunocytochemistry in cells from intact rats, 83% of gonadotropes that stained for LH beta and 80% of gonadotropes that stained for FSH beta contained LH beta mRNA whereas after castration 99% of LH-storing and 93% of FSH-storing cells contained LH beta mRNA. This new in situ hybridization protocol is rapid and allows quantification of mRNA within individual gonadotropes. In addition, since the hybridization protocol does not apparently alter the gonadotropin antigens, the hormone content of the same gonadotrope may be defined by immunocytochemistry.

Affinity Labels↗
PubMed1986

Sonographic monitoring of LHRH analogue therapy in idiopathic precocious puberty in young girls.

Precocious puberty in young girls is defined as the development of secondary sexual characteristics and gonadal growth before 8 years of age. Approximately 60% of isosexual precocious development in girls has no organic cause and is termed idiopathic precocious puberty. Thirteen young girls with idiopathic precocious puberty were treated with LHRH analogue under a well-established protocol. Pelvic ultrasound was added to the protocol to examine ultrasound's role in supplying a morphologic parameter of suppression of the pubertal process. Initially, 11 patients had ovarian volumes greater than normal, and ovarian cysts measuring 0.5 cm to 4 cm in diameter were identified in seven patients. All 13 patients had enlarged pretreatment uteri greater than 3 cm in length. Eleven of these patients had a pubertal or adult uterine configuration. After 1 year of therapy, 11 patients had normal prepubertal ovarian volumes, and 12 of 13 patients had a decrease in ovarian volume. No demonstrable cysts were present at 1 year. Eleven had a reduction in uterine length. Nine of the 11 patients with a pubertal uterine configuration reverted to a more prepubertal-like morphology. The sonographic morphologic changes correlated well with laboratory and clinical data indicating suppression of the hypothalamic-pituitary-gonadal axis.

Child↗
PubMed1986

Adrenarche and skeletal maturation during luteinizing hormone releasing hormone analogue suppression of gonadarche.

During puberty the effects of adrenal androgens upon skeletal maturation are obscured by the influence of gonadal steroids. Suppression of gonadarche with an analogue of luteinizing hormone releasing hormone (LHRHa) affords an opportunity to examine the onset and progression of adrenarche in the absence of pubertal levels of gonadal steroids in a controlled fashion and to explore the relationship between adrenal androgens and the rate of epiphyseal maturation. In 29 children with central precocious puberty, gonadarche was suppressed with LHRHa administration for 1-4 yr. During LHRHa exposure, dehydroepiandrosterone sulfate (DHAS) levels, as an index of adrenal maturation, were constant or increased in an age-expected manner. The change in bone age for change in chronologic age decreased from 1.7 +/- 0.1 to 0.49 +/- 0.05 (P = 0.00005), indicating that the LHRHa-induced return to a prepubertal gonadal steroid environment was associated with a slowing of skeletal maturation. DHAS levels were correlated with the rate of skeletal advancement before (r = 0.57, P = 0.001) and during 12 to 48 mo of exposure to LHRHa (r = 0.52, P = 0.003). A negative correlation of DHAS values with subsequent increases in predicted mature height was observed (r = -0.49, P = 0.007). Thus, in children with central precocious puberty, adrenarche progressed normally during LHRHa suppression of gonadarche. In children with the onset of progression of adrenarche during maintenance of a prepubertal gonadal steroid milieu, there was less evidence than in preadrenarchal children of a restraint upon skeletal maturation. These data suggest that adrenal androgens contribute importantly to epiphyseal advancement during childhood.

Adrenal Cortex↗
PubMed1986

Use of a potent, long acting agonist of gonadotropin-releasing hormone in the treatment of precocious puberty.

