Inhibin B: a novel marker of spermatogenesis

Antibody fragments targeting the extracellular domain of follicular stimulating hormone receptor for contraception in male dogs and cats

The increased LH levels resulting from the absence of negative feedback after castration has been linked to long-term health issues. A need exists for an alternative contraceptive agent that functions without interfering the LH pathways. This study aimed to develop antibody fragments against the follicular-stimulating hormone receptor (anti-FSHr) using phage-display technology and evaluate its effects on Sertoli cell functions. Phage clones against the extracellular domain of dog and cat FSHr selected from an antibody fragment phagemid library were analyzed for binding kinetics by surface plasmon resonance. Sertoli cells were isolated from testes of adult animals (five dogs and five cats). Efficacy test was performed by treating Sertoli cell cultures (SCCs) with anti-FSHr antibody fragments compared with untreated in triplicates. Expressions of androgen binding protein (ABP), inhibin subunit beta B (IHBB) and vascular endothelial growth factor A (VEGFA) mRNA in SCCs were quantified by RT-qPCR. The results demonstrated that the molecular weight of the purified dog and cat anti-FSHr antibody fragment was 25 kDa and 15 kDa, respectively. Based on protein molecular weight, the antibody fragment of dogs and cats was therefore, so-called single-chain variable fragments (scFv) and nanobody (nb), respectively. The binding affinity with dissociation constant (KD) was 2.32 × 10-7 M and 2.83 × 10-9 M for dog and cat anti-FSHr antibody fragments, respectively. The cross-binding kinetic interactions between the dog anti-FSHr scFv and the cat ECD of FSHr could not be fitted to the curves to determine the binding kinetics. However, the cross-binding affinity KD between the cat anti-FSHr nb and the dog ECD FSHr was 1.75 × 10-4 M. The mRNA expression of ABP, IHBB and VEGFA in SCCs was less (P < 0.05) in both dogs (12.26, 4.07 and 5.11 folds, respectively) and cats (39.53, 14.07 and 20.29 folds, respectively) treated with anti-FSHr antibody fragments, indicating the Sertoli cell functions were suppressed. In conclusion, this study demonstrated the establishment of species-specific antibody fragments against FSHr in SCCs for dogs and cats. The fragment proteins illustrate potential to be developed as non-surgical contraceptive agent targeting FSHr in companion animals.

Anti-Müllerian hormone predicts positive sperm retrieval in men with idiopathic non-obstructive azoospermia-findings from a multi-centric cross-sectional study

STUDY QUESTION

Is it possible to identify a reliable marker of successful sperm retrieval (+SR) in men with idiopathic non-obstructive azoospermia (iNOA) undergoing microdissection testicular sperm extraction (mTESE)?

SUMMARY ANSWER

A higher likelihood of +SR during mTESE is observed in men with iNOA and lower preoperative serum anti-Müllerian hormone (AMH) levels, with good predictive accuracy achieved using an AMH threshold of <4 ng/ml.

WHAT IS KNOWN ALREADY

AMH has been previously linked to +SR in men with iNOA undergoing mTESE prior to ART.

STUDY DESIGN, SIZE, DURATION

A multi-centre cross-sectional study was carried out with a cohort of 117 men with iNOA undergoing mTESE at three tertiary-referral centres.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Data from 117 consecutive white-European men with iNOA presenting for primary couple's infertility associated with a pure male factor at three centres were analysed. Descriptive statistics was applied to compare patients with negative (-SR) versus +SR at mTESE. Multivariate logistic regression models were fitted to predict +SR at mTESE, after adjusting for possible confounders. Diagnostic accuracy of the factors associated with +SR was assessed. Decision curve analyses were used to display the clinical benefit.

MAIN RESULTS AND THE ROLE OF CHANCE

Overall, 60 (51.3%) men had an -SR and 57 (48.7%) had a +SR at mTESE. Patients with +SR had lower levels of baseline AMH (P = 0.005) and higher levels of estradiol (E2) (P = 0.01). At multivariate logistic regression analysis, lower levels of AMH (odds ratio: 0.79; 95% CI: 0.64-0.93, P = 0.03) were associated with +SR at mTESE, after adjusting for possible confounders (e.g. age, mean testicular volume, FSH, and E2). A threshold of AMH <4 ng/ml achieved the highest accuracy for +SR at mTESE, with an AUC of 70.3% (95% CI: 59.8-80.7). Decision curve analysis displayed the net clinical benefit of using an AMH <4 ng/ml threshold.

LIMITATIONS, REASONS FOR CAUTION

There is a need for external validation in even larger cohorts, across different centres and ethnicities. Systematic reviews and meta-analysis to provide high level of evidence are lacking in the context of AMH and SR rates in men with iNOA.

WIDER IMPLICATIONS OF THE FINDINGS

Current findings suggest that slightly more than one in two men with iNOA had -SR at mTESE. Overall, men with iNOA with lower levels of AMH had a significantly higher percentage of successful SR at surgery. A threshold of <4 ng/ml for circulating AMH ensured satisfactory sensitivity, specificity, and positive predictive values in the context of +SR at mTESE.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by voluntary donations from the Urological Research Institute (URI). All authors declare no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

Impaired Testicular Function without Altering Testosterone Concentration Using an Anti-Follicular-Stimulating Hormone Receptor (Anti-FSHr) Single-Chain Variable Fragment (scFv) in Long-Tailed Macaques (Macaca fascicularis)

