Serum Bioactive FSH Research Articles

Analysis of serum FSH bioactivity in a patient with an FSH-secreting pituitary microadenoma and multicystic ovaries: A case report

FSH-secreting pituitary adenoma (FSHoma) is often associated with increased levels of serum FSH and ovarian hyperstimulation syndrome (OHSS). The OHSS has historically been attributed to elevated FSH production by the FSHoma; however, some FSHoma patients with OHSS have normal serum FSH levels. OHSS may result not from increased FSH levels, but also from increased bioactivity of the FSH derived from the adenoma. To address this, we measured the FSH bioactivity in the serum of a 40-year-old woman with an FSHoma and OHSS, whose FSH levels were normal. Chinese hamster ovary cells stably expressing FSH receptors were prepared and transfected with a cAMP-responsive element-driven luciferase reporter plasmid. Cells were then treated with recombinant human FSH (rhFSH), the patient's sera, or sera from controls, collected at different time points, and subjected to a luciferase assay. Luciferase activity was increased in response to rhFSH in a dose-dependent manner. The responsiveness was further augmented by co-addition of a 3-methyl isobutylxanthine, which improved the sensitivity of our assay. Unexpectedly, the serum FSH bioactivity/immunoactivity ratio of the patient was mostly equal to that of normal subjects. This was confirmed with a granulosa cell aromatase assay. This case report suggests that alternate explanations may exist for the OHSS phenotype seen in some FSHoma patients.

In vitro biological-to-immunological ratio of serum gonadotropins throughout male puberty in children with insulin-dependent diabetes mellitus

Information on the impact of prolonged deficient glycemic control in the quality of the gonadotropin signal delivered by the pituitary gland during puberty in children with insulin-dependent diabetes mellitus (IDDM) is scarce. In the present study, we examined the impact of deficient glycemic control on bioactive LH and FSH concentrations and their corresponding biological-to-immunological (B:I) ratio in boys with poorly controlled, but systemically uncomplicated IDDM. Dual control groups comprising patients with well-controlled IDDM and healthy boys of comparable age and body mass index were included for appropriate comparisons within and between each pubertal stage. Patients with poorly controlled and well-controlled IDDM exhibited serum bioactive FSH levels and B:I FSH ratio similar to those showed by the healthy control group. In contrast, in early and mid-pubertal boys with poorly controlled IDDM bioactive LH levels were normal, but its B:I LH relationship was significantly (P < 0.05) decreased. This attenuation in the quality of the LH signal did not affect total serum T concentrations, and apparently, progression of puberty. Long-standing uncontrolled diabetes and the consequent metabolic disturbances and/or complications may aggravate the reproductive axis dysfunction and eventually provoke pubertal arrest.

Basal and gonadotropin-releasing hormone-releasable serum follicle-stimulating hormone charge isoform distribution and in vitro biological-to-immunological ratio in male puberty.

Follicle-stimulating hormone is synthesized and secreted as a mixture of heterogeneous isoforms that differ from each other in carbohydrate structure, biological potency, and plasma half-life. The relative abundance of the FSH isoforms will depend on the endocrine status of the donor at the time of sample collection. In the present study, we attempted to define the impact of the changing endocrine milieu characteristic of male puberty on the charge heterogeneity and plasma half-life of the serum FSH isoforms released under endogenous and exogenous GnRH drives, and examined whether such a varying hormone milieu modifies the capability of the circulating hormone to trigger intracellular signal transduction at the human FSH receptor level. Forty healthy male subjects at Tanner stages (Ts) 1 to 5 were sampled at 10 min intervals for 10 h. Serum from successive samples collected across 2-4 h intervals containing FSH released under basal, low-dose (10 microg), and high-dose (90 microg) exogenous GnRH-stimulated conditions was subjected to preparative chromatofocusing and tested for bioactivity employing a homologous cell in vitro bioassay system. Deconvolution analysis was applied to estimate the apparent endogenous FSH plasma half-life in samples obtained after administration of low-dose exogenous GnRH. Under all conditions studied, serum FSH charge isoforms were distributed along a pH range of 7.0 to less than 3.0. Comparisons across the different Tanner stages revealed a significant and selective increase in the ratio of FSH isoforms with elution pH values <4.50 relative to those with values >/=4.50 at Ts-2. At Ts-3, this ratio returned to that present at Ts-1, to decline thereafter during the ensuing pubertal stages. Serum bioactive FSH concentrations progressively increased (from 3.72 +/- 1.3 to 16.2 +/- 5.3 IU/L) throughout puberty, and in all conditions bioactive FSH concentrations exceeded those detected by a specific radioimmunoassay. The biological to immunological (B:I) FSH ratio at baseline was significantly (p < 0.05) lower at Ts-1 and Ts-2 (1.33 +/- 0.30 and 1.62 +/- 0.34, respectively) than at more advanced stages of pubertal development (2.28 +/- 0.20, 2.96 +/- 0.38, and 2.77 +/- 0.63 at Ts-3-, 4-, and -5, respectively) Similar differences were detected in samples containing FSH molecules released after low- and high-dose GnRH administration. The apparent endogenous FSH half-life of the deconvolved GnRH-induced FSH pulses was similar in the five study groups. These results demonstrate that the transition from infancy to sexual maturity in men is accompanied by qualitative changes in the circulating FSH isoform mixture. Although the changes in FSH glycosylation occurring throughout puberty are not of sufficient magnitude to alter the survival of the gonadotropin in circulation, they allow preferential secretion of bioactive FSH. The enrichment of the circulating mix of FSH isoforms with highly bioactive variants throughout spontaneous puberty may potentially favor the development of spermatogenesis and acquisition of reproductive competence.

