Relative roles of inhibin B and sex steroids in the negative feedback regulation of follicle-stimulating hormone in men across the full spectrum of seminiferous epithelium function

Effect of Combined Low Dose Human Gonadotropic Hormone, Follicle Stimulating Hormone, and Testosterone Therapy (LFT Regimen) Versus Conventional High Dose Human Gonadotropic Hormone and Follicle Stimulating Hormone on Spermatogenesis and Biomarkers in Men With Hypogonadotropic Hypogonadism

OBJECTIVE

In male congenital hypogonadotropic hypogonadism (CHH), it was observed that lower dose human gonadotropic hormone (hCG) can maintain normal intratesticular testosterone levels. We propose this study to compare the low-dose hCG, follicle stimulating hormone (FSH), and Testosterone (T) [LFT Regimen] to conventional treatment to induce virilization and fertility.

DESIGN

This open-label randomized pilot study was conducted from June 2020 to December 2021.

SUBJECTS AND OUTCOME MEASURES

CHH were randomly assigned to either the LFT regimen (Group A)-low-dose hCG (500U thrice per week), FSH (150U thrice per week), and T(100 mg biweekly) or conventional therapy(GroupB) with high hCG dose(2000U thrice per week) and the same FSH dose. The hCG dosage was titrated to reduce anti-mullerian hormone (AMH) by 50% and normalization of plasma T in groups A and B, respectively. The primary objective was to compare the percentage of individuals who achieved spermatogenesis between the two groups.

RESULTS

Out of 30 patients, 23 (76·7%) subjects achieved spermatogenesis, and the median time was 12 (9-14·9) months. There was no difference in achieving spermatogenesis between the two groups (64·3% vs 7·5%,P = 0·204), and even the median time for spermatogenesis was similar (15months vs 12months,P = 0·248). Both groups had nonsignificant median plasma AMH at spermatogenesis, [6·6 ng/ml (3·3-9·76) vs4·41 ng/ml (2·3-6·47), P = 0·298]. Similarly, the median plasma Inhibin B at spermatogenesis between groups were comparable [152·4 pg/ml (101·7-198·0) vs49·1 pg/ml (128·7-237·3), P = 0·488].

CONCLUSIONS

A reasonable approach to induce fertility in male CHH is to initiate combination therapy using FSH, low-dose hCG targeting AMH <6·9 ng/ml, along with T to achieve normal range. Monitoring AMH could serve as a proxy indicator of spermatogenesis.

Follicle-stimulating hormone treatment for male factor infertility

Follicle-stimulating hormone (FSH) treatment has been proven effective in stimulating spermatogenesis and improving the reproductive ability of men with hypogonadotropic hypogonadism, while the usefulness of such a treatment in infertile patients with normal pituitary function is restricted to a subgroup of responders that, however, cannot be identified by the current diagnostic tools before treatment. In this review we summarize the role played by FSH in the modulation of spermatogenesis, the effect of FSH treatment at a standard replacement dose and at higher dose on sperm parameters, spontaneous and in vitro fertilization pregnancy rates, and the efforts made to identify possible responders to FSH treatment.

Occupational use of agrochemicals results in inhibited cholinesterase activity and altered reproductive hormone levels in male farmers from Buea, Cameroon

The efficiency of agro pesticides and fertilizers in eliminating pests and scaling up crop yield has motivated farmers to increase their use. Unfortunately, health hazards caused on farmers by these agrochemicals are of growing concern, though not well elucidated. In order to evaluate the effects of occupational exposure to agrochemicals on some key parameters of male farmers' health in Buea Subdivision, Cameroon, a total of 101 men, including 62 farmers using the agrochemicals and a reference population of 39 men not involved in occupational utilization of the agrochemicals, were interviewed on use of protective equipment, exposure symptoms and reproductive health status. Thereafter, serum cholinesterase [acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE)] activities, total antioxidant capacity and reproductive hormones [follicle-stimulating hormone (FSH), luteinizing hormone and testosterone] were assessed. Results revealed that farmers mainly used insecticides followed by fungicides, herbicides and fertilizers, but with inadequate protective measures. The use of agrochemicals resulted in several exposure symptoms including weakness, itches, burning sensation, headache, sneezing, coughing and vomiting, as well as decrease in serum AChE activity when compared to the reference population. The agrochemicals impacted negatively on the farmers' reproductive health as evidenced by increased FSH levels. Taken altogether, these results suggested that exposure to agrochemicals adversely affects farmers' health. Therefore, there is a need to further sensitize the farmers on the use of protective equipment to mitigate the exposure and resulting health hazards.