FSHr antibodies have been shown to inhibit the differentiation of spermatogonia to primary spermatocytes, resulting in infertility without a pathological effect on reproductive organs. The aim of this study was to develop single-chain variable fragments (scFvs) against the follicular-stimulating hormone receptor (anti-FSHr) using phage-display technology and to evaluate the effects of intratesticular administration of the anti-FSHr scFv on testicular function and testosterone production. A phage clone against the extracellular domain of FSHr selected from a scFv phagemid library was analyzed for binding kinetics by surface plasmon resonance. Using ultrasound guidance, three adult macaques (M. fascicularis) were administered with 1 mL of 0.4 mg/mL anti-FSHr scFv (treatment) and 1 mL sterile phosphate buffer solution (control) into the left and right rete testis, respectively. Testicular appearance and volume, ejaculate quality, and serum testosterone levels were recorded on day 0 (before injection) and on days 7, 28, and 56 (after injection). Testicular tissue biopsies were performed on day 7 and day 56 to quantify the mRNA expressions of androgen binding protein (ABP), inhibin subunit beta B (IHBB), and vascular endothelial growth factor A (VEGFA). The results demonstrated that the anti-FSHr scFv molecule was calculated as 27 kDa with a dissociation constant (K_D) of 1.03 µM. The volume of the anti-FSHr scFv-injected testicle was reduced on days 28 and 56 compared with day 0 (p < 0.05). Total sperm number was reduced from day 0 (36.4 × 10⁶ cells) to day 56 (1.6 × 10⁶ cells) (p < 0.05). The percentage of sperm motility decreased from day 0 (81.7 ± 1.0%) to day 7 (23.3 ± 1.9%), day 28 (41.7 ± 53.4%), and day 56 (8.3 ± 1.9%) (p < 0.05). Sperm viability on day 0 was 86.8 ± 0.5%, which reduced to 64.2 ± 1.5%, 67.1 ± 2.2%, and 9.3 ± 1.1% on days 7, 28, and 56, respectively (p < 0.05). The expression of ABP and VEGFA on days 7 (14.2- and 3.2-fold) and 56 (5.6- and 5.5-fold) was less in the scFv-treated testicle compared with the controls (p < 0.05). On day 56, the expression of IHBB was less (p < 0.05) in the treated testis (1.3-fold) compared with the controls. Serum testosterone levels were unchanged throughout the study period (p > 0.05). This study characterized the anti-FSHr scFv and demonstrated that treatment with anti-FSHr ameliorates testicular function without altering testosterone levels, offering a potential alternative contraceptive for the long-tailed macaques.

Impaired semen quality, an increase of sperm morphological defects and DNA fragmentation associated with environmental pollution in urban population of young men from Western Siberia, Russia

Poor sperm morphology and an elevated DNA fragmentation level are considered to be related to spermiogenesis malfunctions as a result of genetic mutations and effects of environmental factors, including industrial pollution. Standardized cross-sectional population studies of sperm morphology defects and sperm DNA fragmentation, especially in regions with increased environmental pollution may be helpful to investigate an influence of industrial pollution and other population-related factors on spermiogenesis process. The aim of present study was to estimate an influence industrial pollution on sperm morphogenesis and sperm DNA fragmentation in men from the general population of the Western Siberia. The Novosibirsk and Kemerovo cities are located to same climatic conditions in Western Siberia but the Kemerovo city is characterized by increased environmental pollution especially by particulate matter (PM). The male volunteers living in Novosibirsk (n = 278) and Kemerovo (n = 258) were enrolled. Percentages of sperm morphological defects are counted after staining native ejaculate smears by Diff-Quick kits. DNA fragmentation was estimated by a SCSA technique. The residents of Kemerovo were characterized by lowered sperm count and sperm motility, elevated DNA fragmentation, poor sperm morphology and increased incidence of morphological effects of head (pyriform, elongated, round, abnormal acrosome and vacuolated chromatine), asymmetrical neck insertion and excess residual cytoplasm. Moreover, elevated DNA fragmentation was associated with lowered sperm count, sperm motility and increased percentages of several sperm morphology defects, with the place of residence affecting the relationships between conventional semen parameters, sperm morphology and DNA fragmentations. Our study suggests that excessive sperm head elongation and impaired acrosome formation can contribute to sperm morphology deterioration in men from polluted areas. Regional features in the relationships between sperm morphology, sperm count and DNA fragmentation were shown, suggesting an importance of studying sperm morphology pattern in men from different regions.

The role of leptin and obesity on male infertility

PURPOSE OF REVIEW

Several studies suggest a strong association between leptin, obesity, and infertility with respect to the hypothalamic-pituitary-gonadal (HPG) axis, androgen regulation, and sperm production, but the direct mechanistic association between these is still largely unexplored. This review focuses on understanding the association between leptin, obesity, and male infertility.

RECENT FINDINGS

Obesity is linked to fertility dysfunction in both genders. Obesity in men may affect their fertility by impaired spermatogenesis, reduced testosterone levels, erectile dysfunction, and poor libido by putatively targeting the HPG and hypothalamic-pituitary-adrenal axes. Leptin plays key roles in many metabolic functions, including reproduction. High concentrations of leptin have been found in infertile men with disorders affecting the testicular parenchyma, including nonobstructive azoospermia, oligozoospermia, and oligo-astheno-teratozoospermia. Additionally, serum leptin levels have negative associations with serum testosterone levels and sperm parameters and positive associations with serum follicle-stimulating hormone and luteinizing hormone levels and abnormal sperm morphology.

SUMMARY

Excessive leptin production may be a significant contributor to the development of androgen insufficiency and reduced reproductive function in obese men. Understanding the relation between leptin, obesity, and reproduction may shed light on future targeted treatments for male infertility.

Dietary supplements in the management of varicocele-induced infertility: A review of potential mechanisms

Varicocele is a main cause of lower production of spermatozoon and infertility with multiple pathophysiological mechanisms. In the past decades, the use of dietary supplements has significantly increased due to both the modern lifestyle and the food shortages of the industrialised countries. The purpose of this review paper is to collect scientific evidences from basic and clinical studies which support the use of dietary supplements to define the clinical framework for patients with varicocele. In the present review, we used keywords such as dietary supplements, varicocele, male infertility, oxidative stress, DNA fragmentation, sperm parameters to find the proper articles. The standard search biomedical engines were used for seeking the papers. The use of dietary supplements such as minerals, vitamins and antioxidants has an essential role in the prevention and treatment of varicocele by increasing the levels of antioxidant enzymes (e.g. peroxidase, superoxide dismutase and catalase) and decreasing the levels of inflammatory markers (e.g. tumour necrosis factor-α, interleukin-6 and interleukin-1) in testis. According to the results, the dietary supplements may alleviate the spermatogenesis in varicocele patients through different mechanisms such as suppression of stress oxidative and inflammation in testicular tissue.

