Quantitative trait analysis suggests polymorphisms of estrogen-related genes regulate human sperm concentrations and motility

Microcystin-LR Induces Estrogenic Effects at Environmentally Relevant Concentration in Black-Spotted Pond Frogs (Pelophylax nigromaculatus): In Situ, In Vivo, In Vitro, and In Silico Investigations

Harmful cyanobacterial blooms are frequent and intense worldwide, creating hazards for aquatic biodiversity. The potential estrogen-like effect of Microcystin-LR (MC-LR) is a growing concern. In this study, we assessed the estrogenic potency of MC-LR in black-spotted frogs through combined field and laboratory approaches. In 13 bloom areas of Zhejiang province, China, the MC-LR concentrations in water ranged from 0.87 to 8.77 μg/L and were correlated with sex hormone profiles in frogs, suggesting possible estrogenic activity of MC-LR. Tadpoles exposed to 1 μg/L, an environmentally relevant concentration, displayed a female-biased sex ratio relative to controls. Transcriptomic results revealed that MC-LR induces numerous and complex effects on gene expression across multiple endocrine axes. In addition, exposure of male adults significantly increased the estradiol (E2)/testosterone (T) ratio by 3.5-fold relative to controls. Downregulation of genes related to male reproductive endocrine function was also identified. We also showed how MC-LR enhances the expression of specific estrogen receptor (ER) proteins, which induce estrogenic effects by activating the ER pathway and hypothalamic-pituitary-gonadal (HPG) axis. In aggregate, our results reveal multiple lines of evidence demonstrating that, for amphibians, MC-LR is an estrogenic endocrine disruptor at environmentally relevant concentrations. The data presented here support the need for a shift in the MC-LR risk assessment. While hepatoxicity has historically been the focus of MC-LR risk assessments, our data clearly demonstrate that estrogenicity is a major mode of toxicity at environmental levels and that estrogenic effects should be considered for risk assessments on MC-LR going forward.

Polymorphisms in the HSF2, LRRC6, MEIG1 and PTIP genes correlate with sperm motility in idiopathic infertility

The aim of this study was to investigate the association of 24 functionally important single nucleotide polymorphisms (SNPs) with male infertility. In this cross-sectional study, we genotyped 24 functionally important single nucleotide polymorphisms in 24 infertility candidate genes in 500 oligo-/astheno-/oligoastheno-/normo-zoospermic infertile men with idiopathic infertility. Sequenom iPlex gold assay was used for genotyping. Sperm count and motility were compared between prevalent genotypes at each test locus. We did not observe any significant difference in the average sperm count between the alternate genotypes for the loci in the KLK3, LRRC6, MEIG1, HSF2, ESR2 and PTIP genes. However, we observed a significant difference in sperm motility between the alternate genotypes for the loci in the LRRC6, MEIG1, HSF2 and PTIP genes. Polymorphisms in the LRRC6 (rs200321595), MEIG1 (rs150031795), HSF2 (rs143986686) and PTIP (rs61752013) genes show association with sperm motility.

Effects of MCLR exposure on sex hormone synthesis and reproduction-related genes expression of testis in male Rana nigromaculata

