Loa Nordkap

Obesity and Bariatric Surgery Drive Epigenetic Variation of Spermatozoa in Humans.

Obesity is a heritable disorder, with children of obese fathers at higher risk of developing obesity. Environmental factors epigenetically influence somatic tissues, but the contribution of these factors to the establishment of epigenetic patterns in human gametes is unknown. Here, we hypothesized that weight loss remodels the epigenetic signature of spermatozoa in human obesity. Comprehensive profiling of the epigenome of sperm from lean and obese men showed similar histone positioning, but small non-coding RNA expression and DNA methylation patterns were markedly different. In a separate cohort of morbidly obese men, surgery-induced weight loss was associated with a dramatic remodeling of sperm DNA methylation, notably at genetic locations implicated in the central control of appetite. Our data provide evidence that the epigenome of human spermatozoa dynamically changes under environmental pressure and offers insight into how obesity may propagate metabolic dysfunction to the next generation.

REGIONAL DIFFERENCES AND TEMPORAL TRENDS IN MALE REPRODUCTIVE HEALTH DISORDERS: SEMEN QUALITY MAY BE A SENSITIVE MARKER OF ENVIRONMENTAL EXPOSURES

The decline in semen quality has been the subject of an animated debate. A recent prospective study now irrefutably shows a decline in semen quality in men from Finland, a country that previously boasted good semen quality. Semen quality has, in some countries, reached a level where a considerable fraction of young men are at risk of fertility problems. Impaired semen quality, testicular cancer, cryptorchidism and hypospadias are risk factors for each other, and the testicular dysgenesis syndrome (TDS) has been put forward to explain the observations. This syndrome implies that the four disease entities share the same patho-physiological etiology caused by disturbed testicular development in early fetal life. It seems likely that the rapid rise in TDS-associated conditions can, at least partly, be explained by environmental factors. Animal studies provide strong evidence that manmade chemicals can disrupt the hormone dependent pathways responsible for fetal gonadal development, subsequently leading to TDS-like symptoms. In humans, fetal exposure to endocrine disrupting substances may play a role, although genetic factors are probably also involved. Recent studies indicate that exposure to endocrine disrupters also in adulthood may affect semen quality and reproductive hormones. Causal relationships are inherently difficult to establish in humans, and a clear connection between the disorders and specific toxicants has not been established. It seems likely that the cumulative effects of various low-dose exposures to endocrine disrupters in our environment are responsible for the adverse effects in the male reproductive system. Semen quality may be the most sensitive marker of adverse environmental exposures, and we suggest that standardized surveillance studies of semen quality are continued or initiated to monitor the combined effects of various preventive actions.

Association Between Use of Marijuana and Male Reproductive Hormones and Semen Quality: A Study Among 1,215 Healthy Young Men

A total of 1,215 young Danish men aged 18-28 years were recruited between 2008 and 2012 when they attended a compulsory medical examination to determine their fitness for military service. The participants delivered a semen sample, had a blood sample drawn, and underwent a physical examination. They responded to questionnaires including information on marijuana and recreational drug use during the past 3 months (no use, use once per week or less, or use more than once per week). A total of 45% had smoked marijuana within the last 3 months. Regular marijuana smoking more than once per week was associated with a 28% (95% confidence interval (CI): -48, -1) lower sperm concentration and a 29% (95% CI: -46, -1) lower total sperm count after adjustment for confounders. The combined use of marijuana more than once per week and other recreational drugs reduced the sperm concentration by 52% (95% CI: -68, -27) and total sperm count by 55% (95% CI: -71, -31). Marijuana smokers had higher levels of testosterone within the same range as cigarette smokers. Our findings are of public interest as marijuana use is common and may be contributing to recent reports of poor semen quality.

Psychological stress and testicular function: a cross-sectional study of 1,215 Danish men

OBJECTIVE To study the associations between self-reported psychological stress, semen quality, and serum reproductive hormones among young Danish men. DESIGN Cross-sectional study. SETTING University hospital-based research center. PARTICIPANT(S) Danish men (median age 19 years) from the general population were investigated from 2008 to 2012. INTERVENTION(S) Participants completed a questionnaire on health and lifestyle, including a four-item questionnaire about self-rated stress, had a physical examination performed, delivered a semen sample, and had a blood sample drawn. MAIN OUTCOME MEASURE(S) Semen parameters (semen volume, sperm concentration, and percentages of motile and morphologically normal spermatozoa) and serum levels of reproductive hormones (LH, FSH, T, calculated free T, sex hormone-binding globulin, and inhibin B). RESULT(S) Poorer semen quality was detected among men with self-reported stress scores above an intermediate stress level, in a dose-response manner. For example, men with the highest stress levels had 38% (95% confidence interval [CI] 3%; 61%) lower sperm concentration, 34% (95% CI 59%; 106%) lower total sperm count, and 15% (95% CI 1%; 27%) lower semen volume than men with intermediate stress levels. No significant associations between self-reported stress and levels of reproductive hormones were detected. CONCLUSION(S) A negative association between self-reported stress and semen quality was detected. If causal, stress may be a contributing factor for suboptimal semen quality among otherwise healthy men.