Serum FSH bioactivity and inhibin levels in patients with gonadotropin secreting and nonfunctioning pituitary adenomas.

It has been reported that serum FSH bioactivity and inhibin levels can be used as markers of the presence of true gonadotropin-secreting pituitary adenoma (Gn-oma). To verify this hypothesis, we have investigated the bioactivity of FSH and serum inhibin alpha-alpha and alpha-beta A levels in a series of patients with either Gn-oma or nonfunctioning pituitary adenoma (NFPA). Nine patients with Gn-oma (6 men and 3 women), 21 with NFPA (9 men and 12 women) and 30 normal subjects were included in the study. We studied FSH biological activity (FSH-B) by using Sertoli cell aromatase bioassay (SAB) and alpha-alpha and alpha-beta A inhibin levels by two noncompetitive immunometric assays (IEMA). In male patients with Gn-oma, serum immunoreactive FSH (FSH-I) and FSH-B levels ranged from 5.1 to 35.5 U/L and from 8.3 to 48 U/L, respectively, FSH B/I ratio being elevated in 2 (2.5 and 4.1; normal male range: 0.3-1.5), while female patients with Gn-oma had serum FSH-I and FSH-B levels ranging from 43.2 to 162 U/L and from 41.2 to 112.8 U/l, respectively, with a normal FSH B/I ratio. In male patients with NFPA, FSH-I and FSH-B levels ranged from 2.7 to 10.7 U/l and from 2.4 to 11.4 U/l while in females they ranged from 3.4 to 67.9 and from 4.6 to 60.8 U/l, respectively. FSH B/I ratio was elevated in 1 male (3.3) and normal in the remaining patients with NFPA. Serum alpha-alpha inhibin levels were normal or low in patients with Gn-oma and NFPA, while alpha-beta A inhibin concentrations were slightly elevated in 1 of 6 postmenopausal women (0.9; normal range < 0.7 U/ml). The present study confirms and extends previous reports indicating that male patients with Gn-oma may secrete FSH molecules with increased bioactivity. However, this abnormality was also observed in one male patient with NFPA. Moreover, the measurement of inhibin levels does not appear to be a reliable in vivo marker of pituitary tumors of gonadotroph origin, as it was normal or low in almost all patients with either Gn-oma or NFPA.

In Vitro Sertoli Cell Bioassay of Follicle-Stimulating Hormone (FSH): Serum from Different Animal Species Alters the Morphology of Rat Sertoli Cells without Affecting Their Response to FSH

Follicle-stimulating hormone (FSH) stimulates aromatase activity of immature rat Sertoli cells cultured in vitro in the presence of an androgen substrate, a phenomenon that can be used to measure FSH bioactivity. This paper analyzes the effects of sera from various animal species on both aromatase activity and morphological aspects of cultured rat Sertoli cells. Treatment of Sertoli cells with increasing concentrations of serum from humans, monkeys, rats, hamsters, and mice gave a dose-dependent stimulation of estradiol production parallel to the response obtained with FSH standard. Serum from these species and from rabbits also had a characteristic morphological effect on the cells, to produce a fibroblast-like aspect and clumping. This effect was dose-dependent, was increased by the addition of FSH, and was eliminated by heating the sera at 56° for 30 min prior to incubation with the cells. Clumping did not interfere with the aromatase activity of Sertoli cells and did not cause the cellular response to deviate from parallelism with the standard curve. Heat treatment of FSH standard and serum samples did not significantly change the aromatase activity. FSH bioactivity could be measured accurately in intact and castrated monkeys. It is concluded that the Sertoli cell aromatase bioassay can be applied directly to the measurement of serum bioactive FSH in several animal species without any preliminary treatment of the serum samples.