Testicular torsion: its effect on autoimmunisation, pituitary-testis axis and correlation with primary gonadal dysfunction in boys

BACKGROUND

Torsion of the testis is an urgent surgical condition that endangers the viability of the gonad and the fertility of the patient. Our aim was to assess potential autoimmune processes and hormonal abnormalities in boys operated on due to that illness.

METHODS

The authors evaluated the levels of antibodies against sperm and Leydig cells, concentrations of follicle-stimulating, luteinizing and anti-Müllerian hormone, testosterone, oestradiol and vascular endothelial growth factor in the serum in 28 boys operated on due to torsion of the testis. Patients' sexual maturity was assessed according the Tanner scale (group G1, G4 and G5).

RESULTS

No antibodies against sperm or Leydig cells were found in the serum. Statistically significant differences in follicle-stimulating and anti-Müllerian hormone concentrations were observed in the G1, and they were higher in the study than in the control group. There were no statistically significant differences in luteinizing hormone, testosterone, oestradiol and vascular endothelial growth factor concentrations in the study group or control group. Testosterone concentration was unrelated to total testicular volume.

CONCLUSIONS

Results did not confirm the autoimmune process in boys with torsion of the testis. The pituitary-testis axis seems to have sufficient compensation capabilities. However, study results suggest that primary gonadal dysfunction may predispose to torsion.

IMPACT

Significant differences exist between the literature data and own results on the formation of antibodies and hormonal changes due to testicular torsion in boys. It is a novel, prospective study on antibodies against sperms and Leydig cells in the serum and on hormonal processes occurring as a result of the testicular torsion from the prenatal period to the adolescence with division into pubertal groups. The study has revealed sufficient compensation capabilities of the pituitary-testis axis and no autoimmune process in boys with torsion of the testis.

Reference range and cutoff value of serum inhibin B to predict successful sperm retrieval: A cross-sectional study of 30 613 Chinese men

BACKGROUND

The power of inhibin B to predict competent spermatogenesis is not fully understood. The aims of this study were to identify the reliable reference range of inhibin B among normozoospermic men in China and to evaluate the diagnostic accuracy of serum inhibin B level as a complementary predictor of successful sperm retrieval in patients with azoospermia.

METHODS

This was a cross-sectional study. The male partners of 30 613 infertile couples who visited our hospital were investigated between March 2017 and March 2019. We analysed semen parameters, serum levels of reproductive hormones (inhibin B, FSH and testosterone) and sperm retrieval results from PESA/TESE in Chinese men.

RESULTS

The normal reference range of inhibin B was 87.42-299.93 pg/mL among men with normozoospermia in China. Inhibin B levels were negatively correlated with age (r = -.111; P < .001) but positively correlated with total sperm counts in the overall population, reference group and case group (r = .311, r = .208 and r = .444, respectively; P < .001). Stepwise multiple regression analyses revealed that compared with the FSH and testosterone levels, the inhibin B level had the closest relationship with the total sperm count. The best cutoff value of inhibin B for predicting the retrieval outcome of testicular/epididymal sperm was >77.72 pg/mL (sensitivity = 59.14%, specificity = 92.00% and AUC = 0.801). The inhibin B:FSH ratio (cutoff value > 6.98, sensitivity = 56.99%, specificity = 96.00% and AUC = 0.814) performed better than either the inhibin B level or the FSH level alone.

CONCLUSION

A new reference range for serum inhibin B was established in China. However, neither serum inhibin B, FSH nor their ratio is adequate for men to decide whether to undergo PESA/TESE to determine the adequacy of spermatogenesis.

[Diagnosis of congenital sexual maldevelopment in boys with bilateral inguinal cryptorchidism during minipuberty]

BACKGROUND

Cryptorchidism is associated with the risk of infertility and can be a symptom of congenital sexual maldevelopment.

AIM

To assess the functional status of the pituitary gland and sexual glands in boys aged 16 months with bilateral inguinal cryptorchidism and to reveal the congenital sexual maldevelopment during minipuberty.