Vitamin D deficiency and low ionized calcium are linked with semen quality and sex steroid levels in infertile men

STUDY QUESTION Are low vitamin D levels linked with semen quality and sex steroids in infertile men? SUMMARY ANSWER Infertile men with vitamin D deficiency had lower sperm motility, total numbers of motile sperm, Inhibin B, sex-hormone-binding-globulin (SHBG) and testosterone/estradiol ratio, but higher levels of free sex steroids, than infertile men with normal vitamin D levels. WHAT IS KNOWN ALREADY Low vitamin D levels have been associated with decreased sperm motility in healthy men, but a relationship between vitamin D and calcium with semen quality and especially sex steroids has not been sufficiently described in infertile men. STUDY DESIGN, SIZE, DURATION This study comprises baseline characteristics of 1427 infertile men screened from 2011 to 2014 for inclusion in a randomized clinical trial, the Copenhagen-Bone-Gonadal Study. PARTICIPANTS/MATERIALS, SETTING, METHODS In total 1427 infertile men, consecutively referred to our tertiary andrological centre for fertility workup, underwent a physical examination and had semen quality assessed based on two samples and blood analysed for serum testosterone, SHBG, estradiol, inhibin B, luteinizing hormone, follicle-stimulating hormone (FSH), 25-hydroxyvitamin D (25-OHD), ionized calcium (Ca(2+)) and karyotype. There were 179 men excluded due to serious comorbidities or anabolic steroid usage, leaving 1248 patients for analyses. MAIN RESULTS AND THE ROLE OF CHANCE Men with 25-OHD >75 nmol/l had higher sperm motility and 66 and 111% higher total numbers of motile spermatozoa after 45 and 262 min, respectively, than men with 25-OHD <25 nmol/l (all P < 0.05). SHBG levels and testosterone/estradiol ratios were 15 and 14% lower, respectively, while free testosterone and estradiol ratios were 6 and 13% higher, respectively, in men with 25-OHD <25 nmol/l (all P < 0.05). Men with lower Ca(2+) levels had higher progressive sperm motility and inhibin B/FSH ratio but lower testosterone/estradiol ratio (all P < 0.05). LIMITATIONS, REASONS FOR CAUTION All outcomes presented are predefined end-points but inferral of causality is compromised by the descriptive study design. It remains to be shown whether the links between vitamin D, calcium, semen quality and sex steroids in infertile men are causal. WIDER IMPLICATIONS OF THE FINDINGS The associations between vitamin D deficiency and low calcium with semen quality and sex steroids support the existence of a cross-link between regulators of calcium homeostasis and gonadal function in infertile men. STUDY FUNDING/COMPETING INTERESTS This study was supported by the Danish Agency for Science, Technology and Innovation, Hørslev Fonden, Danish Cancer Society and Novo Nordisk Foundation. There are no conflicts of interest. TRIAL REGISTRATION NUMBER NCT01304927. DATE OF TRIAL REGISTRATION 25 February 2011. DATE OF ENROLMENT OF FIRST PATIENT 8 March 2011.

Is Sedentary Lifestyle Associated With Testicular Function? A Cross-Sectional Study of 1,210 Men

Based on cross-sectional data on 1,210 healthy young Danish men, we investigated whether sedentary lifestyle was associated with testicular function (semen quality and reproductive hormones) independent of physical activity. The men were invited to participate in the study between 2008 and 2012, when they attended a compulsory medical examination to determine their fitness for military service. Information on sedentary behavior (television watching and computer time) and physical activity was obtained by questionnaire. The men had a physical examination, delivered a semen sample, and had a blood sample drawn. Time spent watching television, but not time sitting in front of a computer, was associated with lower sperm counts. Men who watched television more than 5 hours/day had an adjusted sperm concentration of 37 million/mL (95% confidence interval (CI): 30, 44) versus 52 million/mL (95% CI: 43, 62) among men who did not watch television; total sperm counts in those 2 groups were 104 million (95% CI: 84, 126) and 158 million (95% CI: 130, 189), respectively. Furthermore, an increase in follicle-stimulating hormone and decreases in testosterone and the testosterone/luteinizing hormone ratio were detected in men watching many hours of television. Self-rated physical fitness, but not time spent on physical activity, was positively associated with sperm counts.

