Serum bioactive follicle-stimulating hormone-like activity in human pregnancy is a methodological artifact

Serum from pregnant women has been shown to contain both FSH-like and FSH antagonistic activities when measured by an in vitro bioassay based upon FSH-dependent aromatase activity of immature rat Sertoli cells. In the present study we further tested the hypothesis that the FSH-like bioactivity of pregnancy serum was due to an authentic aromatase stimulator. A potent inhibitor of aromatase which completely blocked the FSH action on Sertoli cells had no effect on the bioactivity of pregnancy serum. Experiments using conversion of tritiated testosterone to estradiol showed that the factor did not stimulate aromatase activity in rat Sertoli cells. After incubation with pregnancy serum, equally high amounts of estradiol were measurable in the medium in both the absence and presence of Sertoli cells. The activity was almost completely lost after charcoal treatment or ether extraction of the serum and was shown to probably be due to the release of endogenous estrogens by the carrier proteins in the incubation medium of the Sertoli cell assay. These data suggest that the FSH-like bioactivity in serum from pregnant women is an artifact due to nonspecific interference(s) in the bioassay.     

Human adipogenic serum activity increases during pregnancy

Adipogenic factor required for adipose differentiation of 3T3-F442A cells is present in human serum. Its activity increases significantly 3-4 fold in maternal serum after the 25th-28th weeks of pregnancy. It remains high until parturition and it is also found at high levels in serum from umbilical cord blood, whereas amniotic fluid from late gestation ages has a very low adipogenic activity. Adipogenic activity from maternal serum decreases abruptly one day after parturition and it reaches normal levels similar to those found in non-pregnant women, remaining constant thereafter. It is suggested that adipogenic serum activity could have some significance for human adipose tissue differentiation.     

Serum bioactive follicle-stimulating hormone levels in girls with precocious sexual development

We studied the serum immunoreactive (immuno) and bioactive (bio) FSH concentrations in 16 prepubertal children (1.3-9 yr old), 6 girls with premature thelarche (0.8-2 yr old), and 9 girls with central precocious puberty (2.5-9.3 yr old). The serum bio-FSH was measured by the granulosa cell aromatase bioassay. The basal serum bio-FSH levels were not significantly different in patients with central precocious puberty (6.4 +/- 1.5 IU/L), premature thelarche (7.5 +/- 0.5 IU/L), and prepubertal controls (4.4 +/- 0.7 IU/L). However, the peak responses of both serum immuno- and bio-FSH levels to iv GnRH were higher in patients with premature thelarche (immuno-FSH, 29.3 +/- 2.3 IU/L; bio-FSH, 100.7 +/- 12.2 IU/L) than in those with central precocious puberty [immuno-FSH, 17.5 +/- 3.1 IU/L (p less than 0.05); bio-FSH, 42.4 +/- 9.8 IU/L (p less than 0.01)]. This suggests that in children with premature thelarche, there is a predominant immuno- as well as bio-FSH response to GnRH. After 12 months of GnRH agonist therapy, both serum immuno- and bio-FSH levels were suppressed in patients with central precocious puberty. The differences in clinical presentation between central precocious puberty and premature thelarche cannot be explained by the differences in FSH bioactivity.     

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.     

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 concentrations from prepuberty to adulthood: a cross-sectional study