METHODS

Twenty-one boys aged 16 months (the minipuberty period) with isolated bilateral inguinal cryptorchidism and 40 healthy boys aged 23 months (the control group) were examined. The gonadal status was assessed and serum levels of sex hormones were measured. Molecular genetic testing was performed if there were indications for it.

RESULTS

The results of hormone analysis were used to divide the patients into three groups: group 1 patients with normal serum levels of gonadotropin and sex hormones; group 2 patients with elevated gonadotropin level and low levels of anti-Mllerian hormone (AMH) and inhibin B, and group 3 patients with zero gonadotropin and testosterone levels and low levels of AMH and inhibin B. Group 1 patients had no functional disturbances in the pituitarygonadal system. Failure of Sertoli cells associated with a high risk of infertility was detected in group 2 patients. Group 3 patients were diagnosed with hypogonadotropic hypogonadism verified by molecular genetic tests.

CONCLUSION

Hormonal testing of patients with bilateral inguinal cryptorchidism during minipuberty makes it possible to early detect the congenital sexual maldevelopment.

Fertility induction in hypogonadotropic hypogonadal men

Men with hypogonadotropic hypogonadism (HH) are typically azoospermic, and yet HH is one of the few treatable forms of male infertility. Sperm induction protocols using gonadotrophins aim to replicate the natural endocrine control of spermatogenesis. Previously virilised men with adult-onset HH and normal testicular volume respond well to monotherapy in which human chorionic gonadotrophin (hCG) acts as a long-acting LH-analogue stimulating spermatogenesis. However, this approach is rarely successful for men with congenital HH (CHH) (eg, Kallmann syndrome), for whom combined gonadotrophin therapy (hCG + follicle-stimulating hormone [FSH]) is an absolute requirement to maximise fertility potential. Key baseline predictors of successful spermatogenesis-induction include prior spontaneous testicular development (ie, testicular volume [TV] > 4 mL), serum inhibin B (I_B ) concentration >60 pg/mL and no history of maldescended testes (cryptorchidism).

The serum inhibin B concentration and reference ranges in normozoospermia

OBJECTIVE

Although an inhibin B assay may be useful in the assessment of testicular function in a number of genital conditions, reliable reference ranges are still lacking. The present study sought to establish the reference range for serum inhibin B by applying the updated Gen II assay.

DESIGN

This prospective study included 818 men referred for semen analysis: 377 were normozoospermic (reference group) and 441 presented at least one abnormal semen parameter (case group).

METHODS

Semen parameters were interpreted according to the 2010 World Health Organization manual and David's modified classification for normal morphology. The inhibin B concentration was determined with the current ELISA.

RESULTS

In the reference group, the 2.5th percentile for inhibin B was 92 pg/ml and the 97.5th percentile for FSH was 7.8 IU/l. In the overall population, an inhibin B level <92 pg/ml was associated with increased odds ratio (OR; 95% CI) for oligozoospermia (16.93 (9.82-29.18), P<0.0001), asthenozoospermia (4.87 (2.88-8.10), P<0.0001), and teratozoospermia (2.20 (1.31-3.68), P=0.0026). The combination of a FSH >7.8 IU/l and an inhibin B <92 pg/ml was associated with greater OR for oligozoospermia (98.74 (23.99-406.35), P<0.0001) than for each hormone considered separately.

CONCLUSIONS

A new reference range for serum inhibin B was established by the use of updated immunoassay. The correlations between hormone levels and semen parameters highlighted the importance of establishing these values with respect to the spermogram. When combined with FSH assay, the inhibin B range may be of value in the evaluation of spermatogenesis in a number of male genital conditions.