Ethanolic extract of Moringa oleifera leaves alleviate cyclophosphamide-induced testicular toxicity by improving endocrine function and modulating cell specific gene expression in mouse testis

ETHNOPHARMACOLOGICAL RELEVANCE

Moringa oleifera Lam. is known for its nutritional and ethno medicinal values due to the presence of wide array of phytochemicals with multiple biological activities. We have previously reported that ethanolic extract of Moringa oleifera leaves (MOE) ameliorated cyclophosphamide (CP)-induced testicular toxicity and improved functional integrity of spermatozoa as well as spermatogenic cells.

AIM OF THE STUDY

The present study was planned to investigate whether the mitigation of CP-induced testicular toxicity by MOE is mediated via modulation of endocrine profile, genes associated with function of different cell types and enhancement of DNA repair response in spermatogonial cells.

MATERIALS AND METHODS

Adult Swiss albino mice (8 week) were injected with CP (100 mg/kg, one dose in a week for 3 weeks) and MOE (100 mg/kg, 5 doses in a week for 4 weeks) either alone or in combination intraperitoneally. At 35 day post CP injection (first dose), the functional characteristics such as count, motility, head morphology and DNA integrity were assessed in epididymal spermatozoa. Key reproductive hormones like testosterone, follicle stimulating hormone (FSH) and Inhibin B concentration were analyzed in serum and testis. In addition, mRNA expression of genes pertaining to the function of Leydig, Sertoli and spermatogonial cells as well as antioxidant enzymes were evaluated in the testis. To understand the DNA damage and repair process in germ cells, prepubertal (2 week) mice were administered with single dose of CP (200 mg/kg) and/or MOE (100 mg/kg) and analyzed for expression of DNA damage (γ-H2AX, P53 and Caspase3) and repair genes (Rad51 and Ku80) in isolated spermatogonial cells at various time points after treatment.

RESULTS

CP administration resulted in decrease in count, motility and increase in morphological defects and DNA damage in spermatozoa. Testosterone level was marginally decreased while there was a significant increase in FSH (p < 0.001) and decrease in inhibin B (p < 0.05) observed in CP treated mice. Administration of MOE prior to CP, improved sperm functional characteristics, decreased FSH and increased inhibin B levels. Expression of Abp was down-regulated while Transferrin, Fshr and Gata4 (Sertoli cell specific genes) were up-regulated in testis treated with CP. Administration of CP down-regulated the expression of Oct4 and Ddx4 (Spermatogonia specific genes). MOE administration was shown to ameliorate CP-induced damage by modulating the expression of genes specific to Sertoli and spermatogenic cells. Furthermore, MOE treatment reduced CP-induced DNA damage as evident from lower percentage of γ-H2AX positive spermatogonial cells.

CONCLUSION

Administration of MOE mitigated CP-induced testicular damage by improving blood and, intra-testicular hormonal milieu as well as modulating the expression of genes pertaining to Sertoli and spermatogonial cells.

Kisspeptin and Testicular Function-Is it Necessary?

The role of kisspeptin in stimulating hypothalamic GnRH is undisputed. However, the role of kisspeptin signaling in testicular function is less clear. The testes are essential for male reproduction through their functions of spermatogenesis and steroidogenesis. Our review focused on the current literature investigating the distribution, regulation and effects of kisspeptin and its receptor (KISS1/KISS1R) within the testes of species studied to date. There is substantial evidence of localised KISS1/KISS1R expression and peptide distribution in the testes. However, variability is observed in the testicular cell types expressing KISS1/KISS1R. Evidence is presented for modulation of steroidogenesis and sperm function by kisspeptin signaling. However, the physiological importance of such effects, and whether these are paracrine or endocrine manifestations, remain unclear.

Comparison of Serum Inhibin B and Follicle-Stimulating Hormone (FSH) Level between Normal and Infertile Men in Yaoundé

Objective

Hormones play a vital role in initiating and maintaining male reproductive function. The present study explores the influence and predictive ability of two reproductive hormones on semen quality among men who were partners in an infertile couple.

Design

During our cross sectional study, men were recruited from private and public hospital and laboratories for clinical evaluation of fertility status.

Methods

Fresh semen samples were assessed for quality (concentration, motility and morphology) according to the 2010 World Health Organization manual and the serum levels of hormones, including follicle-stimulating hormone (FSH), Inhibin B was measured (ELISA).

Results

We found a significant difference in the two groups regarding sperm concentration (p < 0.0001), total sperm count (p < 0.0001), total sperm count (p < 0.0001), total sperm count (p < 0.0001), total sperm count (p < 0.0001), total sperm count (

Conclusion

Consistent with other studies, our results show strong association between semen quality and FSH and Inhibin B.

Effects of valganciclovir on spermatogenesis in renal transplant patients - results of a multicenter prospective nonrandomized study

Ganciclovir (GCV) inhibits spermatogenesis in preclinical studies but long‐term effects on fertility in renal transplant patients are unknown. In a prospective, multicenter, open‐label, nonrandomized study, male patients were assigned to Cohort A [valganciclovir (VGCV), a prodrug of GCV] (n = 38) or B (no VGCV) (n = 21) by cytomegalovirus prophylaxis requirement. Changes in semen parameters and DNA fragmentation were assessed via a mixed‐effects linear regression model accounting for baseline differences. Sperm concentration increased post‐transplant, but between baseline and treatment end (mean 164 days Cohort A, 211 days Cohort B), the model‐based change was lower in Cohort A (difference: 43.82 × 10⁶/ml; P = 0.0038). Post‐treatment, sperm concentration increased in Cohort A so that by end of follow‐up (6 months post‐treatment) changes were comparable between cohorts (difference: 2.09 × 10⁶/ml; P = 0.92). Most patients’ sperm concentration improved by end of follow‐up; none with normal baseline concentrations (≥20 × 10⁶/ml) were abnormal at end of follow‐up. Changes in seminal volume, sperm motility/morphology, DNA fragmentation, and hormone levels were comparable between cohorts at end of follow‐up. Improvement in semen parameters after renal transplant was delayed in men receiving VCGV, but 6 months post‐treatment parameters were comparable between cohorts.

Prevalence of Testicular Adrenal Rest Tumor and Factors Associated with Its Development in Congenital Adrenal Hyperplasia

BACKGROUND

Testicular adrenal rest tumors (TART) can cause infertility in congenital adrenal hyperplasia (CAH) males.