Serum Bioactive Luteinizing and Follicle-Stimulating Hormone Concentrations in Girls Increase during Puberty

FSH plays an essential role in folliculogenesis and ovarian growth. However, cross-sectional studies have not shown an increase in bioactive FSH (B-FSH) during puberty. To eliminate intersubject variability, we used a longitudinal design and tested the hypothesis that B-FSH increases during puberty. Thirty normal, healthy girls were enrolled in a longitudinal study from pubertal stages I to IV. The subjects were evaluated at 6-mo intervals; each visit consisted of pubertal staging, bone age determination by x-ray, measurements of serum immunoreactive FSH (I-FSH) and B-FSH (n = 14) or immunoreactive LH (I-LH) and bioactive LH (B-LH) (n = 18), and adrenal and ovarian steroids. All girls had clinical and hormonal characteristics of puberty. Both I-FSH and B-FSH levels were relatively elevated before puberty, whereas serum I-LH and B-LH were low. From pubertal stages I to III, there was a modest yet significant rise in serum I-FSH (p < 0.001) and serum B-FSH (p < 0.01). Serum I-LH and B-LH concentrations showed the expected increases with puberty (p < 0.001), with serum B-LH concentrations exhibiting a greater rise than I-LH (p < 0.001). Our results demonstrate that serum B-FSH and I-FSH increase during puberty. Relatively elevated B-FSH concentrations from early to midpuberty may be an important factor for ovarian growth while circulating LH and estrogen are still low. As puberty progresses, the continued and selective increase in LH induces a rise in estradiol and ultimately leads to ovulation.

Serum FSH Bioactivity and Response to Acute Gonadotrophin-Releasing Hormone Agonist Stimulation in Patients With Polycystic Ovary Syndrome (PCOS) as Compared to Control Groups

Serum FSH Bioactivity and Response to Acute Gonadotrophin-Releasing Hormone Agonist Stimulation in Patients With Polycystic Ovary Syndrome (PCOS) as Compared to Control Groups

NOCTURNAL BIOACTIVE FSH PULSES ARE EVIDENT IN PRE (PERI) PUBERTAL BOYS

Secretion of both LH and FSH is pulsatile and maximal during the night in early peripubertal boys. To evaluate the pulsatile pattern of bioactive FSH (B-FSH), we assessed serum concentrations of B-FSH in four Tanner Stage I boys with constitutional growth delay (mean age 15y 3m, mean bone age 12y 6m) and compared their data to previously published data from 6 Tanner Stages II-III pubertal boys (Hassing et al, JCEM, 1990, 70:1082). Each of the four boys had a 12 h overnight blood sampling (every 20 min) followed by administration of 1μg/kg nafarelin sc. Serum I-LH and I-FSH were measured by RIA and B-FSH was measured by the rat Sertoli cell aromatase induction assay using hLH-13 and hFSH-13 standards and expressed as ng/ml. The mean serum I-LH, I-FSH and B-FSH were 0.63±0.06, 0.40±0.15 and 1.8±0.2 ng/mL (p<0.05, B vs I FSH). B-FSH pulse frequency was similar to I-LH pulse frequency (0.43±0.1 and 0.43±0.05 pulses/boy/h) and to previously published data in mid pubertal boys. ΔI-LH release was 3.3±0.7, ΔI-FSH was 2.4±0.6 and ΔB-FSH was 4.2±1.4 ng/mL. We conclude that during the peripubertal period in boys, serum B-FSH is secreted in a pulsatile manner and the concentrations exceed those of serum I-LH or I-FSH.

Pulsatile administration of gonadotropin-releasing hormone does not alter the follicle-stimulating hormone (FSH) isoform distribution pattern of pituitary or circulating FSH in nutritionally growth-restricted ovariectomized lambs.