Serum bioactive (B) LH concentrations increase with each pubertal stage and exceed immunoreactive (I) measurements in boys and girls throughout puberty. These results have been attributed to increased GnRH secretion and/or sex steroid modulation. FSH secretion is likewise affected by these factors. We, therefore, tested the hypothesis that serum B-FSH concentrations would increase with each stage of puberty in boys and girls. In this study we compared the serum concentrations of B-FSH, I-FSH, and sex steroids and stages of puberty (determined according to Tanner) in 111 sera obtained from boys and girls from 6-18 yr of age with the results obtained from 6 young men under the age of 35 yr and 13 cycling women (studied during the follicular, periovulatory, and luteal phases of their menstrual cycles). The serum I-FSH, testosterone (T), and estradiol (E2) concentrations were determined by RIAs, and B-FSH was determined by the rat Sertoli cell aromatase induction assay. The results were analyzed by one-way analysis of variance followed by Scheffe's test for each gender and two-way analysis of variance followed by Student-Newman-Keuls test for comparison of the results between sexes. In boys the mean serum T concentrations increased progressively with each stage of pubertal development up to Tanner stage 4 (P less than 0.01). The mean serum I-FSH concentration at Tanner stage 1 was 0.7 +/- 0.1 ng/mL (hFSH-3) and did not change significantly until Tanner stage 4, when it was increased to 3.7 +/- 1.0 ng/mL (P less than 0.05). The mean serum I-FSH concentrations for Tanner stage 5 and adult men were not statistically different, but were lower than in Tanner stage 4. Mean serum B-FSH concentrations measured with the same standard were 1.9 +/- 0.4, 3.1 +/- 0.4, 2.7 +/- 0.4, 4.2 +/- 1.4, and 3.6 +/- 0.3 ng/mL in Tanner stages 1-5, respectively. These were not significantly different. In girls the mean serum E2 concentrations increased progressively between the Tanner stages (P less than 0.00005, by two-way analysis of variance). Mean serum I-FSH levels did not change significantly with the achievement of different pubertal stages. The mean B-FSH concentrations were 2.7 +/- 0.4, 2.8 +/- 0.5, 3.8 +/- 0.8, 2.8 +/- 0.7, and 3.9 +/- 0.6 ng/mL at Tanner stages 1-5, respectively, and were, likewise, not statistically significantly different. In adult women the mean serum B-FSH concentrations during the follicular phase of the menstrual cycle were not significantly different from pubertal values.(ABSTRACT TRUNCATED AT 400 WORDS)     

Circulating bioactive inhibin levels during human pregnancy

In this study bioactive inhibin was measured in 112 serum samples from 103 pregnant women by a sensitive ovine pituitary cell culture system. Human inhibin activities were detected in a range between 0.02-5.28 U/mL at six dilutions by using serum from the 38-week pregnant women as a quality control. A remarkable increase in serum inhibin was observed from 4 to 38 weeks of pregnancy. The mean serum inhibin level was 1.58 U/mL at 4 weeks. Thereafter, inhibin levels increased progressively with the weeks of pregnancy (r = 0.988; P less than 0.001). In the midterm of pregnancy, serum inhibin was elevated at average levels of 2.84 and 3.84 U/mL at 20 and 28 weeks, respectively. The peak level of inhibin (5.33 U/mL) was obtained at 38 weeks, which was an increase of 237% compared to that at 4 weeks. The average rate of increase in serum inhibin levels was 14.51% every 2-4 weeks (ranging from 8.1-20%). These findings suggest that circulating inhibin is useful marker during human pregnancy.     

Serum melatonin during human pregnancy

Serum melatonin concentrations from 55 pregnant healthy women (13 during the first, 18 during the second and 24 during the third trimester) and 11 non-pregnant control women were measured radioimmunologically at 11.00 h (Study A). In addition, serum melatonin concentrations from 12 women in early and 11 women in late pregnancy were measured every four hours throughout the day (Study B). Serum melatonin levels during the third trimester of pregnancy (76.5 +/- 38.3 pmol/l) were significantly (p less than 0.01) higher than those during the first (29.7 +/- 9.9 pmol/l) and the second trimester (39.1 +/- 11.2 pmol/l) and those of non-pregnant control women (41.7 +/- 15.5 pmol/l) and there was a positive correlation between the week of gestation and serum melatonin at 11.00 h (Study A). A clear diurnal rhythm in serum melatonin concentrations was found both in early and in late pregnancy (Study B). The amplitude and duration of the nocturnal rise of melatonin were higher during late pregnancy, but there was no clear phase shift. Increased serum concentration of melatonin in late pregnancy may be due to increased synthesis and secretion or retarded metabolism of melatonin during late pregnancy.     

Circulating bioactive follicle-stimulating hormone and less acidic follicle-stimulating hormone isoforms increase during experimental induction of puberty in the female lamb.

