FSH Response Research Articles

Role of serotoninergic receptors in gonadotropin secretion in male rats.

Experimental data concerning the role of serotonin (5-HT) in the control of gonadotropins secretion remain controversial: different receptors subtypes should mediate the serotoninergic action. In the present work we analyzed in prepubertal and adult male rats the FSH and LH responses after administration of the following drugs: 5-hydroxy-L-tryptophan (5-HTP), precursor of 5-HT synthesis, the 5-HT1 receptor agonist 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT), the 5-HT2 receptor agonists alpha-methylserotonin maleate (alpha-CH3-HT) and (+/-)-DOI hydrochloride (DOI), the 5-HT3 agonists, quipazine-N-methyldimaleate (QUIP), 2 methyl-serotonin maleate (2-CH3-HT), trimethylserotonin iodide (5-HTQ) and 1-phenylbiguanide (PHE). We found that: a) FSH secretion in adult males was stimulated by 5-HTP, inhibited by 5-HT2 agonists and unaffected by 5-HT3 agonists; b) LH secretion in adult males was stimulated by 5-HTP and alpha-CH3-HT, while DOI and 5-HT3 agonists were ineffective; c) in prepubertal males, 5-HT2 and 5-HT3 agonists inhibited LH release. All these results taken together suggest that: (1) 5-HT2 and 5-HT3 receptors are involved in the control of gonadotropin secretion; (2) FSH and LH secretion are differently modulated by agonists of 5-HT2 and 5-HT3 receptors; (3) the 5-HT2 agonists alpha-CH3-HT and DOI elicit different responses; and (4) the responses obtained vary with animal age, since the inhibitory effect of 5-HT2 and 5-HT3 agonists on LH secretion was observed only in prepubertal males.

Combined beta FSH and beta LH response to TRH in patients with clinically non-functioning pituitary adenomas.

'Paradoxical' responses of LH, FSH, alpha-subunits and beta LH to TRH have previously been reported in individuals with clinically non-functioning pituitary tumours (NFT). The present study was designed to assess the in vivo and in vitro responses of beta FSH to TRH in NFT. We further examined the possibility that a TRH challenge with combined measurement of beta FSH and beta LH will identify a common anomalous secretory pattern in patients with NFT. Forty patients with NFT underwent a standard TRH test (400 micrograms intravenously). Blood samples for the determination of beta FSH, beta LH, FSH and LH were collected prior to TRH as well as 15, 30, 45, 60 and 90 minutes following injection. Additionally, cultured adenomatous cells from eight to these patients were exposed to TRH in the absence and presence of octreotide and gonadotropin subunits were determined. TRH elicited a marked rise in circulating beta FSH in 29 of 40 individuals and in beta LH in 28 of 36 patients with NFT. In a subgroup of eight individuals whose tumours were harvested during surgery and cultured for 7-21 days, TRH increased beta FSH or beta LH and alpha-subunit release in cultured adenomatous cells in all cases, including tumours from subjects not responding to TRH in vivo. In this subgroup of patients octreotide inhibited basal beta FSH secretion but not basal beta LH secretion both in vivo and in primary cultures of NFT cells. Both the in vivo and in vitro beta FSH, beta LH and alpha-subunit responses to TRH were entirely inhibited by octreotide. In all, 38 of the 40 subjects could be identified by either elevated basal beta FSH or beta LH levels and/or an abnormal rise in either beta FSH or beta LH in response to TRH. The measurement of basal and TRH-stimulated beta-FSH and beta-LH levels identifies an abnormal hormonal secretory pattern in the vast majority (> 90%) of patients with clinically nonfunctioning pituitary tumours.

Serum FSH levels in women with polycystic ovary syndrome during ovulation induction using down-regulation and urofollitropin.

To evaluate retrospectively the use of serum FSH levels and to correlate them with follicular growth in a clinical ovulation induction program. Twenty women with infertility due to anovulation associated with polycystic ovary syndrome (PCOS) were studied. The patients were down-regulated with a long GnRH agonist protocol and stimulated with purified urofollitropin, using a low-dose step-up regimen. Repeated serum samples were drawn and transvaginal ultrasound scans were-performed. During the exogenous FSH therapy serum FSH levels resulting in continuous follicular growth were analyzed, as well as the rates of ovulation, pregnancy, cancellation and conversion to in vitro fertilization (JVF). Thirty-two out of fifty treatment cycles led to ovulation, resulting in five term pregnancies. Eight cycles were converted to IVF/embryo transfer due to multiple follicular growth. They resulted in two pregnancies. Ten cycles were cancelled because of impaired follicular growth. The serum FSH levels (median 6 IU/I) resulting in continuous growth of the follicles were relatively stable within patients (variation 15%) but varied considerably between patients (45%). The relationship between FSH dose and serum level was different for lean and obese PCOS patients after subcutaneously injected urofollitropin There seems to be a difference in resorption/metabolism between lean and obese PCOS patients with regard to s.c. injected FSH. The intra-patient coefficient of variation (C.V.) of the serum FSH response level was quite low, as was the C.V. of the FSH dose at the response level. This allowed a more rapid dose adjustment in subsequent cycles. Analysis of serum FSH during induction of ovulation with gonadotropins seems to be of limited value in clinical programs.