The experimental induction of puberty by GnRH administration to prepubertal lambs increases serum bioactive FSH (B-FSH) as measured in the rat Sertoli cell aromatase induction bioassay. Serum immunoreactive FSH (I-FSH) levels are unchanged. The increase in serum B-FSH is associated with an increase in the proportion of less acidic and more biopotent FSH serum isoforms. However, it is unknown if this effect of GnRH on serum FSH microheterogeneity is direct or mediated by gonadal factors. We have used the nutritionally growth-restricted ovariectomized lamb as a model of the neuroendocrine regulation of FSH isoform microheterogeneity. With this model, the hypothalamic-pituitary component of the neuroendocrine axis may be isolated from gonadal factors. In the present study, using the nutritionally growth-restricted ovariectomized lamb as a model, we investigated the role of GnRH on the regulation of FSH microheterogeneity. Specifically, we tested the hypothesis that GnRH increases the proportion of the less acidic (more biopotent) serum FSH isoforms. As an in vitro correlate, we investigated the effect of GnRH on gonadotropin secretion and FSH isoform distribution in ovine pituitary explant cultures. Seven ovariectomized nutritionally restricted lambs were administered GnRH (i.v., 2 ng/kg) for 36 h (at 2-h intervals for 24 h, then hourly for the final 12 h). Six others served as controls. Blood samples were withdrawn at 12-min intervals during the last 4 h for the measurement of serum immunoactive LH (I-LH) and I-FSH. Pituitary homogenates and serum from four animals from each group were individually chromatofocused, and the FSH isoform distribution patterns were determined. Pulsatile administration of GnRH to nutritionally growth-restricted lambs increased circulating I-LH concentrations from 0.6 +/- 1.0 to 5.9 +/- 3.1 ng/ml (P < 0.01), but did not significantly change circulating I-FSH (4.9 +/- 1.8 vs. 11.5 +/- 4.2 ng/ml) nor B-FSH concentrations (3.9 +/- 1.2 vs. 5.7 +/- 1.5 ng/ml). The pituitary content of I-FSH, B-FSH, and I-LH were unchanged. Neither serum nor pituitary FSH isoform distribution patterns were altered by pulsatile GnRH administration. However, compared to the pituitary FSH isoforms, a higher percentage of circulating FSH isoforms eluted in the salt peak of both groups of lambs. Similar to the in vivo studies, in vitro, GnRH increased the release of I-LH, as well as I-FSH, from pituitary explants, but did not significantly change the FSH isoform distribution in either the pituitary explant or media.(ABSTRACT TRUNCATED AT 400 WORDS)

Serum FSH bioactivity and response to acute gonadotrophin releasing hormone (GnRH) agonist stimulation in patients with polycystic ovary syndrome (PCOS) as compared to control groups

We evaluated the biological activity of FSH in the serum of women with polycystic ovary syndrome before and after acute administration of a GnRH agonist as compared to control groups. FSH, oestradiol and androstenedione response to buserelin (100 micrograms s.c.) comparing seven polycystic ovary patients, six idiopathic hirsute women, 11 normal women in the follicular phase and nine normal men. Rat granulosa cell aromatase bioassay in the presence or absence of polyethyleneglycol (PEG) pretreated 2% serum. Serum biological FSH (B-FSH), immunological FSH (I-FSH) and B/I ratio at times 0, 1, 2, 3, 4, 8, 12 and 24 hours. Serum androstenedione and oestradiol at times 0 and 24 hours. Human gonadotrophin-free (oral contraceptive user and after FSH immunoabsorption) and PEG-pretreated serum increases the aromatase activity in response to increasing doses of purified FSH. The maximum enzymatic activity is however higher with 2% serum than with 4% serum. The amplitude of the B-FSH response to the GnRH agonist is markedly decreased in the polycystic group as compared to the group of normal women. There is also a small decrease in the I-FSH response in the polycystic women. When compared to that of normal women, the area under the curve in the polycystic ovary patients is reduced by 71% for B-FSH (P < 0.01) and by 23% for I-FSH (P < 0.05). The B-FSH and I-FSH responses in men are very small. After an initial decrease the B/I ratio returns to baseline level in normal women but remains low in the other groups. At time 24 hours, there is no significant change in the serum concentration of androstenedione but serum oestradiol, the baseline of which is significantly higher in the polycystic patients than in normal women, is also significantly higher at 24 hours (P < 0.05) in response to the pharmacological release of FSH. The gonadotrophin-free and PEG-pretreated human serum has an inherent stimulatory effect on the rat granulosa aromatase bioassay with a higher activity at 2% serum. Acute GnRH agonist stimulation reveals a deficiency in the FSH response in polycystic ovary patients. The greater deficit in B-FSH than in I-FSH would indicate a possible modification in the FSH isoforms in this syndrome. The meaning of this observation for the understanding of the physiopathology of the polycystic ovary syndrome remains to be evaluated.