Microcystin-leucine-arginine (MCLR) is the most popular and toxic variant among microcystins, which can cause severe reproductive toxicity to animals. However, the mechanisms of reproductive toxicity induced by MCLR in amphibians are still not entirely clear. In the current study, toxicity mechanisms of MCLR on the reproductive system of male Rana nigromaculata followed by low concentration (0, 0.1, 1, and 10 μg/L) and short-term (0, 7, and 14 days) MCLR exposure were shown. It was observed that MCLR could be bioaccumulated in the testes of male frogs, and the theoretical bioaccumulation factor values were 0.24 and 0.19 exposed to 1 μg/L and 10 μg/L MCLR for 14 days, respectively. MCLR exposure significantly decreased testosterone (T) concentrations and increased estradiol (E2) concentrations exposed to 1 and 10 μg/L MCLR for 14 days. The mRNA levels of HSD17B3 were downregulated, and HSD17B1 and CYP19A1 mRNA expression levels were upregulated, respectively. Only 10 μg/L MCLR group showed significant induction of follicle-stimulating hormone (FSH) levels and cyclic adenosine monophosphate (cAMP) content. Moreover, AR and ESR1 mRNA expression levels were significantly upregulated exposed to 1 and 10 μg/L MCLR for 14 days, respectively. Our results suggested that low-concentration MCLR induced transcription changes of CYP19A1, HSD17B3, and HSD17B1 led to endocrine disorders, and caused interference of spermatogenesis by the decrease of T and abnormal gene expressions of AR and ESR1 in the testes of R. nigromaculata.

Interactions between oestrogen and 1α,25(OH)2-vitamin D3 signalling and their roles in spermatogenesis and spermatozoa functions

Oestrogens and 1α,25(OH)₂-vitamin D₃ (1,25-D₃) are steroids that can provide effects by binding to their receptors localised in the cytoplasm and in the nucleus or the plasma membrane respectively inducing genomic and non-genomic effects. As confirmed notably by invalidation of the genes, coding for their receptors as tested with mice with in vivo and in vitro treatments, oestrogens and 1,25-D₃ are regulators of spermatogenesis. Moreover, some functions of ejaculated spermatozoa as viability, DNA integrity, motility, capacitation, acrosome reaction and fertilizing ability are targets for these hormones. The studies conducted on their mechanisms of action, even though not completely elicited, have allowed the demonstration of putative interactions between their signalling pathways that are worth examining more closely. The present review focuses on the elements regulated by oestrogens and 1,25-D₃ in the testis and spermatozoa as well as the interactions between the signalling pathways of both hormones.

Genetics of Sex Hormone-Binding Globulin and Testosterone Levels in Fertile and Infertile Men of Reproductive Age

Context

Testosterone (T) is a central androgenic hormone, and sex hormone-binding globulin (SHBG) is the major determinant of its bioactivity. There are no acknowledged genetic variants with clear-cut clinical implications, modulating T levels in men.

Objective

To confirm genetic associations of top loci (SHBG, GCKR, SLCO1B1, and JMJD1C) from genome-wide association (GWA) studies for serum SHBG and T.

Design Patients

Groups differing in general and reproductive parameters: young men (n = 540; 19.3 ± 1.8 years), severe idiopathic male infertility patients (n = 641; 31.6 ± 6.0 years), and male partners of pregnant women (n = 324; 31.9 ± 6.6 years). All patients were recruited at the Andrology Centre, Tartu University Hospital, Estonia.

Main Outcome Measures

Genetic associations with reproductive hormones, testicular and sperm parameters (linear regression, additive model); intergroup allele/genotype distribution comparisons.

Results

Associations with serum SHBG levels were robust for SHBG -68 G>A [rs1799941; meta-analysis: P = 3.7 × 10^-14; allelic effect (standard error) = 4.67 (0.62) nmol/L], SHBG +1091 C>T [rs727428; P = 7.3 × 10^-11; -3.74 (0.57)], SHBG Pro185Leu [rs6258; P = 1.2 × 10^-4, -12.2 (3.17)], and GCKR Pro446Leu [rs1260326; P = 1.5 × 10^-4; -2.2 (0.59)]. Measured T concentrations correlated with genetically modulated levels of SHBG (r = 0.48 to 0.74, P < 0.0001), guaranteeing stable availability of free T. Among infertile men, SHBG Pro185Leu substitution showed additional downstream effect on luteinizing hormone [P = 5.1 × 10^-5; -1.66 (0.57) IU/L] and follicle-stimulating hormone [P = 3.4 × 10^-3; -2.48 (1.23) IU/L]. No associations with male reproductive parameters were detected for SHBG Asp327Asn (rs6259), SLCO1B1 Val174Ala (rs4149056), and JMJD1C intronic variant rs7910927.

