Genetic variation in leptin and leptin receptor genes as a risk factor for idiopathic male infertility

Leptin Receptor Gln223Arg Polymorphism of Human Spermatozoa Associated with Male Infertility in a Chinese Population

Background

Leptin (LEP) is believed to play a crucial role in male reproduction, while the molecular mechanisms through which LEP affects the male reproductive system are unclear. LEP acts by binding to a leptin receptor (LEPR) which mediates its physiological action, but there are only limited studies on the function of LEPR in human sperm.

Purpose

This study aimed to determine the Gln223Arg polymorphisms of the LEPR gene in human spermatozoa and evaluate their possible relationship with semen variables.

Methods

The study was performed on Chinese men: 115 healthy subjects and 108 patients with primary and 98 with secondary infertility. Semen samples were obtained from all patients, and semen variables were analyzed. The genotypic and allelic frequencies of Gln223Arg polymorphism in spermatozoa were determined by PCR and restriction fragment length polymorphism (RFLP) analyses. Statistical analyses were performed using the chi-square test, the Kruskal-Wallis test, and the Mann-Whitney test.

Results

There were no significant differences in genotypic or allelic frequency distributions of Gln223Arg polymorphism among men with primary infertility, secondary infertility, and controls. Similarly, semen volume and sperm concentration did not differ with the different genotypes in all groups of men. The percentages of motile sperm for AA + AG genotypes in men with primary infertility (31.98%) were significantly lower than those in secondary infertility, and control men with GG genotypes were 34.41% and 59.36%, respectively. At the same time, the percentages of normal morphology sperm for AA + AG genotypes in men with primary infertility (2.93%) were significantly lower than those in secondary infertility and control men with GG genotypes 3.71% and 6.54%, respectively.

Conclusion

This study reveals a possible association between the Gln223Arg polymorphism of the LEPR gene in spermatozoa affecting spermatozoal membrane integrity and having a direct role in sperm motility.

X-ray micro-computed tomography in the assessment of penile cavernous fibrosis in a rabbit castration model

BACKGROUND

Current assessment methods of penile cavernous fibrosis in animal models have limitations due to the inability to provide complex and volume analysis of fibrotic alterations.

OBJECTIVE

The aim was to evaluate micro-computed tomography (micro-CT) for assessment of cavernous fibrosis and compare it with histological, histochemical, immunohistochemical, and RT-PCR analysis.

MATERIALS AND METHODS

A controlled trial was performed involving 25 New Zealand male rabbits with induced testosterone deficiency by orchidectomy. Penile samples were obtained before and after 7, 14, 21, 84 days from orchidectomy. We consistently performed: a) gray value analysis of corpora cavernosa 3D models reconstructed after micro-CT; b) morphometry of smooth muscles/connective tissue ratio, collagen type I/III ratio, and area of TGF-beta-1 expression in corpora cavernosa; c) RT-PCR of TGF-beta-1 expression.

RESULTS

Micro-CT allowed visualization of penile structures at the resolution comparable to light microscopy. Gray values of corpora cavernosa decreased from 1673 (1512-1773) on the initial day to 1184 (1089-1232) on 21 day (p < 0,005); however, on 84 day, it increased to 1610 (1551-1768). At 21 and 84 days, there were observed a significant decrease in smooth muscle/connective tissue ratio and a significant increase in collagen type I/III ratio (p < 0,05). TGF-beta1 expression increased on 84 day according to immunohistochemistry (p < 0,005). RT-PCR was impossible to conduct due to the absence of RNA in obtained samples after micro-CT.

DISCUSSION AND CONCLUSIONS

Micro-CT provided 3D visualization of entire corpora cavernosa and assessment of radiodensity alterations by gray value analysis in fibrosis progression. We speculate that gray value changes at early and late fibrosis stages could be related to tissue reorganization. RT-PCR is impossible to conduct on tissue samples studied by micro-CT due to RNA destruction. We also suggest that micro-CT could negatively affect the immunohistochemical outcome, as a significant increase of TGF-beta-1 expression occurs later than histological fibrotic signs. This article is protected by copyright. All rights reserved.

Genes predisposing to syndromic and nonsyndromic infertility: a narrative review

Background

Advanced biological techniques have helped produce more insightful findings on the genetic etiology of infertility that may lead to better management of the condition. This review provides an update on genes predisposing to syndromic and nonsyndromic infertility.