EVALUATION OF HYPOTHALAMIC-PITUITARY-GONADAL (HPG) FUNCTION IN PATIENTS WITH TURNER SYNDROME (TS) WITH THE GnRH ANALOG (GnRHa) SUBACUTE TEST

We have previously described that a GnRH test (100 ug of SC Buserelin acetate administered twice at a 24 hs interval) can be used to evaluate the HPG axis in normal prepubertal girls (J Pediat 122:46,1993). In order to evaluate ovarian steroidogenic capacity and the role of sex steroids (SS) in the regulation of pituitary gonadotropins LH and FSH at late prepuberty (Pre), a GnRHa test was carried on in 14 girls with TS and bone ages (BA) between 6.16 and 12 years (y). Serum LH, FSH and E2 was evaluated in basal (B) conditions. 24 hs after the first and 4, 6 and 24 hs after the second injection of Buserelin. A positive response of serum E2 (E2≥55 pmol/L) was only detected in 4 patients. To evaluate LH and FSH responses, patients were divided into 2 groups (Gr) as a function of E2 response: Gr1(E2 ≥55pmol/L), mean±SD chronological age (CA) 9.94±1.84 y and BA 7.41±1.33 y and Gr2 (E2 <55pmol/L, n=10), CA 11.5±3.34 y and BA 9.97±2.49 y. BA was similar in the two groups. B LH and FSH in Gr1 was significantly lower than in Gr2: Median(M) LH was 0.31 (r:0.15-0.49) and 6.79 (r:0.1-54.1) while M FSH was 12.5(r:8.07-17.5) and 43.8(r:8.81-135) U/L, respectively, p<0.05 Dunn's test. Serum LH response to GnRHa was significantly different between Gr1 and Gr2 only 24 hs after the second stimulation (median 1.09, r:0.31-6.6 and 5.1, r:1.21-58, respectively, p<0.05). FSH was similar in the two groups at every sampling time. Conclusions: 1) the GnRHa test in TS is useful to evaluate the steroidogenic capacity of the ovary, 2) lack of difference in FSH response to GnRHa in the two groups would suggest similar ovarian inhibin deficiency, and 3) the differences between Gr1 and Gr2 in B LH and in LH 24 hs after the second GnRHa stimulation suggest that ovarian SS play a role in the regulation of LH secretion in late prepuberty as well as in early puberty.

Growth parameters and endocrine function in relation to echocardiographic parameters in children and adolescents with compensated rheumatic heart disease.

To determine the effect of left ventricular and endocrine functions on linear growth in children with rheumatic heart disease (RHD) we studied 100 children and adolescents with RHD over a period of 1 year. The mean +/- SD for age of onset and duration of RHD were 7.3 +/- 3.8 years and 4.4 +/- 2.8, respectively. The cardiac lesions were mitral incompetence (n = 31), combined mitral and aortic incompetence (n = 64), and mitral stenosis (n = 5). Growth was assessed by determining both height standard deviation scores (HtSDS) and growth velocity standard deviation score (GVSDS) every 4 months, and sexual maturity was assessed according to Tanner's criteria. Two-hundred age-matched normal children served as controls for the growth data. Endocrine evaluation was performed in the 30 children with RHD who had age above 14 years (mean age 15.4 +/- 1.5 years), 20 age- and sex-matched normal children, and 20 age-matched children with constitutional delay of growth (normal variant short stature) (NVSS). Circulating concentrations of estradiol (E2) in girls, testosterone (T) in boys, and free T4 (FT4) were measured. Growth hormone (GH) response to clonidine provocation, LH and FSH response to LHRH stimulation, and in boys testosterone (T) response to HCG were evaluated. Echocardiographic evaluation of the left ventricular parameters was performed using a colour-coded echodoppler. The HtSDS and GVSDS of children with RHD were significantly lower than those for the normal control group. Delayed onset of puberty was evident in 16/30 of the children with RHD, and 6/ 30 more had sexual maturity score below 10th percentile for age and gender. In comparison with the age-matched normal group, those with RHD had significantly lower sexual maturity score (1.8 +/- 0.4 v. 3.25 +/- 0.8). All the children had normal GH response to clonidine provocation and normal FT4 concentrations. Basal and HCG stimulated T concentrations were significantly low in adolescents with RHD and E2 levels were non-significantly lower in girls with RHD compared to normal controls. LH response to LHRH was significantly decreased in RHD patients v. controls denoting delayed maturation of the hypothalamic-pituitary gonadal axis. HtSDS and GVSDS were correlated significantly with the left ventricular echocardiographic parameters, including left ventricular end diastolic diameter (LVEDD) (r = 0.57, and 0.617, respectively; P < 0.01), left ventricular end systolic diameter (LVESD) (r = 0.49, and 0.546, respectively; P < 0.01), left ventricular end diastolic volume (LVEDV) (r = 0.33 and 0.31, respectively; P < 0.05), left ventricular end systolic volume (LVESV) (r = 0.325 and 0.33, respectively; P < 0.05), peak velocity of circumferential fibres (Vcf) (r = 0.25 and 0.38, respectively; P < 0.05), and with pre-ejection period/ejection time (PEP/ET) (r = 0.14 and 0.47, respectively; P < 0.05). It appears that linear growth of children with RHD, without heart failure, depends on the left ventricular function. In addition, they have high incidence of delayed sexual development secondary to delayed maturation of their hypothalamic-pituitary gonadal axis.