Conclusions

Claims were replicated and additional associations were detected for four of seven tested GWAS top loci. Perspective clinical investigations of these variants are hypotestosteronemia among aging men and pharmacogenetics of hormone replacement therapy.

Hormone-Based Treatments in Subfertile Males

Subfertility is defined as the condition of being less than normally fertile though still capable of effecting fertilization. When these subfertile couples seek assistance for conception, a thorough evaluation of male endocrine function is often overlooked. Spermatogenesis is a complex process where even subtle alterations in this process can lead to subfertility or infertility. Male endocrine abnormalities may suggest a specific diagnosis contributing to subfertility; however, in many patients, the underlying etiology is still unknown. Optimizing underlying endocrine abnormalities may improve spermatogenesis and fertility. This manuscript reviews reproductive endocrine abnormalities and hormone-based treatments.

CYP1A1 3801T>C polymorphism implicated in altered xenobiotic metabolism is not associated with variations in sperm production and function as measured by total motile sperm and fertilization rates with intracytoplasmic sperm injection

OBJECTIVE

To evaluate the cytochrome P450 3801T>C polymorphism's frequency in relation to semen production, as determined by semen analysis parameters, and sperm function, as determined by fertilization rates with intracytoplasmic sperm injection (ICSI).

DESIGN

Case-control study.

SETTING

Academic-affiliated private practice.

PATIENT(S)

This study included patients undergoing IVF from 2004 to 2014 grouped into categories based on semen analysis parameters performed at a single andrology laboratory. Cases were patients with total motile sperm (TMS) counts of ≤20 × 10(6). Frequency-matched controls were selected with TMS of >20 × 10(6).

INTERVENTION(S)

The 3801T>C polymorphism was identified using DNA from serum samples with real-time quantitative polymerase chain reaction.

MAIN OUTCOME MEASURE(S)

CYP1A1 3801T>C polymorphism frequency in TMS groups and distribution in fertilization rate outcomes with ICSI.

RESULT(S)

A total of 460 cases were identified with ≤20 × 10(6) TMS, and 489 age-matched controls with >20 × 10(6) TMS were selected across the study time frame. For those with <5 × 10(6) vs. >20 × 10(6) TMS there was no difference when comparing heterozygous (odds ratio [OR] 0.96; 95% confidence interval [CI] 0.66-1.40) or homozygous mutant (OR 1.33; 95% CI 0.52-3.20) with the wild-type patients. Additionally, no difference was seen when analyzing subgroups <5 × 10(6), 5-20 × 10(6), and >20 × 10(6) TMS in a similar fashion. Receiver operating characteristic (ROC) curve analysis did not find a significant TMS count based on presence of the polymorphism (area under the ROC curve = 0.51). There were 460 patients who underwent IVF/ICSI, and fertilization rates did not differ with presence of the polymorphism (area under the ROC curve = 0.50).

CONCLUSION(S)

Allele frequency of the 3801T>C polymorphism does not correlate with semen production as determined by TMS counts or sperm function as determined by fertilization rates with ICSI. The use of neither semen analysis parameters nor fertilization rates with ICSI helps identify CYP1A1 polymorphism carriers.

Evidence for association of the rs605059 polymorphism of HSD17B1 gene with recurrent spontaneous abortions

OBJECTIVE

To investigate whether the missense rs605059 polymorphism of HSD17B1 gene, which is expressed mainly in the placenta, is associated with recurrent spontaneous abortions (RSA).

METHODS

This study group consisted of 138 women with three or more unexplained spontaneous abortions, before the 20th week of gestation, with the same partner, while 140 healthy women served as controls. To genotype the individuals, we used the polymerase chain reaction-restriction fragment length polymorphism method.