The pubertal process with its multifaceted neuroendocrine control provides an excellent model for the study of the regulation of FSH heterogeneity. We tested the hypothesis that during the pubertal transition in the female lamb 1) an increase in both pituitary and circulating bioactive FSH concentrations occur and 2) that the increase in bioactivity is associated with a change in the distribution pattern of both pituitary and circulating FSH isoforms. Pituitary and serum immunoreactive (I), and bioactive (B, Sertoli cell bioassay) FSH concentrations were measured in six prepubertal lambs (18 +/- 1 weeks, 29.9 +/- 2.8 kg body weight; mean +/- SE) and compared to those of six others (24.2 +/- 2.2 weeks of age, 41.4 +/- 2.5 kg body weight) during the pubertal transition period. Puberty was synchronized by pulsatile iv administration of GnRH (2 ng/kg every 2 h for 24 h and then at hourly intervals for the next 12 h) in a manner mimicking the I-LH pulse patterns observed during the natural transition to adulthood. Blood samples were collected at 12-min intervals for 4 h from both groups of lambs; for the pubertal group this included the final 32-36 h of GnRH administration. At the end of the study, a 25 ml volume of peripheral blood was collected from both prepubertal and pubertal females for the determination of serum FSH distribution patterns; the lambs were then euthanised, and pituitaries were removed for determination of pituitary hormone content and FSH isoform distribution patterns. In addition, the distribution pattern of I-FSH isoforms in the pituitary and serum from both groups of lambs were compared. The pubertal stages of all lambs were verified by measuring the size of follicles, the circulating concentrations of estradiol (E2) and inhibin, and the I-LH pulse patterns. Prepubertal lambs had low frequency I-LH pulses, small (2-3 mm) size ovarian follicles and low circulating concentrations of E2 (4.1 +/- 0.4 pg/ml) and inhibin (38.0 +/- 2.9 U/ml WHO). By contrast, all the pubertal lambs had hourly I-LH pulse frequency (induced with exogenous GnRH), a large (5-6 mm) follicle (in one lamb a 4-mm follicle), follicular phase levels of E2 (7.1 +/- 0.8 pg/ml), and higher concentrations of inhibin (53.2 +/- 3.1 U/ml).(ABSTRACT TRUNCATED AT 400 WORDS)     

Serum bioactive follicle-stimulating hormone during the human menstrual cycle and in hyper- and hypogonadotropic states: application of a sensitive granulosa cell aromatase bioassay

A sensitive in vitro assay based on the stimulation of estrogen production by cultured rat granulosa cells was recently developed for the measurement of biologically active FSH. This bioassay system is specific for FSH, highly sensitive, and capable of measuring basal FSH levels in rat serum. The granulosa cell aromatase bioassay was improved by the use of additives known to enhance FSH activity and by pretreatment of serum with 12% polyethylene glycol to remove inhibitory substances. We applied this method to the measurement of bioactive FSH levels in serum samples from human subjects. As determined in daily blood samples during ovulatory menstrual cycles in seven women, bioactive FSH levels exhibited a pattern closely resembling that of immunoreactive FSH. The mean bioactive serum FSH levels were 29.9, 20.5, 39.2, and 14.8 mIU/ml for the early follicular phase, late follicular phase, preovulatory surge, and luteal phase, respectively. The bio- to immunoratio (B:I) throughout the menstrual cycle ranged from 1.4-3.4, with a mean of 2.5. The ratios for early follicular phase, late follicular phase, preovulatory surge, and luteal phase were 2.7, 2.3, 1.4, and 2.6, respectively. The correlation coefficient (r) of the serum FSH values obtained by bioassay and RIA was 0.91. FSH bioactivity was also measured in patients in each of the following categories with the following mean values: oral contraceptive pill users (undetectable), hypothalamic amenorrhea (18.7 mIU/ml; B:I, 2.6), premature ovarian failure (163 mIU/ml; B:I, 1.7), and postmenopausal women (191 mIU/ml; B:I, 1.6). These findings suggest that measurement of immunoreactive FSH levels correctly reflects the biological activity of FSH in serum of cycling women and patients in certain hyper- and hypogonadotropic states. The granulosa cell aromatase bioassay represents a new tool for future assessments of biologically active FSH in physiological and pathophysiological conditions.     

Serum bioactive and immunoreactive follicle-stimulating hormone levels and the response to clomiphene in healthy young and elderly men