AIMS

To determine TART prevalence in patients with CAH due to 21-hydroxylase deficiency (21-OHD) and evaluate possible factors associated with its development.

METHODS

This is a descriptive and analytical cross-sectional study evaluating males with the classical form of 21-OHD through testicular ultrasonography and serum inhibin B dosages. Data on prescribed glucocorticoid dose and serum levels of 17- hydroxyprogesterone (17-OHP), androstenedione (Andro), ACTH, renin, and LH were obtained from medical records.

RESULTS

Thirty-eight males were evaluated. The mean age on ultrasonography was 15.2 ± 6.7 (3-27) years. Nine patients (23.7%) had TART, 4 of them were prepubertal and the youngest was 5 years old. No association was found between TART and 21-OHD phenotype, glucocorticoid dose, or 17-OHP, ACTH, LH, renin, and inhibin B levels measured in the 6 preceding years. However, 50% of the patients who presented increased Andro 2 years prior to the evaluation had TART (p = 0.018, OR = 8.00 [95% CI: 1.42-44.92]), whereas in the normal Andro group only 16.7% had tumors.

CONCLUSION

This study showed that TART can occur in prepubertal patients and that disease control could be a factor associated with its development. Therefore, we suggest investigating TART development early in childhood, mainly in poorly controlled 21-OHD patients.

Gestational and lactational exposure to bisphenol AF in maternal rats increases testosterone levels in 23-day-old male offspring

During prenatal and postnatal development, exposure to environmental chemicals with estrogenic activity, such as bisphenol AF (BPAF), may result in reproductive disorders. Currently, the mechanisms behind such disorders in male offspring induced by gestational and lactational exposure to BPAF remain poorly understood. Here, female rats from gestational day (GD) 3-19 were exposed to 100 mg BPAF/kg/day by oral gavage. On the day of birth (postnatal day (PD) 0), cross-fostering took place between treated and control litters, and cross-fostered mother rats were given BPAF 100 mg/kg/day during the postnatal period (PD 3 to PD 19). HPLC-MS/MS analysis showed that BPAF was transferred via cord blood and lactation, finally bio-accumulating in the offspring testes. Pups exposed to BPAF both prenatally and postnatally showed a significant increase in testis testosterone levels compared with that of the control, while all pups exposed to BPAF showed a significant decrease in testis inhibin B (INHB) levels. Compared with the control, RNA-seq revealed that 279 genes were significantly differentially expressed in the testes of pups exposed to BPAF both prenatally and postnatally, including genes involved in cell differentiation and meiosis. These results indicate that gestational and lactational exposure to BPAF in the mother can impair reproductive function in male offspring.

Human exposure to endocrine disrupting chemicals and fertility: A case-control study in male subfertility patients

BACKGROUND

Dioxins, PCBs, chlorinated pesticides, brominated flame retardants, bisphenol A, triclosan, perfluorinated compounds and phthalates are known as endocrine disrupting chemicals (EDCs).

OBJECTIVES

The aim of our study was to investigate whether higher exposure to EDCs is associated with increased subfertility in men.

METHODS

We measured biomarkers of exposure in 163 men, recruited through four fertility clinics. According to WHO guidelines, we used a total motility count (TMC) of 20 million as cut-off value. We assigned patients to the case group when two semen samples - collected at least one week apart - had a TMC<20 and to the control group when both samples had a TMC≥20. To estimate the risk of subfertility and alteration in sex hormone concentrations we used multivariable-adjusted analysis, using logistic and linear regressions, respectively.

RESULTS

For an IQR increase in serum oxychlordane, the odds ratio for subfertility was 1.98 (95% CI: 1.07; 3.69). Furthermore, men with serum levels of BDE209 above the quantification limit had an odds of 7.22 (1.03; 50.6) for subfertility compared with those having values below the LOQ. Urinary levels of phthalates and triclosan were negatively associated with inhibin B and positively with LH. Urinary bisphenol A correlated negatively with testosterone levels.

CONCLUSIONS

Our study in men showed that internal body concentrations of endocrine disrupting chemicals are associated with an increased risk of subfertility together with alterations in hormone levels. The results emphasize the importance to reduce chemicals in the environment in order to safeguard male fertility.

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.

Is there any relation between anthropometric indices and decrease in seminal parameters?

Objective:

To investigate the influence of anthropometric indices on seminal parameters.

Methods:

Men who underwent treatment for conjugal infertility during the period of October, 2011, to March, 2012, were randomly selected. Patients with any prior diseases related to sperm alterations were excluded. Patients were submitted to an anthropometric evaluation to obtain body mass index, and the seminal analysis was made through a spermogram. Two anthropometric methods of classification were used: body mass index (normal and altered) and abdominal circumference (<94cm and >94cm). Data were analyzed by statistical tests.

Results:

The group with the altered body mass index presented lower volumes of ejaculated volume and a larger percentage of patients with abdominal circumference <94cm presented with progressive forms of spermatozoa below reference values. However, in the statistical tests, there was no significant difference.

Conclusion:

No significant difference was found in the sperm quality relative to the body mass index or abdominal circumference.

Review of clinical trials on effects of oral antioxidants on basic semen and other parameters in idiopathic oligoasthenoteratozoospermia

Infertility affects 50 to 80 million people worldwide. Male factor is a cause of infertility in almost half of cases, mainly due to oligoasthenoteratozoospermia (OAT). With common diagnostic methods no cause can be found in approximately 30% of cases of male infertility due to OAT and these are considered idiopathic. Reactive oxygen species (ROS) play an important role in male infertility and are proved to be higher in infertile men; antioxidants could oppose their effect. The aim of this paper was to review the literature on clinical trials in the period from year 2000 to year 2013 studying the effects of various types of antioxidant supplements on basic and other sperm parameters and pregnancy rates in subfertile males with idiopathic OAT. The majority of studies were randomized and placebo controlled and confirmed beneficial effect of antioxidants on at least one of the semen parameters; the biggest effect was determined on sperm motility. In many of these trials combinations of more antioxidants were assessed. The optimal dosages of one or more antioxidants were not defined. We concluded that antioxidants play an important role in protecting semen from ROS and can improve basic sperm parameters in case of idiopathic OAT.