RESULTS

The genotyping of the rs605059 polymorphism revealed the frequencies 0.22, 0.45 and 0.33, for AA, GA and GG genotypes, respectively, for the patient group and 0.37, 0.41 and 0.22, respectively, for the control group. The A allele frequencies were 0.44 and 0.57 for the patient and control group, respectively, and the G allele frequencies were 0.56 and 0.43 for the patient and control group, respectively. Statistical analysis of the results indicated the existence of significant differences in genotype and allele frequencies between the two groups.

CONCLUSION

The rs605059 polymorphism of the HSD17B1 gene is associated with increased risk of RSA in our Caucasian Greek population. Thus it could be used as a prognostic genetic marker for RSA.

Screening of a panel of steroid-related genes showed polymorphisms of aromatase genes confer susceptibility to advanced stage endometriosis in the Taiwanese Han population

OBJECTIVE

To establish a multilocus model for studying the effect of steroid-related genes on advanced stage endometriosis.

MATERIALS AND METHODS

A total of 121 patients with advanced stage endometriosis and 171 control women were included. Eighteen single-nucleotide polymorphisms (SNPs) from nine genes (HSD17B1, HSD17B2, HSD17B5, HSD17B6, CYP17, CYP19, ERα, ERβ, and PGR) were genotyped using the TaqMan assays. Logistic regression models were used to evaluate the genetic effects, with adjustment for other covariates.

RESULTS

Only the presence of the mutant CYP19 (aromatase gene) was associated with a significantly increased risk of endometriosis after adjusting for age, BMI, and parity (p = 0.002, OR = 2.69; 95% CI = 1.44-5.02). No association was ascertained between the other investigated SNPs and endometriosis.

CONCLUSION

Polymorphisms of the aromatase gene confer susceptibility to advanced stage endometriosis in the Taiwanese Han population.

Genome-wide association study for sperm concentration in Holstein-Friesian bulls

The aim of the study was to screen the entire bull genome to identify markers and candidate genes underlying sperm concentration. The analysed data set originates from a population of 877 Polish Holstein-Friesian bulls. Based on sperm concentration value, two extreme groups of bulls were created: Low (L, n = 126) and High (H, n = 140). Each bull was genotyped using the Illumina BovineSNP50 BeadChip. Genome-wide association analysis was performed with the use of GoldenHelix SVS7 software. An additive model with a Cohran-Armitage test, Correlation/Trend adjusted by a Bonferroni test, was used to estimate the effect of SNP marker for sperm concentration. Thirteen markers reached genome-wide significance. The most significant SNPs were located on chromosome 3 (rs109154964 and rs108965556), 14 (rs41621145) and 18 (rs41615539), in the close vicinity of protein arginine methyltransferase 6 (PRMT6), Sel1 repeat containing 1 (SELRC1), triple QxxK/R motif containing (TRIQK) and zinc finger homeobox 3 (ZFHX3) genes, respectively. For three other candidate genes located close to significant markers (within a distance of ca 1 Mb), namely histone deacetylase 9 (HDAC9), an inhibitor of DNA binding 2 (ID2) and glutathione S-transferase theta 1 (GSTT1), their potential role in the production of male germ cells was confirmed in earlier studies. Six additional candidate genes (Vav3, GSTM1, CDK5, NOS3, PDP1 and GAL3ST1) were suspected of being significantly associated with sperm concentration or semen biochemistry. Our results indicate the genetic complexity of sperm concentration but also open the possibility for finding causal polymorphism useful in marker-assisted selection.