Effects of follicular fluid administration on serum bioactive and immunoactive FSH concentrations and compensatory testicular hypertrophy in hemicastrated prepubertal rats

In prepubertal rats, removal of one testis (hemicastration) results in increased FSH secretion and a compensatory hypertrophy of the remaining testis. To determine whether these two events are related, testis weight was measured after inhibin-rich porcine follicular fluid (FF) was administered to hemicastrated rats twice daily for 14 days to block the compensatory rise in FSH. After hemicastration, serum immunoreactive FSH concentration approximately doubled and testis weight was increased by approximately 60%. A slight but non-significant increase in serum bioactive FSH was also observed. Treatment of hemicastrated rats with FF completely prevented the increase in serum FSH and compensatory growth of the remaining testis, whereas concomitant treatment of these animals with ovine FSH reversed the inhibitory effects of FF. Serum inhibin concentrations were determined using two radioimmunoassay (RIA) systems; one assay utilized an antiserum generated against intact bovine inhibin and the other was directed against an alpha-inhibin fragment. Both assays showed a decline in inhibin levels following hemicastration. In addition, increases in serum inhibin concentrations were observed following FF administration in both RIAs; however, the relative increase in inhibin over levels in hemicastrated rats was greater using the intact inhibin assay. In summary, these data suggest that the increase in FSH concentrations after hemicastration is related to a reduction in inhibin levels, and that this FSH rise is a primary signal for initiating compensatory testicular hypertrophy in prepubertal rats. Furthermore, exogenous FSH administration overcame the inhibitory effects of FF on the testes, suggesting that inhibin may not act directly at the gonadal level.

Serum Bioactive Follicle-Stimulating Hormone-Like Activity Increases during pregnancy

It is presently accepted that high circulating steroid levels during pregnancy suppress pituitary immunoreactive FSH (I-FSH) secretion from early pregnancy to term. In this study we tested the hypothesis that bioactive FSH (B-FSH) in the sera of pregnant women would likewise be suppressed. Serum samples were obtained from one woman daily for 21 days after the I-LH surge, and in a second, every 10 min for 10 h on days 10, 20, and 27 after the I-LH surge. Single serum samples were also obtained from women at 2–41 weeks of gestation. In all samples, I-LH/hCG, I-FSH, B-FSH, progesterone (P), and estradiol (E2) were measured. In the first woman, serum I-FSH levels were suppressed from days 9–21 after the LH surge (0.2 ± 0.04 ng/mL; 1.9 ± 0.3 IU/ L), whereas serum B-FSH increased linearly from 1.7 ng/mL (5.3 1U/L) on day 9 post-I-LH surge to 6.0 ng/mL (18.6 IU/L) on day 17 (r = 0.91; P < 0.01) and remained elevated through day 21. In the second woman, the mean ± SE of the serum IFSH concentrations were 0.7 ± 0....

Determination of bioactive FSH in rhesus monkeys (Macaca mulatta).

AbstractStudies of the reproductive biology of nonhuman primates are commonly hindered by the lack of homologous, sensitive immunoassay systems for gonadotropins. The recent development of a bioassay based upon folliclestimulating hormone (FSH)‐stimulated estradiol production by rat Sertoli cells (Padmanabhan et al.: Endocrinology 121:1089–1098, 1987) offers a novel opportunity to expand our knowledge of the physiological importance and regulation of this important reproductive hormone in these species. Accordingly, we have established the utility of the rat Sertoli cell FSH bioassay to study the reproductive biology of rhesus monkeys. Analysis of medium from cultured rhesus monkey pituitary cells demonstrates the ability of this assay system to specifically and sensitively detect macaque FSH. Serial dilutions of unextracted urinary samples stimulate estradiol in parallel with the reference standard. The pattern of bioactive FSH in daily urine samples throughout the menstrual cycle resembles that normally observed in serum, displaying a clear preov alatory gonadotropin surge. In attempts to analyze rhesus monkey serum, severe interference with cellular estradiol production was found with extremely low serum sample volumes. In order to circumvent this problem, a serum extraction procedure utilizing metaphosphoric acid was developed which permits the accurate determination of bioactive FSH in serum. The pattern of serum bioactive FSH secretion throughout the menstrual cycle is in general agreement with that observed by FSH RIA, although immunoreactive FSH values are consistently higher. The ability to detect bioactive FSH in macaques will significantly enhance our research capabilities with nonhuman primate species which share many physiological similarities with man. Important applications also may be found in studies on the reproductive biology in endangered species of primates.