Microphysiological modeling of the reproductive tract: a fertile endeavor

Preclinical toxicity testing in animal models is a cornerstone of the drug development process, yet it is often unable to predict adverse effects and tolerability issues in human subjects. Species-specific responses to investigational drugs have led researchers to utilize human tissues and cells to better estimate human toxicity. Unfortunately, human cell-derived models are imperfect because toxicity is assessed in isolation, removed from the normal physiologic microenvironment. Microphysiological modeling often referred to as 'organ-on-a-chip' or 'human-on-a-chip' places human tissue into a microfluidic system that mimics the complexity of human in vivo physiology, thereby allowing for toxicity testing on several cell types, tissues, and organs within a more biologically relevant environment. Here we describe important concepts when developing a repro-on-a-chip model. The development of female and male reproductive microfluidic systems is critical to sex-based in vitro toxicity and drug testing. This review addresses the biological and physiological aspects of the male and female reproductive systems in vivo and what should be considered when designing a microphysiological human-on-a-chip model. Additionally, interactions between the reproductive tract and other systems are explored, focusing on the impact of factors and hormones produced by the reproductive tract and disease pathophysiology.

The effect of toxoplasmosis on the level of some sex hormones in males blood donors in Baghdad

Toxoplasma gondii is a unique intracellular parasite, which infect a large proportion of the world population, but uncommonly causes clinically significant disease. The present study was performed to estimate the prevalence of toxoplasmosis in 400 apparently healthy blood donor males, their ages were between 18 and 57 years using enzyme linked immunosorbent assay, and to examine the effects of infection on total testosterone, free testosterone and follicle stimulating hormone (FSH) levels in their sera. Seroprevalence showed 10 (2.5 %) and 121 (30 %) of them had IgM and IgG antibodies respectively. Both acute and chronic toxoplasmosis in males recorded higher significant (P < 0.05) mean concentration for total and free testosterone hormone, they were 12.188 ± 0.73, 7.837 ± 0.52 ng/ml and 44.121 ± 1.76, 27.984 ± 0.94 pg/ml respectively. The mean concentration of FSH revealed non-significant (P < 0.05) differences in both disease activities, they were 6.41 ± 0.47 and 6.515 ± 0.51 IU/ml respectively.

Inhibin B levels in hypothyroid males

BACKGROUND

The primary role of inhibin B is the regulation of gametogenesis via negative feedback on the production of follicle stimulating hormone (FSH) by the pituitary.

METHODS

We studied 14 males with primary hypothyroidism due to various etiologies to determine if they exhibited hypogonadotrophic hypogonadism involving the reproductive segment of the gonadotrophic axis. Levels of inhibin B, FSH, luteinizing hormone, testosterone, free thyroxine, and thyrotropin were measured.

RESULTS

The mean level of inhibin B in males with primary hypothyroidism was found to be approximately half that of normal males. The FSH level remained within the normal range and no reciprocal increase was observed as occurs in other conditions with reduced inhibin B.

CONCLUSIONS

Our results indicate that primary hypothyroidism has a significant effect on inhibin B levels without reciprocal increase in FSH, which is consistent with a hypogonadotrophic hypogonadal state affecting the reproductive segment of the gonadotrophic axis.

The male reproductive system in classic galactosemia: cryptorchidism and low semen volume

Previous studies examining reproductive parameters in men with galactosemia have inconsistently demonstrated abnormalities. We hypothesized that men with galactosemia may demonstrate evidence of reproductive dysfunction. Pubertal history, physical examination, hormone levels and semen analyses were examined in 26 males with galactosemia and compared to those in 46 controls. The prevalence of cryptorchidism was higher in men with galactosemia than in the general population [11.6% vs. 1.0% (95%CI: 0.75-1.26; p <0.001)]. Testosterone (461±125 vs. 532± 33 ng%; p=0.04), inhibin B (144±66 vs. 183±52 pg/mL; p=0.002) and sperm concentration (46±36 vs. 112±75×10(6) spermatozoa/mL; p=0.01) were lower and SHBG was higher (40.7±21.5 vs 26.7±14.6; p=0.002) in men with galactosemia compared to controls. Semen volume was below normal in seven out of 12 men with galactosemia. Men with galactosemia have a higher than expected prevalence of cryptorchidism and low semen volumes. The subtle decrease in testosterone and inhibin B levels and sperm count may indicate mild defects in Sertoli and Leydig cell function, but does not point towards severe infertility causing reproductive impairment. Follow-up studies are needed to further determine the clinical consequences of these abnormalities.