Lack of suppressive action of luteal factors from sheep corpus luteum on LH response to exogenous LHRH in ovariectomized, pregnant and post-partum ewes.

In vivo studies have provided evidence of a non-steroidal factor from ovine corpora lutea (CL) of pregnancy called LH-release inhibiting factor (LH-RIF), which specifically inhibits tonic LH release without affecting FSH secretion. To study the possible pituitary site of action of LH-RIF and other factors from sheep CL of pregnancy, the LH response to LHRH was investigated in ovariectomized (OVX) ewes pretreated with ovine luteal extract (oLE) from CL of mid-pregnancy, and in pregnant and post-partum ewes from which the CL were removed at mid-pregnancy. In view of the fact that human follicular fluid (hFF) contains a non-steroidal factor, called gonadotrophin surge-attenuating factor, which attenuates the LHRH-induced LH release, it was clearly important to examine the LHRH-induced LH release in OVX ewes pretreated with oLE or hFF In experiment 1, the LH and FSH responses (the maximum LH and FSH concentrations, the time to maximum LH and FSH concentrations and the area under the LH and FSH response curves) to a single i.v. injection of 5 microg of the LHRH agonist buserelin was not significantly different between ewes pretreated with oLE and ewes pretreated with BSA. Although the LHRH-induced LH and FSH release was slightly attenuated in OVX ewes pretreated with hFF as compared with OVX ewes pretreated with BSA, the maximum LH and FSH concentrations and the area under the LH and FSH response curves were not significantly different between the two groups of ewes. In experiment 2, the LH responses to a single i.v. injection of 0.5 microg LHRH on days 80 and 100 of pregnancy were not significantly different between intact ewes and ewes from which the CL were removed on day 70 of pregnancy. In both groups of ewes the maximum LH concentration and the area under the LH response curve were significantly lower (P <0.02) on day 100 than on day 80 of pregnancy. In experiment 3, the LH responses to a single i.v. injection of 50 microg LHRH on day 140 of pregnancy and on day 10 post-partum were not significantly different between intact ewes and ewes from which the CL were removed on day 70 of pregnancy. In both groups of ewes the maximum LH concentration and the area under the LH response curve were significantly lower (P <0.01) on day 140 of pregnancy than on day 10 post-partum. These experiments provide evidence for a lack of suppressive action of luteal secretory products from the ovine CL of pregnancy on the pituitary LH response to LHRH in OVX, pregnant and post-partum ewes.

Prolactin, gonadotropin, and hair shedding responses to daily sulpiride administration in geldings in winter.

This experiment was designed to determine 1) the efficacy of daily s.c. injections of a dopamine antagonist, sulpiride, for increasing prolactin secretion in geldings in winter and 2) whether increasing prolactin concentrations would hasten the onset of hair shedding or enhance gonadotropin secretion. Five geldings each received vehicle (vegetable oil) or sulpiride (100 mg in vehicle) daily from February 8 through March 29. On February 8 and every 7 d thereafter through March 29, blood samples were drawn around treatment injections and hair samples were collected. On March 30, all geldings received an injection of GnRH and thyrotropin-releasing hormone. Over the 8-wk sampling period, prolactin response to sulpiride varied in a quadratic manner (P < .002). Average area under the 2-h response curve for sulpiride-treated geldings was 24.9 h.ng.mL-1 on February 8, declined to 4.3 after 4 wk, and then increased to 14.8 by the 8th wk of treatment (pooled SE = 4.1 h.ng.mL-1). Prolactin concentrations in control geldings did not vary (P > .1) after injection or over the 8-wk period. Weight of hair pulled from sulpiride-treated geldings did not peak as sharply or as high as that from control gelding (P < .05) and continued to be high through the 11th wk. Sulpiride treatment reduced (P = .071) the LH response to GnRH on March 30; the FSH and prolactin responses to secretagogue were not altered (P > .25). In conclusion, even though prolactin concentrations were increased by sulpiride, the effects on gonadotropin secretion and hair shedding were minor and opposite of those expected.

