No abstract

The endocrine disruptor bis(2-ethylhexyl) phthalate (DEHP) has been shown to exert adverse effects on the male animal reproductive system. However, its mode of action is unclear and a systematic analysis of its molecular targets is needed. In the present study, we investigated the effects of prenatal exposure to 300 mg/kg/day DEHP during a critical period for gonads differentiation to testes on male mice offspring reproductive parameters, including the genome-wide RNA expression and associated promoter methylation status in the sperm of the first filial generation. It was observed that adult male offspring displayed symptoms similar to the human testicular dysgenesis syndrome. A combination of sperm transcriptome and methylome data analysis allowed to detect a long-lasting DEHP-induced and robust promoter methylation-associated silencing of almost the entire cluster of the seminal vesicle secretory proteins and antigen genes, which are known to play a fundamental role in sperm physiology. It also resulted in the detection of a DEHP-induced promoter demethylation associated with an up-regulation of three genes apparently not relevant for sperm physiology and partially related to the immune system. As previously reported, DEHP induced an increase in mir-615 microRNA expression and a genome-wide decrease in microRNA promoter methylation. A functional analysis revealed DEHP-induced enrichments in down-regulated gene transcripts coding for peroxisome proliferator-activated receptors and tumor necrosis factor signaling pathways, and in up-regulated gene transcripts coding for calcium binding and numerous myosin proteins. All these enriched pathways and networks have been described to be associated in some way with the reproductive system. This study identifies a large new array of genes dysregulated by DEHP that may play a role in the complex system controlling the development of the male reproductive system.

Background Sperm counts have been steadily decreasing over the past five decades with regional differences in the Western world. The reasons behind these trends are complex, but numerous insights indicate that environmental and lifestyle factors are important players. Objective To evaluate semen quality and male reproductive health in Switzerland. Materials and methods A nationwide cross‐sectional study was conducted on 2523 young men coming from all regions of Switzerland, recruited during military conscription. Semen volume, sperm concentration, motility, and morphology were analyzed. Anatomy of the genital area and testicular volume was recorded. Testicular cancer incidence rates in the general population were retrieved from Swiss regional registries. Results Median sperm concentration adjusted for period of sexual abstinence was 48 million/mL. Comparing with the 5th percentile of the WHO reference values for fertile men, 17% of men had sperm concentration below 15 million/mL, 25% had less than 40% motile spermatozoa, and 43% had less than 4% normal forms. Disparities in semen quality among geographic regions, urbanization rates, and linguistic areas were limited. A larger proportion of men with poor semen quality had been exposed in utero to maternal smoking. Furthermore, testicular cancer incidence rates in the Swiss general population increased significantly between 1980 and 2014. Discussion For the first time, a systematic sampling among young men has confirmed that semen quality is affected on a national level. The median sperm concentration measured is among the lowest observed in Europe. No specific geographical differences could be identified. Further studies are needed to determine to what extent the fertility of Swiss men is compromised and to evaluate the impact of environmental and lifestyle factors. Conclusion A significant proportion of Swiss young men display suboptimal semen quality with only 38% having sperm concentration, motility, and morphology values that met WHO semen reference criteria.

STUDY QUESTION Do selective serotonin reuptake inhibitor (SSRI) antidepressants affect the function of human sperm? SUMMARY ANSWER The SSRI antidepressant Sertraline (e.g. Zoloft) inhibits the sperm-specific Ca2+ channel CatSper and affects human sperm function in vitro. WHAT IS KNOWN ALREADY In human sperm, CatSper translates changes of the chemical microenvironment into changes of the intracellular Ca2+ concentration ([Ca2+]i) and swimming behavior. CatSper is promiscuously activated by oviductal ligands, but also by synthetic chemicals that might disturb the fertilization process. It is well known that SSRIs have off-target actions on Ca2+, Na+ and K+ channels in somatic cells. Whether SSRIs affect the activity of CatSper is, however, unknown. STUDY DESIGN, SIZE, DURATION We studied the action of the seven drugs belonging to the most commonly prescribed class of antidepressants, SSRIs, on resting [Ca2+]i and Ca2+ influx via CatSper in human sperm. The SSRI Sertraline was selected for in-depth analysis of its action on steroid-, prostaglandin-, pH- and voltage-activation of human CatSper. Moreover, the action of Sertraline on sperm acrosomal exocytosis and penetration into viscous media was evaluated. PARTICIPANTS/MATERIALS, SETTING, METHODS The activity of CatSper was investigated in sperm of healthy volunteers, using kinetic Ca2+ fluorimetry and patch-clamp recordings. Acrosomal exocytosis was investigated using Pisum sativum agglutinin and image cytometry. Sperm penetration in viscous media was evaluated using the Kremer test. MAIN RESULTS AND THE ROLE OF CHANCE Several SSRIs affected [Ca2+]i and attenuated ligand-induced Ca2+ influx via CatSper. In particular, the SSRI Sertraline almost completely suppressed Ca2+ influx via CatSper. Remarkably, the drug was about four-fold more potent to suppress prostaglandin- versus steroid-induced Ca2+ influx. Sertraline also suppressed alkaline- and voltage-activation of CatSper, indicating that the drug directly inhibits the channel. Finally, Sertraline impaired ligand-induced acrosome reaction and sperm penetration into viscous media. LIMITATIONS, REASONS FOR CAUTION This is an in vitro study. Future studies have to assess the physiological relevance in vivo. WIDER IMPLICATIONS OF THE FINDINGS The off-target action of Sertraline on CatSper in human sperm might impair the fertilization process. In a research setting, Sertraline may be used to selectively inhibit prostaglandin-induced Ca2+ influx. STUDY FUNDING/COMPETING INTEREST(S) This work was supported by the Swiss Centre for Applied Human Toxicology (SCAHT), the Département de l’Instruction Publique of the State of Geneva, the German Research Foundation (CRU326), the Interdisciplinary Center for Clinical Research, Münster (IZKF; Str/014/21), the Innovation Fund Denmark (grant numbers 14-2013-4) and the EDMaRC research grant from the Kirsten and Freddy Johansen’s Foundation. The authors declare that no conflict of interest could be perceived as prejudicing the impartiality of the research reported. TRIAL REGISTRATION NUMBER NA.

No abstract