Synergistic effect of fadrozole and insulin-like growth factor-I on female-to-male sex reversal and body weight of broiler chicks

The aim of this study was to investigate the effects of Fadrozole hydrochloride and recombinant human insulin-like growth factor I (rhIGF-I) on female-to-male sex reversal, hatching traits, and body weight of broiler chickens. On the third day of incubation, fertile eggs were randomly assigned to five experimental groups comprising (i) Fadrozole (0.1 mg/egg), (ii) rhIGF-I (100 ng/egg), (iii) Fadrozole (0.1 mg/egg) + rhIGF-I (100 ng/egg), (iv) vehicle injection (10 mM acetic acid and 0.1% BSA), and (v) non-injected eggs. Eggs in the rhIGF-I-injected groups showed the mode of hatching time at the 480th hour of incubation, 12 hours earlier compared to the other groups, with no statistically significant difference in mortality and hatchability. On Day 1 and 42 of production, 90% of genetically female chicks were masculinized using Fadrozole treatment, while 100% female-to-male phenotypic sex reversal was observed in the Fadrozole+rhIGF-I group. Fadrozole equalized the body weight of both genders, although rhIGF-I was effective on the body weight of male chicks only. Interestingly, combined rhIGF-I and Fadrozole could increase the body weight in both sexes compared to the individual injections (P<0.05). These findings revealed that (i) IGF-I-treated chicken embryos were shown to be an effective option for overcoming the very long chicken deprivation period, (ii) the simultaneous treatment with Fadrozole and IGF-I could maximize the female-to-male sex reversal chance, (iii) the increase in the body weight of masculinized chickens via Fadrozole could be equal to their genetically male counterparts, and (iv) the IGF-I effectiveness, specifically along with the application of aromatase inhibitors in female chicks, indicates that estrogen synthesis could be a stumbling block for the IGF-I action mechanism in female embryos.

Clinical genetic testing for male factor infertility: current applications and future directions

Spermatogenesis involves the aggregated action of up to 2300 genes, any of which, could, potentially, provide targets for diagnostic tests of male factor infertility. Contrary to the previously proposed common variant hypothesis for common diseases such as male infertility, genome-wide association studies and targeted gene sequencing in cohorts of infertile men have identified only a few gene polymorphisms that are associated with male infertility. Unfortunately, the search for genetic variants associated with male infertility is further hampered by the lack of viable animal models of human spermatogenesis, difficulty in robustly phenotyping infertile men and the complexity of pedigree studies in male factor infertility. In this review, we describe basic genetic principles involved in understanding the genetic basis of male infertility and examine the utility and proper clinical use of the proven genetic assays of male factor infertility, specifically Y chromosome microdeletions, chromosomal translocations, karyotype, cystic fibrosis transmembrane conductance regulator mutation analysis and sperm genetic tests. Unfortunately, these tests are only able to diagnose the cause of about 20% of male factor infertility. The remainder of the review will be devoted to examining novel tests and diagnostic tools that have the potential to explain the other 80% of male factor infertility that is currently classified as idiopathic. Those tests include epigenetic analysis of the spermatozoa and the evaluation of rare genetic variants and copy number variations in patients. Success in advancing to the implementation of such areas is not only dependent on technological advances in the laboratory, but also improved phenotyping in the clinic.

Meta-analysis of the association of oestrogen receptor-beta gene RsaI (G/A) and AluI (A/G) polymorphisms with male infertility

A more precise assessment of association of oestrogen receptor-beta genes RsaI(G/A) and AluI(A/G) polymorphisms with male infertility from current contradictory results is the aim of this meta-analysis including five RsaI and six AluI studies respectively. No association was observed between infertility and RsaI or AluI. In the stratified analysis by ethnicity, increased risk was found among Caucasians with GA versus GG (OR = 2.263, 95% CI = 1.073-4.776, I(2)  = 57.1%) and dominant model (OR = 2.117, 95% CI = 1.018-4.403, I(2)  = 49.0%) of RsaI. It was not observed for AluI. In the stratified analysis by infertility subtypes, a reduced risk in GA of AluI was observed among azoospermia or severe oligospermia (GA versus AA: OR = 0.686, 95% CI = 0.498-0.945, I(2)  = 21.2%; recessive model: OR = 1.403, 95% CI = 1.056-1.864, I(2)  = 31.7%), and reduced risk was in recessive model (OR = 0.650, 95% CI = 0.446-0.948, I(2)  = 0.0%) of subtypes, except for azoospermia or severe oligospermia. However, this finding was not observed in RsaI. The meta-analysis showed GA and GG of AluI are possibly resistant factors for spermatogenesis dysfunction and deteriorated sperm quality.