Biomarkers of chemotherapy-induced testicular damage

Increasing numbers of men are having or wanting children after chemotherapy treatment. This can be attributed to improvements in cancer therapies that increase survival. However, a side effect of most chemotherapy drugs is disruption of spermatogenesis and a drastic reduction in sperm count and quality. Although many men eventually recover reproductive function, as indicated by normal semen analyses, there is no clinical test that can assess sperm quality at a high level of sensitivity. Sperm fluorescent in situ hybridization (i.e., FISH) and several different tests for deoxyribonucleic acid (DNA) fragmentation have been used infrequently in clinical assessment. Animal models of chemotherapy-induced testicular damage are currently being used to identify potential molecular biomarkers that may be translatable to humans-these include sperm messenger RNAs, microRNAs, histone modifications, and DNA methylation patterns. Changes in these molecular measurements are quantitative and sensitive, potentially making them important clinical biomarkers of testicular function after chemotherapy treatment.

Sperm counts and endocrinological markers of spermatogenesis in long-term survivors of testicular cancer

Background:

The objective of this study was to assess markers of spermatogenesis in long-term survivors of testicular cancer (TC) according to treatment, and to explore correlations between the markers and associations with achieved paternity following TC treatment.

Methods:

In 1191 TC survivors diagnosed between 1980 and 1994, serum-follicle stimulating hormone (s-FSH; n=1191), s-inhibin B (n=441), and sperm counts (millions per ml; n=342) were analysed in a national follow-up study in 1998–2002. Paternity was assessed by a questionnaire.

Results:

At median 11 years follow-up, 44% had oligo- (<15 millions per ml; 29%) or azoospermia (15%). Sperm counts and s-inhibin B were significantly lower and s-FSH was higher after chemotherapy, but not after radiotherapy (RT), when compared with surgery only. All measures were significantly more abnormal following high doses of chemotherapy (cisplatin (Cis)>850 mg, absolute cumulative dose) compared with lower doses (Cis ⩽850 mg). Sperm counts were moderately correlated with s-FSH (−0.500), s-inhibin B (0.455), and s-inhibin B : FSH ratio (−0.524; all P<0.001). All markers differed significantly between those who had achieved post-treatment fatherhood and those with unsuccessful attempts.

Conclusion:

The RT had no long-term effects on the assessed markers of spermatogenesis, whereas chemotherapy had. At present, the routine evaluation of s-inhibin B adds little in the initial fertility evaluation of TC survivors.

Testicular failure in boys with Prader-Willi syndrome: longitudinal studies of reproductive hormones

CONTEXT

The pathophysiology of hypogonadism in boys with Prader-Willi Syndrome (PWS) remains uncertain. Several reports described hypogonadotropic hypogonadism, some reported primary gonadal failure, and others a combination of both.

OBJECTIVES

The aim of the study was to evaluate gonadal function over time in boys with PWS and the effect of GH treatment.

MEASUREMENTS

We made a longitudinal assessment of inhibin B, FSH, testosterone, and LH levels in prepubertal boys and male adolescents with PWS.

PATIENTS AND METHODS

We studied 68 boys participating in the Dutch PWS Cohort study. Serum inhibin B, FSH, LH, and testosterone levels were compared with reference values.

RESULTS

Boys with PWS had normal inhibin B levels between 6 months and 10 yr of age, but after onset of puberty, inhibin B levels declined to less than the 5th percentile, and FSH levels increased to more than the 95th percentile. Two years after the onset of puberty and in young adults, inhibin B levels were significantly lower (P=0.008 and P<0.0001), and FSH levels were significantly higher (P=0.034 and P<0.0001) than at onset of puberty. Testosterone levels increased but remained below the 5th percentile, and LH levels increased but not above the 95th percentile. Age showed a significant correlation with inhibin B levels (r=-0.31; P=0.001) after 9 yr of age. GH treatment had no significant effect on inhibin B levels.

CONCLUSION

Our study indicates that the majority of male patients with PWS have primary testicular failure, which becomes apparent after onset of puberty. Hypogonadotropic hypogonadism did not appear to be the main reason of hypogonadism in most boys.

Normal inhibin B levels suggest partial preservation of gonadal function in adult male patients with anorexia nervosa

INTRODUCTION

The impact of undernutrition on endocrine and exocrine gonadatrope function is poorly known in male anorexia nervosa (AN) patients.

AIM

The aim of this study was to compare the pituitary-gonadal function of male AN subjects with that of healthy controls, Kallmann syndrome (KS) patients, and female AN subjects.

METHODS

Observational monocentric cross-sectional study performed in 31 male and 25 female subjects with restrictive-type AN, 22 male and 20 female controls, and nine male KS patients.

MAIN OUTCOME MEASURES

Hormonal parameters are as follows: follicule stimulating hormone (FSH), luteinizing hormone (LH), sex hormone binding globulin, estradiol, testosterone, inhibin B, thyroid hormones, growth hormone (GH), insulin-like growth factor 1 (IGF-1), cortisol, adrenocorticotropic hormone (ACTH), dehydroepiandrosterone sulfate, and leptin.

RESULTS

Similar abnormalities of free T3, GH, IGF-I, cortisol, and leptin were found in men as in AN women with equivalent undernutrition status when compared with corresponding controls. Low levels of LH, FSH were found in both male and female AN patients. In male AN, total testosterone was found lower than in controls but higher than in KS, while a lack of estradiol was noticed in AN women. Sex hormones variations were directly related to weight gain only in AN men. No relationship was found between sex hormones and leptin variation for both sexes. In AN men, inhibin B levels were similar to that of controls and did not correlate with testosterone levels.

CONCLUSIONS

Significant differences of undernutrition impact on gonadal status were noticed between male and female AN subjects, including partial preservation of testosterone release and probable preservation of exocrine function, according to the normal inhibin B levels.

Does weight loss improve semen quality and reproductive hormones? Results from a cohort of severely obese men

Background

A high body mass index (BMI) has been associated with reduced semen quality and male subfecundity, but no studies following obese men losing weight have yet been published. We examined semen quality and reproductive hormones among morbidly obese men and studied if weight loss improved the reproductive indicators.