Age-dependent inhibin B concentration in relation to FSH and semen sample qualities: a study in 2448 men

Inhibin B is an important serum marker of spermatogenesis, whereas sensitivity and predicting power for the spermatogenic situation at several ages are under debate. We performed a retrospective analysis of data from 2448 men who attended our University-based male infertility clinic to evaluate inhibin B in relation to age and semen sample qualities in comparison with FSH. Moreover, the range of inhibin B in 82 nonobstructive azoospermic patients was correlated with the sperm retrieval in testicular sperm extraction procedures. Inhibin B correlated with FSH (Spearman rank correlation (R)=−0.50; P<0.00001). Inhibin B and inhibin B/FSH ratio (IFR) showed an inverse U-shaped dependence on age, whereas FSH showed a U-shaped dependence on age (optimum 20–40 years). However, in men with normal spermiograms inhibin B concentrations did not differ between age groups. Their levels of inhibin B amounted to 130.5, 54.5–247 ng/l (median, 10th–90th precentile), and of IFR to 38.3, 12.5–104.8 (median, 10th–90th percentile), which might be taken as the reference range. Using the 10th percentile of IFR, correct classification in normal or pathological semen groups was achieved in 99.1%. The percentage of aniline blue-negative spermatozoa, i.e. mature spermatozoa with protamines, did not correlate with FSH (P>0.05) but with inhibin B (R=0.15, P<0.001). The probability of retrieving testicular spermatozoa decreased with declining inhibin B: <20 ng/l sperm could never be found. Our results from a large group of men with a wide spectrum of semen qualities allow estimating reference values for inhibin B and IFR. Inhibin B and especially the IFR are more sensitive markers of male infertility than FSH alone.

Pituitary macroadenoma: a rare cause of thyrotoxic hypokalaemic periodic paralysis

Thyrotoxic hypokalaemic periodic palsy (THPP) is a well-recognised but under-diagnosed complication of hyperthyroidism and is commonly seen in Asian males. Patients usually present fully conscious with acute onset of severe motor weakness. Baseline investigation reveals severe hypokalaemia due to Na(+)/K(+) ATPase overactivity causing a massive influx of intracellular potassium ions. The most common cause of THPP identified in the medical literature is Graves' disease. We report an interesting and unusual case of THPP due to previously undiagnosed hyperthyroidism secondary to a pituitary macroadenoma. The patient was consequently found to have a tumour secreting gonadotropin and thyrotropin.

The reproductive-cell cycle theory of aging: an update

The Reproductive-Cell Cycle Theory posits that the hormones that regulate reproduction act in an antagonistic pleiotrophic manner to control aging via cell cycle signaling; promoting growth and development early in life in order to achieve reproduction, but later in life, in a futile attempt to maintain reproduction, become dysregulated and drive senescence. Since reproduction is the most important function of an organism from the perspective of the survival of the species, if reproductive-cell cycle signaling factors determine the rate of growth, determine the rate of development, determine the rate of reproduction, and determine the rate of senescence, then by definition they determine the rate of aging and thus lifespan. The theory is able to explain: 1) the simultaneous regulation of the rate of aging and reproduction as evidenced by the fact that environmental conditions and experimental interventions known to extend longevity are associated with decreased reproductive-cell cycle signaling factors, thereby slowing aging and preserving fertility in a hostile reproductive environment; 2) two phenomena that are closely related to species lifespan-the rate of growth and development and the ultimate size of the animal; 3). the apparent paradox that size is directly proportional to lifespan and inversely proportional to fertility between species but vice versa within a species; 4). how differing rates of reproduction between species is associated with differences in their lifespan; 5). why we develop aging-related diseases; and 6). an evolutionarily credible reason for why and how aging occurs-these hormones act in an antagonistic pleiotrophic manner via cell cycle signaling; promoting growth and development early in life in order to achieve reproduction, but later in life, in a futile attempt to maintain reproduction, become dysregulated and drive senescence (dyosis). In essence, the Reproductive-Cell Cycle Theory can explain aging in all sexually reproductive life forms.

Pilot study of serum inhibin B as a potential marker of testosterone doping in weight lifting men

OBJECTIVE

The aim of this study was to explore effectors of the pituitary-testicular axis suitable as potential biochemical markers to screen for testosterone doping.

DESIGN

Pilot study with male bodybuilding athletes with a self-reported history of testosterone doping (repeated intramuscular administration of testosterone preparations, last injection 8 weeks or less ago) compared with an equal sized control group matched for sex, age, and body mass index.