Main body

The review identified 65 genes linked with infertility and infertility-related disorders. These genes regulate fertility. However, mutational loss of the functions of the genes predisposes to infertility. Twenty-three (23) genes representing 35% were linked with syndromic infertility, while 42 genes (65%) cause nonsyndromic infertility. Of the 42 nonsyndromic genes, 26 predispose to spermatogenic failure and sperm morphological abnormalities, 11 cause ovarian failures, and 5 cause sex reversal and puberty delay. Overall, 31 genes (48%) predispose to male infertility, 15 genes (23%) cause female infertility, and 19 genes (29%) predispose to both. The common feature of male infertility was spermatogenic failure and sperm morphology abnormalities, while ovarian failure has been the most frequently reported among infertile females. The mechanisms leading to these pathologies are gene-specific, which, if targeted in the affected, may lead to improved treatment.

Conclusions

Mutational loss of the functions of some genes involved in the development and maintenance of fertility may predispose to syndromic or nonsyndromic infertility via gene-specific mechanisms. A treatment procedure that targets the affected gene(s) in individuals expressing infertility may lead to improved treatment.

Biological Network Model of Effect of Chronic Intermittent Hypoxia on Spermatogenesis in Rats

Background

The aim of this study was to explore the effect of obstructive sleep apnea hypopnea syndrome (OSAHS) on spermatogenesis and the effects of the expression of related proteins.

Material/Methods

Rats in Group A were normoxic (exposed to a normal level of oxygen). Rats in Group B were exposed to intermittent hypoxia. After 6 weeks, the rats were killed and their epididymides were removed. The epididymis of one testis was used to test indices of semen quality. The epididymis of the other testis was stained with hematoxylin & eosin to observe pathologic changes in the testis. We used real-time quantitative polymerase chain reaction (RT-qPCR) and Western blotting to measure expression of the protein and mRNA of leptin, Janus kinase (JAK), and signal transducer and activator of transcription (STAT) in rat testicular cells. Cytoscape v3.7.1 was employed to construct the OSAHS–male infertility network and protein–protein interactions network. Information on common targets of OSAHS and male infertility was imported into the Database for Annotation, Visualization and Integrated Discovery (DAVID). Then, analyses of pathway enrichment were undertaken using the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes databases.

Results

Data were obtained 6 weeks after completion of OSAHS modeling. Compared with Group A, the total sperm count and sperm motility in Group B showed a downward trend (P<0.05). Staining showed no obvious abnormality in Group A. However, numerous structurally abnormal spermatogenic tubules were observed in Group B samples, and the lumen was atrophied and thinned, arranged unevenly, and the gap between the tubules was markedly increased. Western blotting and RT-qPCR showed that, compared with Group A, expression of the protein and mRNA of leptin, JAK, and STAT in the testes of rats in Group B was significantly increased (P<0.05 for all).

Conclusions

These data suggest that: (1) Chronic intermittent hypoxia can cause pathologic damage to rat testes; (2) Oligozoospermia was highly correlated and regulated by the JAK2/STAT6 signaling pathway; and (3) Chronic intermittent hypoxia can lead to decreased spermatogenesis in rats.

Association between leptin, obesity, hormonal interplay and male infertility

Male infertility is a major health problem worldwide. We investigated a possible association between leptin, obesity, hormonal interplay and male infertility. This cross-sectional study of 313 males (178 infertile and 135 fertile) was carried out in 2017. The subjects were categorised by body mass index (BMI) and body fat percentage (BF%) into normal weight, overweight and obese. Significantly higher levels of BMI and BF% (p-value < 0.001) and lower levels of FSH, LH, testosterone, and SHBG (p-value < 0.001) were found in infertile males. However, no significant difference was observed in leptin levels (p-value = 0.35). Leptin levels were significantly higher, and all the sex hormones were significantly lower (p-value < 0.001) in obese subjects, whereas according to BF% only leptin, FSH and SHBG were significantly different. Leptin showed a significant positive correlation with BMI and BF% (p < 0.001). A strong positive link to serum testosterone was found with age, FSH, and LH (p < 0.001) and a negative one with BMI and BF% (p < 0.001). In mutivariable anlaysis, after adjusting for the other covariates, a significant association between FSH and testosterone (p-value <0.001) was found. Serum leptin levels did not differ significantly in fertile and infertile groups, and no association was found with infertility. Furthermore, male obesity was found to be associated with infertility with the decrease in levels of sex hormones.