Effects of passive immunization against inhibin-peptide on secretion of follicle-stimulating hormone and ovulation rate in ewes carrying the Booroola fecundity gene.

Objectives of the study were to determine whether 1) inhibin negative feedback regulation of FSH secretion is diminished in ewes carrying a copy of the Booroola fecundity (FecB) gene and 2) differential FSH secretion is obligatory for expression of gene-specific differences in ovulation rate (OR). The approach was to compare FSH and ovulatory responses to passive immunoneutralization of inhibin in ewes with and without a copy of the FecB gene. Twenty-eight 2- to 3-yr-old ewes were assigned within genotype to antibody (alpha-IF-Ab) or control groups. Genotypes consisted of 3/4 Rambouillet x 1/4 Booroola ewes with one copy of the FecB gene (FecB+; 57 kg) and 3/4 Rambouillet x 1/4 Booroola ewes without the FecB gene (++; 59 kg). Estrus was synchronized during the breeding season using progesterone-releasing pessaries (CIDR-G). Pessaries were removed at 0 h. A single injection of alpha-IF-Ab or control solution was given at -48 h. Alpha-IF-Ab had been developed against a synthetic inhibin fragment matching the N-terminal region of ovine inhibin's alpha subunit. For injection, alpha-IF-Ab had been precipitated from ovine immune sera and concentrated. Blood samples were collected at 6-h intervals from -48 to 48 h, and laparoscopy was performed 14 days after CIDR-G withdrawal. All ewes exhibited estrus and ovulated. Genotype and alpha-IF-Ab treatment were without effect on intervals to estrus. Both factors affected OR (p < or = 0.001). Mean OR in control ++ and FecB+ ewes were 1.6 and 2.7, respectively; mean OR in alpha-IF-Ab-treated ++ and FecB+ ewes were 2.5 and 4.6, respectively. Following injection of alpha-IF-Ab, FSH concentrations increased within 6 h, peaked 12-18 h later, and then declined. Magnitude of FSH increases was similar in ++ and FecB+ ewes (70% and 85% over control values, respectively). Results demonstrate that 1) inhibin negative feedback regulation of FSH secretion is not a site of FecB gene action and 2) the mechanism by which the FecB gene increases OR does not necessarily involve increased FSH secretion during the period of preovulatory follicular development.

Effect of mifepristone (RU486) on the pituitary response to gonadotrophin releasing hormone in women.

Mifepristone interrupts folliculogenesis in women but the mechanism is not clear. Previous studies have investigated the effect of this compound on gonadotrophin secretion and have provided conflicting results. To study further the effect of mifepristone on basal and gonadotrophin-releasing hormone (GnRH)-induced gonadotrophin secretion, 12 normally ovulating women were investigated during two consecutive menstrual cycles, comprising an untreated cycle (control) and a cycle treated with mifepristone. All women were treated with mifepristone on days 2-8 at the dose of 100 mg (group 1, eight women) or 10 mg per day (group 2, six women). Two women were treated with both regimens in two different cycles. On day 8 of both cycles, the women received two GnRH pulses of 10 micrograms each 2 h apart. Blood samples in relation to the first GnRH pulse were taken at-15, 0, 30, 60, 120, 150, 180 and 240 min. In group 1, the increase in luteinizing hormone (delta LH) in response to GnRH was significantly attenuated from 30 to 180 min, while the increase in follicle stimulating hormone (delta FSH) was attenuated only in response to the second GnRH pulse. No significant decrease in delta LH and delta FSH response to GnRH was seen during treatment with the 10 mg dose (group 2). In group 1, serum oestradiol and inhibin-A concentrations after day 8 were lower than in the control cycles and the LH peak was postponed by 7 days on average. Basal LH values increased significantly on day 8 in both groups, while FSH values did not change significantly compared with the control cycles. A significant increase in serum progesterone and cortisol values occurred during the treatment only in group 1. Mid-luteal values of inhibin-A were significantly lower in cycles treated with 100 mg mifepristone than in the control cycles. We conclude that the disruption of folliculogenesis by mifepristone cannot be explained by a decrease in basal FSH concentrations during the critical period of follicle recruitment and selection. It is possible that mifepristone exerts its effect at the level of the ovary. It is also suggested that progesterone during the follicular phase of the cycle may participate in the control of the self-priming action of GnRH on the pituitary.