Serum Bioactive Follicle-Stimulating Hormone-Like Activity Increases during Pregnancy*

It is presently accepted that high circulating steroid levels during pregnancy suppress pituitary immunoreactive FSH (I-FSH) secretion from early pregnancy to term. In this study we tested the hypothesis that bioactive FSH (B-FSH) in the sera of pregnant women would likewise be suppressed. Serum samples were obtained from one woman daily for 21 days after the I-LH surge, and in a second, every 10 min for 10 h on days 10, 20, and 27 after the I-LH surge. Single serum samples were also obtained from women at 2-41 weeks of gestation. In all samples, I-LH/hCG, I-FSH, B-FSH, progesterone (P), and estradiol (E2) were measured. In the first woman, serum I-FSH levels were suppressed from days 9-21 after the LH surge (0.2 +/- 0.04 ng/mL; 1.9 +/- 0.3 IU/L), whereas serum B-FSH increased linearly from 1.7 ng/mL (5.3 IU/L) on day 9 post-I-LH surge to 6.0 ng/mL (18.6 IU/L) on day 17 (r = 0.91; P less than 0.01) and remained elevated through day 21. In the second woman, the mean +/- SE of the serum I-FSH concentrations were 0.7 +/- 0.04, 0.1 +/- 0.01, and 0.1 +/- 0.01 ng/mL (5.5 +/- 0.3, 0.9 +/- 0.1, 1.1 +/- 0.1 IU/L) on days 10, 20, and 27 post-I-LH surge, respectively. The mean serum B-FSH concentrations increased from 3.1 +/- 0.2 ng/mL (9.6 +/- 0.7 IU/L) on day 10 to 7.5 +/- 0.6 ng/mL (23.2 +/- 1.7 IU/L) on day 27. Using the DETECT pulse analysis method at the 0.01 confidence level, the serum I-FSH pattern was relatively nonpulsate, while serum B-FSH averaged 8, 7, and 10 pulses/10 h on post-LH surge days 10, 20, and 27. Incremental peak amplitudes were 3.5 +/- 0.7, 4.6 +/- 0.4, and 8.0 +/- 1.3 ng/mL (10.9 +/- 2.2, 14.3 +/- 1.2, and 24.8 +/- 4.0 IU/L), respectively. In the cross-sectional study, serum I-FSH levels remained low, while serum B-FSH concentrations increased from 4.2 +/- 0.8 ng/mL (13.2 +/- 2.5 IU/L) during the early first trimester to 59.3 +/- 2.9 ng/mL (183.8 +/- 9.0 IU/L) by the late third trimester. There was no correlation between serum B-FSH and hCG levels. Incubates of term placentae secreted B-FSH in preference to I-FSH (i.e. B-FSH, 33.0 +/- 9.6 ng/h/g placental tissue; I-FSH, 0.7 +/- 0.1 ng/h/g).(ABSTRACT TRUNCATED AT 400 WORDS)

Serum FSH bioactivity in pregnant women is not due to FSH

Journal Article Serum FSH bioactivity in pregnant women is not due to FSH Get access M Simoni, M Simoni Max-Planck-Gesellschaft, Klinische Forschungsgruppefür Reproduktionsmedizin und Institut für Reproduktionsmedizin, Westf. Wilhelms- Universität, Münster Search for other works by this author on: Oxford Academic Google Scholar S Khan, S Khan Max-Planck-Gesellschaft, Klinische Forschungsgruppefür Reproduktionsmedizin und Institut für Reproduktionsmedizin, Westf. Wilhelms- Universität, Münster Search for other works by this author on: Oxford Academic Google Scholar Ch De Geyter, Ch De Geyter Max-Planck-Gesellschaft, Klinische Forschungsgruppefür Reproduktionsmedizin und Institut für Reproduktionsmedizin, Westf. Wilhelms- Universität, Münster Search for other works by this author on: Oxford Academic Google Scholar E Nieschlag E Nieschlag Max-Planck-Gesellschaft, Klinische Forschungsgruppefür Reproduktionsmedizin und Institut für Reproduktionsmedizin, Westf. Wilhelms- Universität, Münster Search for other works by this author on: Oxford Academic Google Scholar Acta Endocrinologica (Norway), Volume 120, Issue 3_Supplement, Jun 1989, Page S68, https://doi.org/10.1530/acta.0.120S068 Published: 01 June 1989

Bioactive follicle-stimulating hormone responses to intravenous gonadotropin-releasing hormone in boys with idiopathic hypogonadotropic hypogonadism.