Testicular function declines with normal aging, while serum immunoreactive LH and FSH levels increase. Since there are reports of an age-related decrease in the ratio of bioactivity to immunoreactivity (B/I ratio) for LH, we used a newly available bioassay for FSH to assess age-associated changes in the bioactivity and B/I ratio of FSH in man. Thirty-nine healthy men (23 young and 16 elderly) had single blood samples drawn. In addition, a subset of these men (12 young and 13 elderly) underwent frequent blood sampling for 24 h, both before and after 7 days of clomiphene citrate (CC) administration. Hourly blood samples from the 24-h sampling were pooled, and these, along with the single samples, were assayed for FSH by an in vitro bioassay system, using estrogen production by immature rat granulosa cells as the end point, and by RIA. Baseline single sample mean FSH, as measured by bioassay, was similar in young and elderly men [386 +/- 98 (+/- SEM) and 342 +/- 77 ng/mL, respectively]. Baseline mean FSH, measured by RIA, was significantly higher (P less than 0.001) in elderly men (234 +/- 31 ng/mL) than in young men (122 +/- 12 ng/mL). The baseline FSH B/I ratio based on single sampling was significantly lower (P less than 0.01) in elderly men (1.4 +/- 0.2) than in young men (2.7 +/- 0.3). In the men given CC and sampled for 24 h, mean bioactive FSH levels increased significantly in both the young (1180 +/- 282 ng/mL) and the elderly (992 +/- 227 ng/mL; P less than 0.01 for both values compared to baseline). Mean FSH by RIA also increased to similar levels in these young (217 +/- 34 ng/mL) and elderly (258 +/- 45 ng/mL) men. The FSH B/I ratio was 4.8 +/- 0.8 in young and 4.7 +/- 1.1 in elderly men after CC administration. We conclude that serum bioactive FSH levels are similar in elderly and young men, suggesting that the age-related decline in testicular function in man cannot be explained by a chronic deficiency in FSH stimulation; elderly men have a lower serum FSH B/I ratio than young men, which may reflect changes in the circulating form of FSH with aging; and administration of CC to young and elderly men increases both bioactive and immunoreactive serum FSH, implying preserved hypothalamic-pituitary responsiveness in the elderly.     

Urinary follicle-stimulating hormone during pregnancy: relationship to sex of fetus.

FSH excretion was determined by RIA in 111 urine samples from 23 pregnant women. The use of acetone extraction allowed a 20-fold concentration of urine and the accurate quantitation of hormone levels. Between 10 weeks of gestation and term, FSH secretion was consistently low, with a mean excretion of 18 mIU/h; this amount compares to levels found in other states of marked hCG excess (e.g. choriocarcinoma) and is considerably less than the FSH excretion by prepubertal children. Maternal levels of urinary FSH did not differ with sex, suggesting a primary maternal pituitary origin for pregnancy FSH.     

Serum total IgE level during pregnancy and postpartum

BackgroundStudies on serum IgE levels during pregnancy are limited.ObjectiveTo investigate the course of serum total IgE levels during pregnancy and postpartum.Methods159 pregnant subjects provided 218 serum samples during various stages of pregnancy and the postpartum period. Serum total IgE geometric means were compared at various trimesters and postpartum. In addition, the postpartum IgE data were analysed according to the method of delivery. Analysis was also done according to history of allergy.ResultsThe geometric mean serum total IgE was 20.5 IU/ml in the first trimester, 20.8 IU/ml in the second and 22.2 IU/ml in the third. Postpartum serum IgE level showed a lower mean, 14.9 IU/ml during the early postpartum period (less than 30 days) compared to 30.3 IU/ml during the late postpartum period (30 days-25 weeks). However this was not statistically significant. Serum IgE in the postpartum period also did not differ according to method of delivery. A history of allergy was positive in 98 samples, negative in 61 and unclear in 59. Using analysis of variance, none of these three groups showed significant change in serum total IgE level during pregnancy or postpartum.ConclusionIn this cross-sectional study, serum total IgE levels showed no statistically significant changes during pregnancy or postpartum. This finding would be of greater weight if reproduced in a larger number of subjects with multiple serial samples at fixed regular time intervals during pregnancy and postpartum.     

Cardiac sympathetic activity during rat pregnancy

The turnover of injected tracer [3H] norepinephrine (NE) was determined in heart and interscapular brown adipose tissue of virgin and 10-day and 20-day pregnant rats. In two experiments fractional [3H]NE turnover in heart was 87% and 92% higher in 20-day pregnant animals compared to virgin controls, but did not differ between 10-day pregnant and control animals. NE turnover in brown adipose tissue did not differ between control and pregnant animals at either gestational age. Twenty-four-hour urinary excretion of NE, epinephrine (E), and dopamine (D) was measured serially in six pregnant rats and compared to virgin controls. NE excretion during pregnancy was significantly higher than the controls and showed a progressive increase during the last third of pregnancy. At term the excretion rate was 2.6-fold greater than that of controls. Excretion of E and D did not differ between pregnant and nonpregnant animals. It is concluded that cardiac sympathetic nervous system activity increases during rat pregnancy. That this change in sympathetic activity is not global is indicated by the finding of unchanged NE turnover in interscapular brown adipose tissue. Urinary excretion data are consistent with increased sympathetic activity during late gestation, with no change in adrenal medullary function.