The GnRH challenge test: a quantitative measure of pituitary desensitization during GnRH agonist administration

The use of GnRH agonists for desensitization of the pituitary is widespread in gynaecological practice. For indications such as contraception and treatment of uterine leiomyomata partial desensitization may suffice. With respect to partial desensitization of the pituitary we have addressed three basic questions: (1) Is the degree of pituitary desensitization dependent on the dose of agonist used? (2) What is the optimal way to measure the degree of pituitary desensitization? (3) Is it possible to create a standard to express the degree of pituitary desensitization? Twenty-four women were randomized into 4 groups of 6 women. To achieve pituitary desensitization, the groups received 0.1, 0.25, 0.5 and 1.0 microgram/min GnRH respectively, for 6 weeks. Pituitary desensitization was measured by gonadotrophin levels and responses to a 100-micrograms bolus of GnRH and an oestradiol benzoate challenge-test. The level of LH and the responses of LH and FSH to the GnRH challenge showed significant dose-dependent suppression. Multiple regression indicated the LH response to the GnRH challenge was the best way to measure pituitary desensitization. From the LH responses to the GnRH-challenge a 'standard curve' was established for the assessment of the degree of pituitary desensitization. The LH response to the GnRH challenge test is the best available measure of pituitary desensitization during GnRH agonist treatment.

Gonadotropin therapy in males with hypogonadotropic hypogonadism: factors affecting induction of spermatogenesis after gonadotropin replacement.

Sixteen patients with hypogonadotropic hypogonadism received gonadotropin replacement therapy. Two patients treated with HCG alone showed induction of spermatogenesis 2 and 12 months after the start of treatment. Three subjects receiving combination therapy showed sperm appearance 6-28 months after treatment. The patients showing sperm appearance, whose testicular volume was > or = 4 ml, showed a higher sperm count and impregnated their partners, although no relationship was found between pretreatment testicular volume and sperm appearance. The response to HCG test correlated with sperm appearance after gonadotropin therapy. Sperm appearance was not observed in any subject except for one who showed no response to luteinizing hormone-releasing hormone (LH-RH) test and none of the patients without response of FSH to LH-RH demonstrated any induction of spermatogenesis. In conclusion, the responses to LH-RH test and possibly to HCG test could predict the induction of spermatogenesis after gonadotropin replacement therapy, and a large testicular volume is associated with post-treatment fertility.

Influence of Hypothalamus and Ovary on Pituitary Function in Transgenic Mice Expressing the Bovine Growth Hormone Gene and in Growth Hormone-Deficient Ames Dwarf Mice1

Female transgenic mice expressing the bovine (b) growth hormone (GH) gene exhibit reduced fertility, and GH-deficient dwarf mice are sterile. However, in these animals, the influence of the hypothalamus and ovary on pituitary functions is poorly understood. To address this issue, female Ames dwarf mice received twice-daily injections of either vehicle or bGH (25 micrograms/injection per mouse) for 12 days. Vehicle-injected normal female siblings served as controls. On Day 7, these mice and adult female transgenic mice expressing the bGH gene with mouse metallothionein-I promoter, as well as their normal littermates, were ovariectomized. Two experiments were conducted with each group of mice: on Day 8 after ovariectomy of transgenic mice and their normal siblings, and on Day 4 after ovariectomy of dwarf mice and their normal siblings. In experiment I, mice were primed with 0.5 micrograms estradiol benzoate (EB) in oil and 24 h later received injections of 5 micrograms EB/100 g BW. The next day, these mice received injections of either saline or GnRH (1 ng/g BW), and 15 min later blood was obtained via heart puncture under anesthesia. In experiment II, ovariectomized mice either received injections of oil or were primed with 0.5 micrograms EB and 24 h later treated with 10 micrograms EB/100 g BW in oil. On the next day, blood was obtained as in experiment I. In transgenic mice and in their normal littermates, plasma bGH, FSH, LH, and prolactin levels were measured. In dwarf mice and in their normal siblings, plasma LH and insulin-like growth factor (IGF)-I levels were determined. Bovine GH was secreted in transgenic mice, but this hormone was not detectable in normal siblings. Expression of the GH gene resulted in attenuated (p < 0.001) FSH response to GnRH treatment, while LH response was similar to that in controls. The ovariectomy-induced increases in plasma FSH (p < 0.001) and LH (p < 0.05) levels were decreased in transgenic mice. The absolute circulating FSH levels were also decreased (p < 0.001) in estrogen-treated transgenic mice, while plasma LH level were similar in normal mice and in mice bearing the bGH gene. The ovariectomized transgenic mice were hyperprolactinemic. In ovariectomized dwarf mice, IGF-I was not detectable, and GH treatment induced its secretion. In these mice, plasma LH concentrations were reduced (p < 0.05), and GH treatment increased (p < 0.01) LH secretion. In oil-injected ovariectomized dwarf mice, the plasma LH response to GnRH treatment was reduced (p < 0.001), and GH administration normalized this response. The negative feedback effect of estrogen on LH secretion was decreased (p < 0.025) in dwarf mice. These indicate that the alterations in gonadotropin secretion are dependent on the duration of exposure of neuroendocrine system to bGH and that bGH alters the effects of GnRH and estrogen on gonadotropin secretion in these two widely divergent experimental mouse models.