Dynamic GnRH and hCG testing: establishment of new diagnostic reference levels

OBJECTIVE Gonadotropin-releasing hormone (GnRH) and human chorionic gonadotropin (hCG) stimulation tests may be used to evaluate the pituitary and testicular capacity. Our aim was to evaluate changes in follicular-stimulating hormone (FSH), luteinizing hormone (LH) and testosterone after GnRH and hCG stimulation in healthy men and assess the impact of six single nucleotide polymorphisms on the responses. DESIGN GnRH and hCG stimulation tests were performed on 77 healthy men, 18-40 years (reference group) at a specialized andrology referral center at a university hospital. The potential influence of the tests was illustrated by results from 45 patients suspected of disordered hypothalamic-pituitary-gonadal axis. METHODS Baseline, stimulated, relative and absolute changes in serum FSH and LH were determined by ultrasensitive TRIFMA, and testosterone was determined by LC-MS/MS. RESULTS For the reference group, LH and FSH increased almost 400% and 40% during GnRH testing, stimulated levels varied from 4.4 to 58.8 U/L and 0.2 to 11.8 U/L and FSH decreased in nine men. Testosterone increased approximately 110% (range: 18.7-67.6 nmol/L) during hCG testing. None of the polymorphisms had any major impact on the test results. Results from GnRH and hCG tests in patients compared with the reference group showed that the stimulated level and absolute increase in LH showed superior identification of patients compared with the relative increase, and the absolute change in testosterone was superior in identifying men with Leydig cell insufficiency, compared with the relative increase. CONCLUSIONS We provide novel reference ranges for GnRH and hCG test in healthy men, which allows future diagnostic evaluation of hypothalamic-pituitary-gonadal disorders in men.

Self-reported onset of puberty and subsequent semen quality and reproductive hormones in healthy young men

STUDY QUESTION Is there an association between pubertal onset and subsequent reproductive health in young men? SUMMARY ANSWER Self-reported later onset of puberty was associated with reduced semen quality and altered serum levels of reproductive hormones among 1068 healthy, young Danish men. WHAT IS KNOWN ALREADY The long-term effects of variations in the onset of male puberty on subsequent reproduction remain largely unstudied. STUDY DESIGN, SIZE, DURATION In a cross-sectional study, young healthy Danish men were approached when they attended a compulsory medical examination to determine their fitness for military service from 2008 to 2012. PARTICIPANTS/MATERIALS, SETTINGS, METHODS A total of 1068 healthy, young Danish men (mean age 19 years) participated. They were asked to assess whether onset of penile and testicular growth, development of pubic hair and voice break occurred earlier, at the same time as or later than their peers. Their semen quality (semen volume, sperm concentration, total sperm count and percentages of motile and morphologically normal spermatozoa) and serum concentrations of sex hormones (LH, FSH, total testosterone, SHBG, inhibin B) and testicular size were determined. MAIN RESULTS AND THE ROLE OF CHANCE The response rate was 29%. Of the 1068 men who then participated, 652 answered the questions about penile growth and pubic hair development and were therefore included in the analysis. Self-reported later onset of puberty was associated with a 25% reduction in sperm concentration (95% CI -41%; -4%), a 40% reduction in total sperm count (-55%; -21%), a 1.6% age point reduction in morphological normal spermatozoa (-2.9; -0.3) and a 1.6 ml reduction in testicular size (-2.4 and -0.8 ml), after adjustment for confounders. Self-reported later onset of puberty was also associated with a 9% (3%; 15%) reduction in free testosterone and a 16% (2%; 31%) increase in FSH, after adjustment for confounders. LIMITATIONS, REASON FOR CAUTION Our study was cross-sectional and reverse causality cannot be ruled out. In addition, we cannot rule out the possibility that the men with late puberty onset had not yet fully matured although most were in Tanner stage 5. WIDER IMPLICATIONS OF THE FINDINGS Approximately 15% of young Danish men have self-reported later onset of puberty than their peers. We found poorer testicular function in young men with a history of later pubertal development, suggesting that timing of pubertal onset may be a fundamental marker of male reproductive health. However, we cannot exclude the possibility that these men had not fully matured at the time of examination and therefore their semen quality may yet improve, which makes follow-up important. STUDY FUNDING/COMPETING INTERESTS This work was supported by the Danish Council for Strategic Research, Program Commission on Health, Food and Welfare (project number 2101-08-0058), Rigshospitalet (grants 961506336 and R42-A1326), European Union, DEER (grant agreement no 212844), the Danish Ministry of Health and the Danish Environmental Protection Agency and Kirsten and Freddy Johansens Foundation (grant 95-103-72087). There are no competing interests.