Association between 3801T>C polymorphism of CYP1A1 and idiopathic male infertility risk: a systematic review and meta-analysis

BACKGROUND

Epidemiological studies have evaluated the association between 3801T>C polymorphism of CYP1A1 gene and the risk for idiopathic male infertility, but the results are inconclusive. We aimed to derive a more precise estimation of the relationship by conducting a meta-analysis of case-control studies.

METHODS

This study conformed to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. PubMed, Embase and CNKI databases were searched through November 2013 to identify relevant studies. Pooled odds ratios with 95% confidence intervals were used to assess the strength of the association between CYP1A1 3801T>C polymorphism and idiopathic male infertility risk. Q-test was performed to evaluate between-study heterogeneity and publication bias was appraised using funnel plots. Sensitivity analyses were conducted to evaluate the robustness of meta-analysis findings.

RESULTS

Six studies involving 1,060 cases and 1,225 controls were included in this meta-analysis. Overall, significant associations between 3801T>C polymorphism and idiopathic male infertility risk were observed in allelic comparison (OR = 1.36, 95% CI: 1.01-1.83), homozygous model (OR = 2.18, 95% CI: 1.15-4.12), and recessive model (OR = 1.86, 95% CI: 1.09-3.20), with robust findings according to sensitivity analyses. However, subgroup analyses did not further identify the susceptibility to idiopathic male infertility in all comparisons. Funnel plot inspections did not reveal evidence of publication bias.

CONCLUSIONS

The current meta-analysis provides evidence of a significant association between CYP1A1 3801T>C polymorphism and idiopathic male infertility risk. Considering the limitation inherited from the eligible studies, further confirmation in large-scale and well-designed studies is needed.

Characterization of the testicular, epididymal and endocrine phenotypes in the Leuven Vdr-deficient mouse model: targeting estrogen signalling

Vitamin D is a key factor for calcium and bone homeostasis, but signalling through the vitamin D receptor (VDR) seems also to be important for testicular function. To test the functional role of vitamin D signalling we examined the male reproductive system of the Leuven Vdr-ablated (Vdr(-/-)) mice, previously established as a model for hereditary vitamin D-resistant rickets. We investigated reproductive hormones, changes in gene expression and histological phenotype of eleven Vdr(-/-), eight Vdr(+/-) and nine Vdr(+/+) mice. Testicular and epididymal histology were grossly normal in Vdr(-/-) mice. Accordingly, no differences were found in serum concentrations of testosterone, estradiol, LH, and FSH or testicular expression of Cyp19a1, Ersα, Cyp17a1, Star, Insl3, Inhbb, and Amh. However, a significantly lower ERβ expression was found in testis of Vdr(+/-) and Vdr(-/-) mice, conversely epididymal expressions of ERα and the estrogen-target gene Aqp9 were higher. In conclusion, vitamin D seems dispensable for murine spermatogenesis and sex hormone production, but aberrant estrogen-signalling may elicit some of the VDR-mediated effects on male reproduction.

Oestrogen receptor alpha gene polymorphisms relationship with semen variables in infertile men