Fourier analysis of differential light scattering for the quantitation of FSH response associated with structural changes in immortalized granulosa cells

We have established granulosa cell lines which express constitutively the rat FSH receptors by cotransfection of primary granulosa cells obtained from preovulatory follicles with SV40 DNA, Ha- ras oncogene and a plasmid expressing FSH receptors. These cells respond specifically to ovine and human FSH by cell rounding, intracellular cAMP accumulation, and progesterone secretion in a dose-dependent manner. A new method for the demonstration and quantitation of changes in cell shape — Small Angle Laser Light Scattering (SALLS) analysis — has been utilized for measurement of cell rounding in response to FSH stimulation in these cells. When cells were incubated with increasing doses of either ovine or human FSH, partial rounding of cells was observed at FSH concentrations as low as 24 pM, while complete rounding of cells was observed at a range of 0.24–2.4 nM of FSH. Following aldehyde fixation, hormone-treated cells were examined using the method of SALLS analysis. Histograms obtained by applying SALLS analysis on FSH stimulated GFSHR-17 cells were a reflection of the structural changes induced by the hormone. FSH- and forskolin-incubated cells yielded structured distributions with defined mean size and standard deviations. Moreover, the increase in sharpness of dominant peak in the histogram was correlated with elevated concentration of FSH in a dose dependent manner. In conclusion, cellular response to FSH is correlated with a specific pattern of light scattered in immortalized granulosa cells expressing functional FSH receptors. Therefore, SALLS analysis may serve as a useful tool for in vitro bioassay of the gonadotropic hormone. Moreover, this method may lend itself to in vitro bioassay of any hormone that induces specific morphological changes in target cells.

Treatment of central precocious puberty: comparison of urinary gonadotropin excretion and gonadotropin-releasing hormone (GnRH) stimulation tests in monitoring GnRH analog therapy.

GnRH analogs (GnRH-a) have proven to be efficacious and have become the standard treatment for central precocious puberty (CPP). To confirm the diagnosis of CPP and to monitor the adequacy of hvpothalamic-pituitary-gonadal (HPG) axis suppression, GnRH stimulation testing has been essential. To determine whether 24-h urinary gonadotropin excretion could adequately assess HPG axis suppression, we compared the results of simultaneous GnRH stimulation tests and 24-h urinary gonadotropin determinations in 18 girls with CPP who were receiving GnRH-a therapy (leuprolide acetate, Depot-Lupron, TAP Pharmaceuticals). HPG axis suppression was defined as the absence of significant LH and FSH responses to GnRH stimulation. Simultaneous GnRH stimulation tests and urinary gonadotropin determinations had a concordance rate of 68% (42 of 62). The sensitivity and specificity of urinary LH determinations to detect inadequate HPG suppression were 75% and 64%, respectively. For urinary FSH determinations, the sensitivity and specificity were 90% and 28%, respectively. Hence, single timed urine collections lacked the sensitivity and specificity to assess HPG axis suppression and, thus, cannot replace GnRH stimulation tests for monitoring the adequacy of the GnRH-a dose.

Pituitary-ovarian responses to leuprolide acetate testing in patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency.