Possible involvement of the glucocorticoid receptor (NR3C1) and selected NR3C1 gene variants in regulation of human testicular function

Perceived stress has been associated with decreased semen quality but the mechanisms have not been elucidated. It is not known whether cortisol, the major stress hormone in humans, can act directly via receptors in the testis, and whether variants in the gene encoding the glucocorticoid receptor (NR3C1) can possibly modulate the effect. To address these questions, we investigated the expression of the glucocorticoid receptor in human testicular tissue, including adult and fetal samples (n = 20) by immunohistochemical staining, and in silico analysis of publicly available datasets. In the adult testis NR3C1 protein was detected in peritubular cells, a subset of Leydig cells, Sertoli cells (weak), and spermatogonia, but not in spermatids. The NR3C1 expression pattern in fetal testis samples differed by a notably stronger reaction in Sertoli cells, lack of staining in gonocytes but the presence in a subset of pro‐spermatogonia, and the almost absent reaction in nascent peritubular cells. In parallel, we explored the association between adult testicular function and three single nucleotide NR3C1 polymorphisms (BcII [rs41423247], 9β [rs6198], and Tth111I [rs10052957]) affecting glucocorticoid sensitivity. Testicular function was determined by semen analysis and reproductive hormone profiling in 893 men from the general population. The NR3C1 SNP BclI was associated with semen quality in an over‐dominant manner with heterozygotes having better semen parameters compared to both homozygote constellations, and with sperm motility showing the strongest association. This association was supported by a higher inhibin B and inhibin B/FSH ratio, as well as a lower FSH in BclI heterozygotes. The SNPs 9β and Tth111I were not associated with semen parameters. Although the clinical impact of the findings is limited, the results substantiate a suggested link between stress and testicular function. Hence this investigation should be regarded as a discovery study generating hypotheses for future studies.

Anti-Mullerian hormone levels and fecundability in women with a natural conception

OBJECTIVES To investigate the association between anti-Müllerian hormone (AMH), a well-established marker of the ovarian reserve, and time-to-pregnancy (TTP) in natural conceptions, and to assess changes in serum-AMH in early pregnancy. STUDY DESIGN A cross sectional study comprising 279 women aged 21-42 years with a natural conception recruited during 2012-2014. AMH was measured in gestational week 10-19. AMH z-scores (z-AMH) adjusted for gestational week at blood sampling were categorised in the 1st, 2nd-4th (reference), and 5th quintile. Data were analysed by discrete-time survival-analysis and results presented as odds ratios (OR), 95% confidence interval (CI); OR <1 indicating a longer TTP and OR >1 indicating a shorter TTP. RESULTS The median AMH-level was 23.0 (range:<3.0;144.0)pmol/l, and serum-AMH decreased by 7.5% (95% CI:-12.0%;-2.8%) per gestational week. Mean±SD female age was 30.9±3.6years. The median TTP was 2 (range: 1-32) months. After adjustment for possible confounders including total sperm count, TTP was unrelated to female age (aOR:1.0, 95% CI:0.9;1.0) and continuous z-AMH (aOR:0.8, 95% CI:0.7;1.0), but women in the low z-AMH group had a shorter TTP than the reference group (aOR:1.7, 95% CI:1.1;2.7). TTP was prolonged in preconception oral contraceptive (OC) users (aOR:0.7, 95% CI:0.5;1.0, p=0.04). Compared with women having used OC <2 years, TTP was significantly longer in women having used OC for 2-12 years (aOR:0.5, 95% CI:0.2;1.0, p=0.048) and >12 years (aOR:0.4, 95% CI:0.2;0.9, p=0.022) after age-adjustment. CONCLUSIONS TTP was unrelated with z-AMH when modelled as a continuous covariate. Unexpectedly, TTP was shorter in the low z-AMH group. Natural conception was observed in women with a wide range of AMH-levels including women with undetectable serum-AMH. A continuous decrease in serum-AMH was observed during first and second trimester. Preconception OC-use was identified as an independent predictor of a prolonged TTP, and the duration of OC-use appeared to influence the delay in conception. Although this is presently one of the largest studies investigating the association between AMH and fecundability in fertile women, the study has some limitation including a relatively low participation rate and a risk of selection bias in addition to AMH assessment in pregnancy and a retrospective collection of TTP and OC-use associated with a risk of recall bias. These limitations may explain the unexpected finding of a shorter TTP in the low z-AMH group.