SETTING

Endocrine outpatients.

PARTICIPANTS

Fifteen healthy young men of white background.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Inhibin B, testosterone, luteinizing hormone (LH), follicle-stimulating hormone (FSH).

RESULTS

Although the levels of testosterone, LH, and FSH did not differ between the 2 groups, the serum concentrations of inhibin B in individuals with a history of testosterone doping were exclusively at or below the lower limit of the normal range for adult men (100-400 pg/mL). Inhibin B was significantly lower in those men who used testosterone for weight lifting (76.1 +/- 36.3 ng/L [mean +/- SD]) than in controls (182.1 +/- 35.4 ng/L).

CONCLUSION

A low concentration of serum inhibin B may reflect the application of exogenous testosterone and appears to be a potential marker associated with anabolic androgenic steroid doping.

Biochemical and physiological aspects of endogenous androgens

This review attempts to give a synopsis of the major aspects concerning the biochemistry of endogenous androgens, supplemented with several facets of physiology, particularly with respect to testosterone. Testosterone continues to be the most common adverse finding declared by World Anti-Doping Agency accredited laboratories, such samples having an augmented testosterone to epitestosterone ratio. Knowledge regarding the precursors and metabolism of endogenous testosterone is therefore fundamental to understanding many of the issues concerning doping with testosterone and its prohormones, including the detection of their administration. Further, adverse findings for nandrolone are frequent, but this steroid and 19-norandrostenedione are also produced endogenously, an appealing hypothesis being that they are minor by-products of the aromatization of androgens. At sports tribunals pertaining to adverse analytical findings of natural androgen administration, experts often raise issues that concern some aspect of steroid biochemistry and physiology. Salient topics included within this review are the origins and interconversion of endogenous androgens, the biosynthesis of testosterone and epitestosterone, the mechanism of aromatization, the molecular biology of the androgen receptor, the hypothalamic-pituitary-testicular axis, disturbances to this axis by anabolic steroid administration, the transport (binding) of androgens in blood, and briefly the metabolism and excretion of androgens.

Effects of oestradiol on gonadotrophin levels in normal and castrated men

CONTEXT

Testosterone inhibits gonadotrophin release in men either directly or after aromatization to oestradiol. We hypothesized that in males the androgen receptor-mediated effect of testosterone on LH release is negligible relative to that of oestradiol.

OBJECTIVE

To compare the effect of experimentally induced variations of plasma oestradiol levels on LH levels in normal (physiological testosterone levels) and castrated men (very low testosterone levels).

DESIGN

Prospective, open label, intervention.

SUBJECTS AND INTERVENTIONS

We suppressed endogenous oestradiol in 10 young men with letrozole 2.5 mg once daily. In these men and in 10 young healthy castrated men, we restored plasma oestradiol levels with oestradiol patches (first week 100 mug/day, second week 50 mug/day, third week 25 mug/day and fourth week no oestradiol patch).

MEASUREMENTS

The effect of the intervention on plasma levels of LH were monitored and compared between the groups.

RESULTS

With the intervention, the mean plasma oestradiol level in the two groups varied from supraphysiological to below the lower reference range. Levels of LH mirrored plasma oestradiol levels in both the groups, as did testosterone in the intact group. Despite similar oestradiol levels, mean levels of LH were significantly higher in the castrated group compared to the intact group for all doses of oestradiol, and supraphysiological levels of oestradiol were unable to suppress LH into the physiological range in the castrated group.

CONCLUSIONS

Physiological plasma oestradiol levels have a substantial suppressive effect on LH in men. However, low-normal testosterone levels are a prerequisite for suppression of LH into the normal range.

Factors that influence entry into stages of the menopausal transition

OBJECTIVE

The aim of this study was to estimate the probabilities and identify risk factors for entering the menopausal transition and moving into each subsequent transition stage.

METHODS

Estimations of probabilities of entry into each menopausal transition stage and predictors associated with each transition stage were conducted in a population-based cohort of midlife women.