To assess whether patients with congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency exhibit a steroidogenic response to GnRH agonist consistent with functional ovarian hyperandrogenism (FOH) and elucidate the relationship between adrenal and ovarian hyperandrogenism, the LH, FSH, estradiol, 17-hydroxyprogesterone (17-OHP), androstenedione, total testosterone, dehydroepiandrosterone, and 17-hydroxypregnenolone responses to a sc dose of leuprolide acetate (500 micrograms) were evaluated in 10 patients with classic CAH (mean age, 18.4 +/- 0.95 yr), 7 of whom had oligomenorrhea, pretreated with dexamethasone (2 mg/day for 5 days, including the day of the test). The results were compared with those obtained in 11 patients with FOH (mean age, 18.7 +/- 0.46 yr) and 17 normal women (mean age, 19.68 +/- 0.59 yr) not pretreated with dexamethasone. Leuprolide acetate stimulation caused a significant augmentation of plasma E2, 17-OHP, androstenedione, testosterone, and 17-hydroxypregnenolone concentrations in all CAH patients. However, in only 6 (60%) of them, all with oligomenorrhea, was the 17-OHP response (posttest minus pretest value) similar to that of FOH patients and significantly higher than that in controls. In this subset of CAH patients, LH plasma levels after stimulation were significantly higher than those of CAH subjects with 17-OHP responses in the normal range, controls, and FOH patients, whereas FSH levels were similar to those of controls. In this latter group, plasma FSH concentrations after stimulation were significantly higher than those in FOH. In conclusion, the results of the present study indicate that LH-dependent functional ovarian hyperandrogenism is frequent in patients with classic CAH. As ovarian hyperandrogenism might be partially responsible for the menstrual irregularities that are common complications in such patients, all classic CAH patients with oligomenorrhea should undergo short term stimulation with GnRH agonists to ascertain the presence of ovarian hyperandrogenism and receive appropriate treatment.

Serum hormone concentrations during treatment with multiple rising doses of recombinant follicle stimulating hormone (Puregon ) in men with hypogonadotropic hypogonadism

To study increases of serum FSH and gonadal response in gonadotropin-deficient men treated with recombinant FSH (Puregon; NV Organon, Oss, The Netherlands).An open, prospective, multiple rising dose study in which volunteers received single daily IM doses of recombinant FSH for 3 weeks. The dose administered was increased at weekly intervals: the first 7 days, 75 IU/d; the subsequent 7 days, 150 IU/d; and the last 7 days, 225 IU/d.Nine men suffering from isolated gonadotropin deficiency or panhypopituitarism.Immunoreactive FSH, LH, inhibin, T, and androstenedione.Serum immunoreactive FSH (median) rose in accordance with the recombinant FSH doses administered from 0.5 mIU/mL (range < 0.05 to 1.9 mIU/mL) at baseline to 4.3 mIU/mL (range 2.0 to 8.5 mIU/mL), 8.4 mIU/mL (range 4.9 to 17.8 mIU/mL), and 13.6 mIU/mL (5.6 to 28.4 mIU/mL) after 1, 2, and 3 weeks of medication, respectively. The elimination half-life of recombinant FSH was 48 +/- 5 hours (mean +/- SD), which was slightly longer than that reported after single dose administration of recombinant FSH (32 +/- 12 hours). The bioactivity of recombinant FSH was reflected by serum inhibin levels, which rose from 116 U/L (range 34 to 356 U/L) at baseline to 350 U/L (range 63 to 1,109 U/L) at day 22. However, serum FSH and inhibin levels did not correlate when compared after 1, 2, and 3 weeks of recombinant FSH administration. Serum immunoreactive LH, T, androstenedione, and E2 were 0.2 mIU/mL (range < 0.05 to 0.7 mIU/mL [conversion factor to SI unit, 1.0]), 58 ng/dL (range < 12 to 222 ng/dL [conversion factor to SI unit, 0.0347]), 14 ng/dL (range 6 to 115 ng/dL [conversion factor to SI unit, 0.0349]), and 14 pg/mL (range < 14 to 16 pg/mL [conversion factor to SI unit, 3.67]), respectively, at baseline and remained unchanged during the entire treatment period.These data indicate that recombinant FSH treatment increases serum FSH in a dose-proportional fashion, increases inhibin secretion, and lacks intrinsic LH activity.

Contour of the GnRH pulse independently modulates gonadotropin secretion in the human male.