To test the hypothesis that exogenous pulsatile administration of GnRH will increase serum bioactive FSH (bFSH) levels, we studied four boys with suspected idiopathic hypogonadotropic hypogonadism (IHH). These boys presumably secreted relatively little GnRH. By virtue of their low baseline serum gonadotropin levels yet responsive pituitary gonadotrophs, these boys with IHH proved to be an excellent clinical model to test this hypothesis. Administration of GnRH (0.025 microgram/kg.dose) iv at 1- or 2-h intervals for 3-5 days resulted in an increase in serum bFSH after 91% of the GnRH doses. Serum immunoreactive FSH (iFSH) and LH (iLH) levels increased after 42% and 64% of the GnRH doses, respectively. Ninety percent of the iLH responses were concordant with bFSH responses, but only 33% of the iLH responses were concordant with iFSH responses. The serum bFSH responses occurred consistently within 20 min after GnRH administration and resulted in an increased serum bioactive to immunoreactive FSH ratio. By 60 min, serum bFSH levels had returned to preinjection levels. Serum testosterone and estradiol levels did not change during the period of GnRH administration in three of the four boys. We conclude that pulsatile, low dose iv GnRH administration in boys with IHH elicits significant serum bFSH increases by 20 min; the newly secreted FSH is preferentially enriched with increased in vitro FSH bioactivity, and it is rapidly cleared from serum (60 min). Therefore, serum bFSH measurements may provide a sensitive index of GnRH effects on the gonadotrophs.

Modulation of serum follicle-stimulating hormone bioactivity and isoform distribution by estrogenic steroids in normal women and in gonadal dysgenesis.

To determine the influence of estrogenic steroids on serum FSH bioactivity (B) and immunoreactivity (I) and the FSH isoform distribution profiles, we studied normal women during ovulatory menstrual cycles and a patient with gonadal dysgenesis treated with diethylstilbestrol (DES). Four women with ovulatory menstrual cycles, as judged from their serum immunoreactive LH, FSH, progesterone, and estradiol profiles in daily blood samples, had a significant increase in the mean FSH B/I ratio (P less than 0.05) during the midcycle phase of their menstrual cycles. Similarly, in the patient with gonadal dysgenesis the FSH B/I ratio rose significantly (P less than 0.05) after 3 weeks of DES treatment and declined during the posttreatment period. In five additional normal women, serum obtained during the follicular, midcycle, and luteal phases of their menstrual cycles was chromatofocused, and the FSH isoform distribution pattern determined. Sera obtained from the patient with gonadal dysgenesis before, during, and after DES administration were pooled and studied similarly. Chromatofocusing of a human pituitary tumor extract allowed for determination of the FSH B/I ratio in different pH ranges. The highest FSH B/I ratio was found in the more basic fractions (pH range 5.6-6.0) compared to the acidic fractions. During both the midcycle phase of the normal cycles and the DES administration period in the studies of the patient with gonadal dysgenesis, there was a shift of the FSH isoforms (as measured by immunoassay) to the basic pH range. In contrast, the mid- to late luteal phase samples, which had low B/I ratios, had an increase in FSH isoforms in the acidic pH range (less than 4.8). Similarly, in the patient with gonadal dysgenesis FSH isoforms in the basic range were more abundant during the DES treatment period than in the pre- or posttreatment serum pools. Therefore, it appears that endogenous and exogenous estrogenic stimulation alters FSH isoform distribution such that FSH isoforms that are more basic and have increased biological activity are secreted.

Maintenance of the ratio of bioactive to immunoreactive follicle-stimulating hormone in normal men during chronic luteinizing hormone-releasing hormone agonist administration.

Chronic administration of LHRH agonist analogs to humans reduces gonadal function through pituitary desensitization. Serum immunoreactive gonadotropin levels are modestly reduced, whereas serum bioactive LH levels are drastically suppressed. The effects on bioactive FSH levels, however, are not known. In this study, serum bioactive FSH was measured using an in vitro granulosa cell aromatase bioassay in four normal men given a LHRH agonist, [D-Trp6,Pro9-NEt]LHRH (LHRHA; 500 micrograms/day for 16 weeks), by sc infusion and testosterone enanthate (TE; 100 mg, im every 2 weeks) and in five men given 500 micrograms/day LHRHA by daily sc injection for 20 weeks and TE (100 mg every 2 weeks) from weeks 10 through 20. During the first study, serum immunoreactive FSH levels (IR-FSH) decreased by 56.5 +/- 4.8% (+/- SEM), and serum bioactive FSH (Bio-FSH) level decreased by 57.6 +/- 6.4%. The ratio of Bio-FSH to IR-FSH did not change. During the second study, both serum IR-FSH and Bio-FSH levels followed a triphasic pattern, decreasing slightly but not significantly immediately after initiation of LHRHA administration, progressively increasing to a peak (P less than 0.5 vs, baseline) at week 10, and then, after addition of TE to this regimen, decreasing slightly again. The Bio-FSH to IR-FSH ratio, as in the first study, did not change. When serum obtained at week 10 during the second study, just before initiation of TE, was chromatographed on a Sephadex G-100 column, IR-LH eluted in two distinct peaks, while IR-FSH eluted as a single peak. These results demonstrate that in normal men chronic LHRHA administration alone for up to 10 weeks or LHRHA plus TE for up to 16 weeks does not alter the qualitative characteristics of secreted FSH, since there was no dissociation between serum IR- and Bio-FSH levels.