This study aimed to assess the association of oestrogen receptor alpha (ER-α) gene polymorphisms and semen variables in infertile oligoasthenoteratozoospermic (OAT) men. In all, 141 men were grouped into fertile men (n = 60) and infertile OAT men (n = 81). They were subjected to assessment of semen analysis, acrosin activity, serum reproductive hormones and genotyping of ER-α gene. Frequencies of p and x alleles in ER-α gene PvuII and XbaI polymorphisms were more prevalent among fertile men compared with infertile OAT men. Presence of P and X alleles was associated with increased incidence of male infertility for genotypes PP, XX compared with genotypes pp and xx (OR = 2.8; 95% CI: 2.36-6.97; P = 0.001 and OR = 4.1, 95% CI: 1.49-11.39; P = 0.001, respectively). The mean of semen variables and sperm acrosin activity were significantly higher in cases associated with pp than PP and in xx than XX genotypes of ER-α gene. Mean levels of all serum reproductive hormones demonstrated nonsignificant differences in different ER-α genotypes except oestrogen that was elevated in PP and XX ER-α gene genotypes. It is concluded that as oestrogen is concerned in male gamete maturation, ER-α gene polymorphisms might play a role in the pathophysiology of male infertility.

Glutathione S-transferases gene polymorphisms and risk of male idiopathic infertility: a systematic review and meta-analysis

The Glutathione S-transferases (GSTs) polymorphisms have been implicated in susceptibility to male idiopathic infertility, but study results are still controversial. To investigate the genetic associations between GSTs polymorphisms and risk of male idiopathic infertility, a systematic review and meta-analysis were performed. Meta-analysis was performed by pooling odds ratio (OR) with its corresponding 95 % confidence interval (95 % CI) form studies in electronic databases up to March 16, 2012. Glutathione S-transferase M 1 (GSTM1) null genotype, Glutathione S-transferase T 1 (GSTT1) null genotype, and dual null genotype of GSTM1/GSTT1 were analyzed independently. 14 eligible studies with a total of 1,845 idiopathic infertility males and 1,729 controls were included. There were 13 studies on GSTM1 polymorphism, 10 ones on GSTT1 polymorphism and 5 ones on GSTM1-GSTT1 interaction analysis. Meta-analyses of total relevant studies showed GSTM1 null genotype was significantly associated with an increased risk of male idiopathic infertility (OR = 1.40, 95 % CI 1.07-1.84, P OR = 0.015). The GSTM1-GSTT1 interaction analysis showed dual null genotype of GSTM1/GSTT1 was also significantly associated with increased risk of male idiopathic infertility (OR = 1.85, 95 % CI 1.07-3.21, P OR = 0.028). Subgroup analyses by ethnicity showed the associations above were still statistically significant in Caucasians (For GSTM1, OR = 1.51, 95 % CI 1.11-2.05, P OR = 0.009; For GSTM1/GSTT1, OR = 2.10, 95 % CI 1.51-2.91, P OR < 0.001). This meta-analysis suggests GSTM1 null genotype contributes to increased risk of male idiopathic infertility in Caucasians, and males with dual null genotype of GSTM1/GSTT1 are particularly susceptible to developing idiopathic infertility.

Effect of quercetin, rutin, naringenin and epicatechin on lipid peroxidation induced in human sperm

Quercetin, rutin, naringenin, epicatechin are flavonoids with diverse properties, including antioxidant potential. We evaluated, in vitro, the cytotoxicity of these flavonoids (20, 30, 50, 100, 200, 400 μM) in swim-up selected human sperm. Antioxidant activity was tested against tert-butylhydroperoxide induced lipid peroxidation using a C11-BODIPY(581/591) probe and transmission electron microscopy. A significant concentration-dependent effect on sperm viability (P<0.001) and motility (P<0.001) was observed. Lipid peroxidation was decreased in samples treated with 30 μM quercetin (P<0.01) and 30 μM rutin (P<0.05) versus samples incubated with tert-butylhydroperoxide alone. Naringenin (50-100 μM) showed a low protective effect and epicatechin (200 μM) was not efficacious. Transmission electron microscopy analysis confirmed the protective action of rutin and in particular quercetin on damages induced by lipid peroxidation. These results underlined the antioxidant properties of quercetin and rutin. A possible role of these compounds in the supplementation of media used during semen handling warrants attention and further studies.