RESULTS

The likelihood of entering the menopausal transition and moving into each subsequent stage was increased for each unit increase in follicle-stimulating hormone (FSH) (P < 0.001) and with each unit decrease in inhibin B (P < 0.001) in the adjusted multivariable model. The largest observed change in average FSH levels was the comparison of women in the late transition (stage 4), with an average of 24.78 mIU/mL, to those in the early transition (stage 3), with 10.38 mIU/mL. Women experiencing this amount of change in FSH had an odds of transitioning from stages 3 to 4 of 1.90 (95% CI, 1.86-1.95). Decreases in inhibin B resulted in odds ratios similar to the magnitude of changes in FSH. Current smoking increased the odds of transition into each stage by approximately 30% (odds ratio, 1.30; 95% CI, 1.28-1.32). Average estradiol levels did not change dramatically between stages. However, higher estradiol significantly increased the odds of entering the transition (P = 0.013). Age and race predicted transitions into some but not all stages. Body mass index, alcohol use, and age at menarche did not predict entrance into any stage of the menopausal transition after adjusting for other study variables.

CONCLUSIONS

These results show that increased FSH, decreased inhibin B, and smoking strongly predict entry into the earliest stages of the menopausal transition as defined by changes in bleeding patterns. African Americans entered the transition before white women, but race did not predict entry into late transition stages. Higher estradiol levels predict entry into the earliest transition stage but not subsequent stages.

Ghrelin suppresses secretion of FSH in males

BACKGROUND

Ghrelin decreases the secretion of LH probably by suppressing the release of hypothalamic GnRH. So far however, there is no evidence that ghrelin affects also the secretion of FSH in humans, the other gonadotrophin regulated by GnRH.

OBJECTIVE

Our objective was to study the effect of ghrelin on secretion of FSH in humans. DESIGN/STUDY SUBJECTS: Nocturnal (20:00-07:00 h) secretion profiles of FSH were measured in 10 healthy males (25.3 +/- 3.2 years) twice, receiving 50 microg ghrelin or placebo at 22:00, 23:00, 24:00, and 01:00 h, in this single-blind, randomized, cross-over study.

RESULTS

Mean FSH plasma levels were significantly (P < 0.05) lower with ghrelin than placebo between 01:00 and 02:20. Consistently, a significant decrease from baseline was only observed in the ghrelin but not in the placebo condition.

CONCLUSION

This study provides first evidence that ghrelin suppresses the secretion of FSH in humans.

The relative role of gonadal sex steroids and gonadotropin-releasing hormone pulse frequency in the regulation of follicle-stimulating hormone secretion in men

OBJECTIVE

Our objective was to determine the importance of testosterone (T), estradiol (E(2)), and GnRH pulse frequency to FSH regulation in men.

DESIGN

This was a prospective study with four arms.

SETTING

The study was performed at the General Clinical Research Center.

PATIENTS OR OTHER PARTICIPANTS

There were 20 normal (NL) men and 15 men with idiopathic hypogonadotropic hypogonadism (IHH) who completed the study.

INTERVENTION

Medical castration and inhibition of aromatase were achieved using ketoconazole x 7 d with: 1) no sex steroid addback, 2) T addback starting on d 4, and 3) E(2) addback starting on d 4. IHH men in these arms received GnRH every 120 min. In a further six IHH men receiving ketoconazole with no addback, GnRH frequency was increased to 35 min for d 4-7. Blood was drawn every 10 min x 12 h at baseline, overnight on d 3-4 and 6-7.

MAIN OUTCOME MEASURES

Mean FSH was calculated from the pool of each frequent sampling study.

RESULTS

In NL men FSH levels increased from 5.1 +/- 0.7 to 8.7 +/- 1.3 and 9.7 +/- 1.5 IU/liter (P < 0.0001). T caused no suppression of FSH. E(2) reduced FSH from 12.4 +/- 1.8 to 9.3 +/- 1.3 IU/liter (P < 0.05). In IHH men on GnRH every 120 min, FSH levels went from 6.0 +/- 1.6 to 9.0 +/- 3.0 and 11.9 +/- 4.3 (P = 0.07). T caused no suppression of FSH. E(2) decreased FSH such that levels on d 6-7 were similar to baseline. Increasing GnRH frequency to 35 min had no impact on FSH.

CONCLUSIONS

The sex steroid component of FSH negative feedback in men is mediated by E(2). Increasing GnRH frequency to castrate levels has no impact on FSH in the absence of sex steroids. When inhibin B levels are NL, sex steroids exert a modest effect on FSH.