Serum bioactive and immunoreactive follicle-stimulating hormone in prostatic cancer patients during gonadotropin-releasing hormone agonist treatment and after orchidectomy.

Serum bioactive and immunoreactive FSH levels were measured in five prostatic cancer patients during treatment for 6 months with the GnRH agonist analog buserelin (Hoechst; 600 micrograms, intranasally, 3 times per day) and for up to 12 weeks after subsequent orchidectomy. FSH bioactivity was measured using a sensitive specific in vitro granulosa cells aromatase bioassay. Before buserelin treatment, mean serum FSH bioactivity and immunoreactivity were 19.7 +/- 4.1 (+/- SE) IU/L (n = 5) and 13.7 +/- 3.8 IU/L, respectively, with a bioactivity to immunoactivity (B/I) ratio of 1.7 +/- 0.2. After the initiation of treatment with the GnRH agonist, FSH bio- and immunoactivities both transiently increased for 1-3 days. The increase in bioactivity was greater and prolonged, and the B/I ratio increased nearly 7-fold in 2 weeks. Serum FSH immunoreactivity declined to below the pretreatment level in 5 days and remained low for the rest of the treatment period. In contrast, serum FSH bioactivity did not decrease significantly below the pretreatment level during the 6-month treatment period, although the B/I ratio returned slowly toward the pretreatment value. After orchidectomy, both FSH activities increased dramatically, and the B/I ratio rose transiently from 1.5 to 7 in 2 weeks. Interestingly, serum FSH bioactivity and immunoreactivity decreased significantly (P less than 0.05) 1 day after orchidectomy in the buserelin-treated patients. In contrast, serum FSH immunoreactivity increased during the same period (P less than 0.05) in patients treated only by orchidectomy (FSH bioactivity was not measured). In conclusion, serum FSH bioactivity increases acutely more than FSH immunoreactivity after initiation of GnRH agonist treatment or orchidectomy. In the former case, serum FSH bioactivity subsequently returned to the pretreatment range. A clear decline during long term agonist treatment occurred only in serum FSH immunoreactivity, in contrast to the concomitant decline in serum LH bio- and immunoreactivities reported previously. The persistence of bioactive FSH may explain the inconsistent effects of GnRH agonist treatment on the suppression of spermatogenesis. The acute decrease in serum FSH after orchidectomy in the buserelin-treated men suggests that the testes may produce a factor that stimulates pituitary FSH secretion.

Serum bioactive follicle-stimulating hormone in men with idiopathic azoospermia and oligospermia.

Using an in vitro granulosa cell aromatase bioassay (GAB), serum bioactive FSH (bio-FSH) levels were measured in 20 fertile men and 74 men with idiopathic azoospermia or oligospermia. The serum bio-FSH levels measured by the GAB assay and the immunoreactive FSH (immuno-FSH) levels measured by RIA were positively correlated (r = 0.93). Compared to normal men, serum bio-FSH and immuno-FSH levels were elevated in patients with idiopathic azoospermia associated with severe germinal epithelium damage; the bioactive to immunoreactive ratio (B:I ratio) of FSH in these men [mean, 1.5 +/- 0.5 (+/- SD)] was significantly lower than that in fertile men (2.7 +/- 0.8). Similarly, in men with moderate and severe oligospermia, the B:I ratios of FSH were decreased (1.4 +/- 0.4 and 1.7 +/- 0.3, respectively). Although serum immuno-FSH levels correlated weakly with mean sperm concentrations in the normal and oligospermic men (r = -0.35), no relationship was found between serum bio-FSH and sperm concentrations. The B:I ratio of FSH correlated weakly with sperm concentration (r = 0.46). These findings suggest that the B:I ratio of FSH measured by the GAB assay decreases in patients with low sperm concentrations and germinal cell failure.