Methods

In this pilot cohort study, 43 men with BMI > 33 kg/m² were followed through a 14 week residential weight loss program. The participants provided semen samples and had blood samples drawn, filled in questionnaires, and had clinical examinations before and after the intervention. Conventional semen characteristics as well as sperm DNA integrity, analysed by the sperm chromatin structure assay (SCSA) were obtained. Serum levels of testosterone, estradiol, sex hormone-binding globulin (SHBG), luteinizing hormone (LH), follicle-stimulating hormone (FSH), anti-Müllerian hormone (AMH) and inhibin B (Inh-B) were measured.

Results

Participants were from 20 to 59 years of age (median = 32) with BMI ranging from 33 to 61 kg/m². At baseline, after adjustment for potential confounders, BMI was inversely associated with sperm concentration (p = 0.02), total sperm count (p = 0.02), sperm morphology (p = 0.04), and motile sperm (p = 0.005) as well as testosterone (p = 0.04) and Inh-B (p = 0.04) and positively associated to estradiol (p < 0.005). The median (range) percentage weight loss after the intervention was 15% (3.5 - 25.4). Weight loss was associated with an increase in total sperm count (p = 0.02), semen volume (p = 0.04), testosterone (p = 0.02), SHBG (p = 0.03) and AMH (p = 0.02). The group with the largest weight loss had a statistically significant increase in total sperm count [193 millions (95% CI: 45; 341)] and normal sperm morphology [4% (95% CI: 1; 7)].

Conclusion

This study found obesity to be associated with poor semen quality and altered reproductive hormonal profile. Weight loss may potentially lead to improvement in semen quality. Whether the improvement is a result of the reduction in body weight per se or improved lifestyles remains unknown.

Inhibin B and anti-Müllerian hormone in spermatic vein of subfertile men with varicocele

INTRODUCTION

The pathophysiology of subfertility in men with varicocele remains unclear as well as the role of inhibin B (Inh-B) and anti-Müllerian hormone (AMH). The aim of this study was to evaluate Inh-B and AMH concentrations in the spermatic vein of subfertile men with varicocele.

PATIENTS AND METHODS

A total of 61 subfertile men with varicocele and 31 fertile controls underwent standard andrological evaluation. All subfertile men underwent varicocelectomy, during which blood samples were obtained from the spermatic vein to evaluate Inh-B and AMH concentrations.

RESULTS

Peripheral vein Inh-B concentrations in men with varicocele were lower as compared to controls (52.9 [8.3-136.0) vs 116±9.7 ng/dL, P = .001). There was no difference in AMH concentrations (10.2 [4.4-45.4]) vs 10.4±0.8 pg/dL, P = 0.9). Spermatic vein Inh-B concentrations in men with varicocele were higher compared to those of peripheral vein (87.6±4.4 vs 52.9 [8.3-136.0] ng/dL, P = .001). On the contrary, spermatic vein AMH concentrations were lower compared to those from peripheral vein (8.84 [3.9-47.7] vs 10.2 [4.4-45.4] pg/dL, P = .013).

CONCLUSIONS

Inh-B constitutes a reliable marker of Sertoli cell function as well as spermatogenesis. On the contrary, the clinical significance of AMH in men with varicocele remains to be elucidated.

Development of a second generation Inhibin B ELISA

Inhibins are heterodimeric protein hormones secreted by the granulosa cells of the ovary in the female and the Sertoli cells of the testis in the male. Published research studies have assessed Inhibin B levels in Sertoli cell function, ovarian reserve and granulosa cell tumors. A two-step sandwich-type enzymatic microplate assay to measure Inhibin B levels within 3.5h is reported, and sample pre-treatment is not required. The assay measures Inhibin B in 50 μL of serum or Li-Hep plasma sample against Inhibin B calibrators (10-1000 pg/mL). The highly characterized antibody pair used in the assay measures 100% Inhibin B and no response was detected above the sensitivity of the assay with Inhibin A, Activin A, Activin B, Activin AB, AMH, FSH, LH or Follistatin 315 at the concentrations tested. The second generation Inhibin B assay was compared against two commercially available assays using 60 male and 60 female samples, ranging in age from 20 to 50 years. The assay showed significant positive linear correlations to Oxford Brooks Innovation (OBI) and Diagnostics Systems Laboratories (DSL) assays (r=0.99; P<0.0001; and r=0.97; P<0.0001), respectively. Method comparison to OBI and DSL resulted in the following slope and intercept (Gen II=1.03 OBI-6.77 pg/mL and Gen II=1.57 DSL+11.29 pg/mL), respectively. Matched serum and Li-Hep plasma samples (n=120) showed a correlation coefficient of >0.99 and a slope of 0.97 with zero intercept. Total imprecision calculated on three samples and two controls over 40 runs, three replicates per run, using NCCLS EP5-A guidelines was 6.8% at 19.34 pg/mL, 4.4% at 76.03 pg/mL, 4.3% at 275.3 pg/mL, 5.4% at 99.88 pg/mL, and 5.7% at 363.9 pg/mL. The LoQ for the assay at 20% CV was 4.8 pg/mL. Dilution and spiking studies showed an average recovery of 90-110%. A highly specific, sensitive, simplified and reproducible microplate Inhibin B assay has been developed to measure Inhibin B in serum and Li-Hep plasma. The performance of the assay is ideal for investigation into the physiologic role of Inhibin B in both men and women.

The effect of obesity on sperm disorders and male infertility

The results of several studies point to an increased likelihood of abnormal semen parameters among overweight men, and an elevated risk for subfertility among couples in which the male partner is obese. Obesity is, therefore, associated with a higher incidence of male factor infertility. Several mechanisms might account for the effect of obesity on male infertility, both directly and indirectly, by inducing sleep apnea, alterations in hormonal profiles (reduced inhibin B and androgen levels accompanied by elevated estrogen levels) and increased scrotal temperatures, ultimately manifesting as impaired semen parameters (decreased total sperm count, concentration and motility; increased DNA fragmentation index). Neither the reversibility of obesity-associated male infertility with weight loss nor effective therapeutic interventions have been studied in-depth. The increasing prevalence of obesity calls for greater clinical awareness of its effects on fertility, better understanding of underlying mechanisms, and exploration into avenues of treatment.