GnRH pulse frequency, amplitude, and interpulse interval have all been demonstrated to regulate gonadotropin secretion individually. We tested the hypothesis that the contour of the GnRH pulse also modulates gonadotropin output in 10 men with isolated GnRH deficiency in whom a fixed GnRH dose was administered at a constant physiologic frequency by either instantaneous bolus or by 1-, 5-, or 30-min infusions. LH, FSH and free alpha subunit (FAS) responses were also compared to spontaneous gonadotropin secretion in normal adult men. While the LH and FAS pulses following the instantaneous bolus and 1-min infusion of GnRH were indistinguishable, further increases in the duration of gonadotrope stimulation by GnRH were associated with progressive decreases in all parameters of gonadotropin secretion (mean levels, amplitude, peak levels, AUC). FSH secretion was also decreased following variations in the contour of the GnRH pulse, although overall changes were less dramatic than for LH and FAS. The LH pulses following the bolus GnRH stimulation were indistinguishable from spontaneous LH pulses occurring in normal men whereas those stimulated by the 1-, 5-, and 30-min infusions of GnRH became progressively blunted with the lowest levels of secretion occurring after the longest infusion. In sharp contrast, FAS pulse parameters in the GnRH-deficient subjects greatly exceeded those of normal men regardless of the contour of the GnRH stimulus, whereas mean FSH levels were all modestly (although significantly) higher than those of normal adult men. These results demonstrate that the pituitary is sensitive to subtle changes in the contour of the GnRH stimulus, with a more prolonged duration of GnRH stimulation resulting in a diminished pituitary response. Alterations of the contour of endogenous GnRH secretion may represent an additional mechanism for altering gonadotrope function and provide additional evidence for the differential regulation of LH, FAS, and FSH by GnRH. However, the previously reported elevated levels of FAS secretion in GnRH-deficient men undergoing long-term GnRH replacement are not explained by abnormalities of GnRH contour.

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

To evaluate the impact of chronic GnRH antagonist therapy on the extent of GnRH agonist-induced gonadotrope desensitization. Prospective and controlled. Primate Research Center. Six reproductive age cycling female baboons (Papio cyanocephalus anubis). 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. 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. 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. The presence of GnRH antagonist reduces the extent of gonadotrope desensitization in response to the administration of repetitive pulses of GnRH agonist.

Immunoneutralization of Inhibin and Estradiol during the Follicular Phase Of the Estrous Cycle in Cows1

To investigate the physiological importance of inhibin and estradiol in the regulation of FSH secretion during the follicular phase of the estrous-cycle in cows, animals were passively immunized against the two hormones. Sixteen cows were divided into four equal groups and given injections of prostaglandin F2 alpha (PG) i.m. twice at 8-h intervals on Day 10 of the estrous cycle (Day 0 = day of estrus) to induce luteal regression. At 48 h after the first PG injection, each group of four cows received injections of one of the following: 100 ml castrated goat serum (control serum), 100 ml antiserum against inhibin, 100 ml antiserum against estradiol, or a combination of 100 ml inhibin antiserum and 100 ml estradiol antiserum. The LH surge occurred within 2 days after injection of the control serum or inhibin antiserum, whereas it was not detected in either of the groups passively immunized against estradiol, indicating that passive immunization against estradiol blocks a positive feedback effect of estradiol on LH secretion. There was no clear difference in basal concentrations of LH among the four groups. Injection of the inhibin antiserum resulted in a marked increase (p < 0.01) in plasma concentrations of FSH compared with values in the control group, while there were no significant changes in concentrations of plasma FSH after injection of the estradiol antiserum. Combined administration of the inhibin and estradiol antisera also produced a marked increase (p < 0.01) in plasma concentrations of FSH. The FSH response to the combined immunization was longer in duration than the FSH response to immunization with inhibin alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Blockade of Singular Follicle-Stimulating Hormone Secretion and Testicular Development in Photostimulated Djungarian Hamsters (Phodopus Sungorus) by a Gonadotropin-Releasing Hormone Antagonist1

Photostimulated male Djungarian hamsters following placement in a long-day photoperiod exhibit a characteristic rise in serum FSH levels that occurs in the absence of a simultaneous rise in LH levels. It is not known whether this singular FSH secretion is dependent upon a differential responsiveness of the gonadotrophs to the pattern of pulsatile GnRH release or is instead driven by a GnRH-independent mechanism. We have assessed the GnRH dependence of this singular FSH secretion by testing the ability of a potent GnRH antagonist (GnRHa: WY-45760) to block FSH and testicular responses to photostimulation. Photoinhibited hamsters were transferred from a short-day (6L:18D) to a long-day photoperiod (16L:8D). Hamsters received two daily injections of a GnRH antagonist or vehicle (VEH). After 0 (short day), 3, 5, 10, 30, or 40 days the hamsters were killed; plasma was assayed for FSH, LH, and testosterone (T), and testes weights were recorded. Testes were sectioned and analyzed for tubular development. In VEH-treated animals, testicular weights increased after photostimulation, reaching mean values of 514 mg by 30 days. Treatment with GnRHa resulted in a significant (p < 0.01) attenuation of testicular growth after 30 days of photostimulation (mean testes weight = 110.1 mg). In VEH-treated hamsters there was a rapid increase in FSH levels after photostimulation that became significant by 5 days and peaked at 10 days. In the GnRHa-treated group, however, these FSH increments were completely blocked at 5 days and significantly reduced at 10 days compared to the values in the corresponding VEH-treated groups.(ABSTRACT TRUNCATED AT 250 WORDS)