Studies utilizing the administration of GnRH in various GnRH-deficient models have revealed the critical importance of the dose and mode of delivery of this releasing factor in determining the subsequent pituitary response. Chronic administration of long acting GnRH agonists (GnRHa), like continuous infusion of high doses of the native peptide, results in suppression of pituitary gonadotropin secretion. This selective and reversible suppression of gonadotropin secretion suggested several therapeutic applications for these analogs, particularly in the treatment of central precocious puberty (CPP), a disorder for which the previously available therapies lacked uniform efficacy and were associated with potential side effects. In our series, 74 children with CPP have been treated during the last 5 yr with the potent GnRH agonist, [D-Trp6, Pro9-ethylamide(NEt)]GnRH. Having selected a dose and route of administration that produced uniform suppression of spontaneous and stimulated pituitary gonadotropin secretion, GnRHa therapy resulted in a fall of gonadal sex steroid levels into the prepubertal range, a halting or regression of secondary sexual development, and a complete cessation of menses. Growth velocity slowed during therapy, with this slowing more pronounced during prolonged treatment periods and among those patients with more advanced chronological and skeletal ages. Skeletal maturation was retarded to a greater degree than linear growth, with resultant increases in the predictions for adult stature. Moreover, these benefits have been achieved in the absence of significant side effects. Complete reversal of the suppression of gonadarche has followed discontinuation of therapy; however, patterns of growth and skeletal maturation after discontinuation of GnRHa administration remain to be characterized. Thus, the impact of GnRHa therapy on final height must await further longitudinal study. The selective nature of GnRHa suppression of gonadarche also permits an investigation of the natural history of adrenarche and its discrete influences upon skeletal growth and maturation. In addition, GnRHa therapy of CPP provides a unique opportunity to study the effects of gonadal sex steroids on GH secretion and somatomedin-C (Sm-C) generation during sexual maturation. Finally, the detailed characterization of children with precocious puberty has helped to define more precisely a subset of patients whose precocity occurs in the absence of demonstrable gonadotropin secretion.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenal Glands↗
PubMed1986

Intravenous administration of pulsatile gonadotropin-releasing hormone in hypothalamic amenorrhea: effects of dosage.

Eighteen women with well characterized hypothalamic amenorrhea underwent 30 cycles of pulsatile GnRH treatment in an effort to examine the role of GnRH dosage in pituitary and ovarian responses. GnRH was administered iv at 2 doses (25 and 100 ng/kg bolus) at a physiological range of frequencies (90 and 60 min) in the follicular phase of the induced cycles. After demonstration of ovulation by ultrasound and clinical parameters, the frequency of GnRH administration was progressively slowed from every 60 min to every 90 min and then to every 240 min to mimic the slowing of endogenous LH secretion that occurs during the luteal phase in normal women. The results of these induced cycles were compared to those of 62 ovulatory cycles from normal women. Overall clinical and biochemical results revealed the following. Patients receiving doses of 25 ng/kg GnRH successfully ovulated only 80% of the time, with recruitment of a single dominant follicle. Two of 5 patients became pregnant. Peak estradiol levels were significantly lower than normal [261 +/- 33 (+/- SE) vs. 342 +/- 11 pg/ml, respectively; P less than 0.02]. Integrated luteal phase progesterone production was also significantly reduced in the 25 ng/kg group compared to normal (78 +/- 17 vs. 145 +/- 8 ng/ml/entire luteal phase, respectively; P less than 0.02). All women receiving bolus doses of 100 ng/kg GnRH ovulated; maturation of multiple follicles occurred in 5 of 20 cycles, and 6 of 7 women conceived. Peak estradiol values were significantly higher than those in either normal women or the 25 ng/kg group (478 +/- 48 pg/ml; P less than 0.02 for both), with integrated luteal phase progesterone levels significantly higher than those in patients receiving the 25 ng/kg dose (196 +/- 25 ng/ml/luteal phase; P less than 0.02). This study demonstrates that ovulation and fertility can be achieved with a physiological frequency regimen of pulsatile GnRH administration using bolus doses of both 25 and 100 ng/kg in women with hypothalamic amenorrhea; the 25 ng/kg dose of GnRH may represent a threshold of stimulation of the pituitary-ovarian axis and recreates cycles with an inadequate luteal phase; and a 100 ng/kg dose of GnRH may well cause a supraphysiological stimulation of the pituitary-gonadal axis.

Amenorrhea↗