Kisspeptin-54 at high doses acutely induces testicular degeneration in adult male rats via central mechanisms

BACKGROUND AND PURPOSE

The kisspeptins are critical regulators of reproduction and a therapeutic target for reproductive disease. Intracerebroventricular (i.c.v.) or peripheral injection of kisspeptin potently stimulates the hypothalamic-pituitary gonadal (HPG) axis via gonadotrophin-releasing hormone (GnRH). However, little is known regarding the effects of kisspeptin administration on testicular function. We investigated the mechanism(s) of kisspeptin-induced testicular degeneration in the rat.

EXPERIMENTAL APPROACH

Kisspeptin-54 (50 nmol.day(-1)) was continuously administered subcutaneously (6 h to 3 days) to male Wistar rats and reproductive hormones and testicular histology analysed. We also investigated the effects of a single subcutaneous injection of 0.5, 5 or 50 nmol kisspeptin-54. In order to determine whether the testicular degeneration observed is peripherally or centrally mediated, we investigated effects of i.c.v. injections of 5 nmol kisspeptin-54 and pre-administered a GnRH-receptor antagonist (cetrorelix) to rats peripherally treated with kisspeptin-54.

KEY RESULTS

Continuous subcutaneous administration of kisspeptin-54 caused testicular degeneration after only 12 h, when gonadotrophins were still markedly raised, suggesting that the degeneration is independent of the desensitization of the HPG axis to kisspeptin-54. Furthermore, a single subcutaneous injection of kisspeptin-54 caused dose-dependent testicular degeneration. Continuous kisspeptin-54 administration is thus not required to cause testicular degeneration. Pretreatment with cetrorelix blocked kisspeptin-induced testicular degeneration, and a single i.c.v. injection of kisspeptin-54 caused testicular degeneration, suggesting it is GnRH-mediated.

CONCLUSIONS AND IMPLICATIONS

Kisspeptin-induced testicular degeneration appears to be centrally mediated, and result from acute hyper-stimulation of the HPG axis. Doses must be carefully considered if kisspeptin is to be used therapeutically.

Effect of childhood cancer treatment on fertility markers in adult male long-term survivors

BACKGROUND

Although it is accepted that pediatric cancer treatment harbors a risk of gonadal damage, large cohort studies using up-to-date fertility markers are lacking.

PROCEDURE

The aim of our study was to evaluate the gonadal toxicity of childhood cancer treatment using fertility markers. We included 248 adult male long-term survivors of childhood cancer. Median age at diagnosis: 5 years, median age at follow-up: 24 years, median follow-up time 18 years. We evaluated patient characteristics, treatment modalities, testicular size, and endocrinological parameters including Inhibin B, luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone.

RESULTS

The median value of Inhibin B in the cancer survivor group was 126 ng/L versus 177 ng/L in the control group (P < 0.001). In the survivors, 67% had Inhibin B levels below the normal reference value of 150 ng/L compared with 26% in the control group (P < 0.05). Inhibin B was the most sensitive discriminator between survivors and controls. Significantly decreased Inhibin B levels and increased FSH levels were found in men treated for Hodgkin and non-Hodgkin lymphoma, acute-myeloid leukemia, neuroblastoma, and sarcoma as compared to other malignancies. Cumulative dosages of procarbazine and cyclophosphamide were the only independent chemotherapy-related predictors for decrease of Inhibin B levels and increase of FSH. Age at time of treatment did not influence post-treatment Inhibin B or FSH levels.

CONCLUSIONS

Severe gonadal impairment is a risk in a considerable subgroup of childhood cancer survivors based on current fertility markers like Inhibin B. Males receiving gonadotoxic treatment before puberty are not protected from post treatment gonadal dysfunction.

Diminished paternity and gonadal function with increasing obesity in men

OBJECTIVE

To examine the relationship of male obesity and reproductive function.

DESIGN

Observational study.

SETTING

Academic medical center.

PATIENT(S)

Eighty-seven adult men, body mass index (BMI) range from 16.1 to 47.0 kg/m(2) (mean = 29.3 kg/m(2); SD = 6.5 kg/m(2)).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Reproductive history, physical examination, inhibin B, FSH, LH, T, and unbound T levels, and semen analysis.

RESULT(S)

Body mass index was negatively correlated with testosterone (r = -0.38), FSH (r = -0.22), and inhibin B levels (r = -0.21) and was positively correlated with E(2) levels (r = 0.34). Testosterone also negatively correlated with skinfold thickness (r = -0.30). There was no correlation of BMI or skinfold thickness with semen analysis parameters (sperm density, volume, motility, or morphology). Inhibin B level correlated significantly with sperm motility (r = 0.23). Men with paternity had lower BMIs (28.0 kg/m(2) vs. 31.6 kg/m(2)) and lower skinfold thickness (24.7 mm vs. 34.1 mm) than men without.

CONCLUSION(S)

Obesity is an infertility factor in otherwise normal men. Obese men demonstrate a relative hypogonadotropic hypogonadism. Reduced inhibin B levels and diminished paternity suggest compromised reproductive capacity in this population.

Does ifosfamide affect gonadal function?

BACKGROUND

Gonadal dysfunction and infertility are potential late effects of cancer therapy. Ifosfamide, an alkylating agent structurally related to cyclophosphamide, is thought to cause gonadal dysfunction, though there is little published evidence.

PROCEDURE

Patients treated on sarcoma protocols containing ifosfamide as the only potential gonadotoxic agent, were evaluated, assessing pubertal development, menstrual history in the females and semen analysis in males. Biochemical evaluation included measurement of gonadotrophins, inhibin B and anti-mullerian hormone (AMH).

RESULTS

All 32 males progressed normally through puberty. No gonadal dysfunction was seen at a total ifosfamide dose of <60 g/m(2). In those with a dose >60 g/m(2), two-thirds of those who underwent semen analysis were subfertile, 31% had elevated FSH and 50% showed decreased inhibin B supporting evidence of germ cell failure. All 13 females progressed through puberty normally and had regular menses. Biochemical results were in line with published data except for AMH levels, which were lower compared with an age-matched reference group. Nine patients not recruited into the study were known to have had 11 live births.