Evolving utility of sex hormone-binding globulin measurements in clinical medicine

PURPOSE OF REVIEW

Sex hormone-binding globulin (SHBG) regulates the plasma levels and biological actions of the sex steroids: testosterone and estradiol. Advances in our understanding of how plasma SHBG levels are determined, and how SHBG functions, have provided insight into how SHBG should be used to assess the actions of its sex-steroid ligands, and as a biomarker of metabolic and endocrine abnormalities.

RECENT FINDINGS

Plasma SHBG levels fluctuate throughout life in response to the changes in metabolic and physiologic states, and are altered by natural hormones and synthetic steroids. Interindividual differences in plasma SHBG levels and activity are also influenced by polymorphisms within the structural and regulatory regions of the SHBG gene.

SUMMARY

Measurements of SHBG are widely used to predict plasma free testosterone levels in patients suffering from excess androgen exposures, but have broader utility in assessing the risk for endocrine diseases and clinical sequelae of the metabolic syndrome, namely, type 2 diabetes and cardiovascular disease. It is anticipated that new genetic and functional data regarding SHBG will reveal whether SHBG is simply a biomarker of these diseases or participants in their cause.

GSTM1 null genotype contributes to increased risk of male infertility: a meta-analysis

BACKGROUND

Many studies have investigated the association between Glutathione S-Transferase M 1 (GSTM1) null genotype and risk of male infertility, but the impact of GSTM1 null genotype on infertility risk is unclear owing to the obvious inconsistency among those studies. This study aimed to quantify the strength of association between GSTM1 null genotype and risk of male infertility.

METHODS

We searched the PubMed, Embase and Wangfang databases for studies investigating the association between GSTM1 null genotype and risk of male infertility. We estimated pooled odds ratio (OR) with its 95 % confidence interval (95 % CI) to assess this possible association.

RESULTS

Twelve case-control studies with 1, 589 infertility cases and 1, 537 controls were included. Meta-analysis of total 12 studies showed that GSTM1 null genotype was associated with increased risk of male infertility (OR = 1.34, 95%CI 1.02-1.77, P = 0.036). In subgroup analysis of Caucasians, there was also an obvious association between GSTM1 null genotype and increased risk of male infertility (OR = 1.51, 95%CI 1.11-2.05, P = 0.006). Sensitivity analyses by sequential omission of individual studies or omitting studies without high quality did not significantly alter the overall pooled OR. Cumulative meta-analysis further showed a trend of more obvious association as information accumulated. No evidence of publication bias was observed.

CONCLUSION

Meta-analyses of available data suggest that GSTM1 null genotype contributes to increased risk of male infertility.

Polymorphisms in CYP1B1 modify the risk of idiopathic male infertility with abnormal semen quality

BACKGROUND

It is acknowledged that Cytochrome P450 1B1 (CYP1B1) plays a crucial role in metabolism and is involved in lots of diseases. We carried out this study to evaluate the association between CYP1B1 single nucleotide polymorphisms (SNPs) and male infertility in the Han-Chinese population with abnormal semen parameters.

METHODS

We genotyped five CYP1B1 polymorphisms by using TaqMan allelic discrimination assay and Genome Lab SNP-stream. A total of 591 idiopathic infertile men and 419 fertile controls were comprised in the research. Semen quality analysis was performed using computer assisted sperm analysis. According to semen parameters, we divided cases into 3 subgroups in the stratified analysis.

RESULTS

In our study, we only found genetic variant rs1056836 is correlated with idiopathic male infertility (P=0.012). Additionally, in strategy analysis, rs1056836 may decrease the risk of abnormal sperm motility (OR=0.11, 95% CI=0.01, 0.86). While other four variants showed no significant association with male infertility.

CONCLUSIONS

Our results suggested that polymorphism of CYP1B1 modified the risk of male infertility, and men harboring this polymorphism had lower risk of abnormal sperm parameters. These findings should be validated by more epidemiological and functional studies.