CONCLUSIONS

Males appear more susceptible than females to ifosfamide gonadotoxicity. There may be a dose in males below which the risk of subfertility is low. In females there is preliminary evidence of reduction in ovarian reserve as measured by AMH levels, which may potentially lead to an early menopause and a reduction in the window of fertility.

Chronic subcutaneous administration of kisspeptin-54 causes testicular degeneration in adult male rats

The kisspeptins are KiSS-1 gene-derived peptides that signal through the G protein-coupled receptor-54 (GPR54) and have recently been shown to be critical regulators of reproduction. Acute intracerebroventricular or peripheral administration of kisspeptin stimulates the hypothalamic-pituitary-gonadal (HPG) axis. This effect is thought to be mediated via the hypothalamic gonadotropin-releasing hormone (GnRH) system. Chronic administration of GnRH agonists paradoxically suppresses the HPG axis after an initial agonistic stimulation. We investigated the effects of continuous peripheral kisspeptin administration in male rats by use of Alzet minipumps. Initially we compared the effects of acute subcutaneous administration of kisspeptin-10, -14, and -54 on the HPG axis. Kisspeptin-54 produced the greatest increase in plasma LH and total testosterone at 60 min postinjection and was used in the subsequent continuous administration experiments. Chronic subcutaneous long-term administration of 50 nmol kisspeptin-54/day for 13 days decreased testicular weight. Histological examination showed degeneration of the seminiferous tubules associated with a significant decrease in the circulating levels of the testes-derived hormone, inhibin B. Plasma free and total testosterone were also lower, although these changes did not reach statistical significance. Further studies examined the effects of shorter periods of continuous kisspeptin administration. Subcutaneous administration of 50 nmol kisspeptin-54 for 1 day increased plasma LH and testosterone. This effect was lost after 2 days of administration, suggesting a downregulation of the HPG axis response to kisspeptin following continuous administration. These findings indicate that kisspeptin may provide a novel tool for the manipulation of the HPG axis and spermatogenesis.

The relationship between reproductive outcome measures in DDT exposed malaria vector control workers: a cross-sectional study

BACKGROUND

The utility of blood reproductive endocrine biomarkers for assessing or estimating semen quality was explored.

METHODS

A cross-sectional study of 47 DDT exposed malaria vector control workers was performed. Tests included blood basal and post gonadotrophin releasing hormone (GnRH), luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone, sex hormone binding globulin (SHBG), estradiol (E2) and inhibin; a questionnaire (demographics and general medical history); a physical examination and semen analysis. Semen parameters were determined using either/or or both WHO or the strict Tygerberg criteria. Relationships between semen parameters and endocrine measures were adjusted for age, duration of abstinence before sampling, presence of physical abnormalities and fever in the last two months. All relationships between specific endocrine hormones were adjusted for age and basal SHBG.

RESULTS

Multiple logistic regression showed a consistent positive relationship (prevalence odds ratio (POR) = 8.2, CI:1.4-49.2) between low basal inhibin (< 100 pg/ml) and low semen count (< 40 million) and density (< 20 million/ml); consistent positive, but weaker relationships (1 > POR < 2) between abnormally low semen count as well as density and baseline and post GnRH FSH; and positive relationships (POR = 37, CI:2-655) between the prevalence of high basal estradiol (> 50 pg/ml) and abnormal morphology (proportion < 5%) and low motility (proportion < 50%). Most of the expected physiological relationships between specific endocrines were significant.

CONCLUSION

The study has demonstrated that low basal inhibin, elevated basal FSH and high basal E2 can serve as markers of impaired semen quality.

Does folic acid and zinc sulphate intervention affect endocrine parameters and sperm characteristics in men?

We evaluated pre- and post-intervention endocrine and semen parameters in a double-blind, placebo-controlled intervention study to investigate the underlying mechanism of increased sperm concentration after folic acid and zinc sulphate intervention. A total of 47 fertile and 40 subfertile males participated in a 26-week intervention study consisting of a daily treatment with folic acid (5 mg/day) and zinc sulphate (66 mg/day), or placebo. Pre- and post-intervention semen parameters, serum folate, zinc, follicle-stimulating hormone (FSH), testosterone and inhibin B concentrations were measured. The results indicated that intervention treatment significantly increased sperm concentration in subfertile males. Other semen and endocrine parameters were not affected by intervention treatment. At baseline, positive correlations were found between serum zinc and sperm concentration, motility and inhibin B. Serum zinc and FSH were inversely correlated. As (already) well known from previous research, inhibin B positively correlated with sperm concentration, motility and morphology, and was inversely correlated with FSH. The latter was positively correlated with testosterone. In addition, testosterone and inhibin B were inversely correlated. After intervention, the correlations with zinc disappeared. We conclude that the increase in sperm concentration after folic acid and zinc sulphate intervention is not the result of alterations in FSH, testosterone or inhibin B concentrations. Although zinc and folate have several effects on spermatogenesis, the underlying mechanisms involved are not clear.

Serum inhibin B and follicle-stimulating hormone levels as markers in the evaluation of azoospermic men: a comparison

Inhibin B is a glycoprotein hormone produced mainly by Sertoli cells of the testes in the adult male. It selectively suppresses the secretion of pituitary follicle-stimulating hormone (FSH) and has local paracrine actions in the testes. Its measurement is useful for investigating the role of inhibin B in male gonadal dysfunction. The objective of this study was to investigate the efficacy of serum inhibin B in men with nonobstructive azoospermia in comparison with FSH. Serum concentration of FSH was measured using microparticle enzyme immunoassay, inhibin B by specific solid phase sandwich enzyme-linked immunosorbent assay in men with nonobstructive azoospermia (n = 46) and control fertile men (n = 5). Mean inhibin B and FSH level was 104.6 pg ml(-1) and 4.0 mIU ml(-1) in control men whereas the value for nonobstructive azoospermic men was 17.06 pg ml(-1) and 31.1 mIU ml(-1) respectively. Inhibin B and FSH levels were significantly different in azoospermia than controls (P < 0.0001). There were six cases of nonobstructive azoospermia with normal inhibin B. Testicular histology did not find any evidence of spermatogenesis in three cases with normal inhibin B. This demonstrated that inhibin B was not a superior predictor for testicular function in our study.