Smoking Induces a Decline in Semen Quality and the Activation of Stress Response Pathways in Sperm

Adverse Effects of Nicotine on Human Sperm Nuclear Proteins

The effects of smoking on human health have long been documented. However, only a few studies have highlighted the direct effects of nicotine on sperm function. Nicotine, as a chemical compound found in tobacco, has been shown to modulate different aspects of spermatogenesis and sperm functions. Nicotine can lead to a reduction in the number of sperm, their motility and functionality. It can change the molecular expressions involved in sperm function, including genes encoding sperm nuclear proteins. The most important nuclear proteins that play a critical role in sperm function are known as H2B histone family, member W, testis-specific (H2BFWT), transition protein 1 (TNP1), transition protein 2 (TNP2), protamine-1 (PRM1), and protamine-2 (PRM2). These proteins are involved in sperm chromatin condensation, which in turn affects fertilization and embryonic development. Any alteration in the expression of these genes due to nicotine exposure/usage may lead to adverse implications in couples' fertility and the health of future generations. Since research in this area is still relatively new, it underscores the importance of understanding the potential side effects of environmental factors such as nicotine on reproductive health.

Semen Quality Measures in Hookah and Cigarette Smokers Compared to Nonsmokers

Background: The relationship between smoking and human health is a well-researched and continuously evolving field. The impact of smoking on semen quality, and consequently on male fertility, has also been explored, though most studies have primarily focused on cigarette smoking rather than hookah smoking. Objective: In this study, we aimed to investigate and compare the effects of hookah and cigarette smoking on semen parameters in a sample of Jordanian males. Methods: A total of 558 participants were prospectively recruited, including 300 cigarette smokers, 95 hookah smokers, and 163 nonsmokers (control). Semen analysis was performed approximately 1 h after ejaculation following the World Health Organization guidelines (2021). Results: Interestingly, semen volume was significantly decreased in hookah smokers (p = 0.0097) but not in cigarette smokers when compared to the control group. No significant differences were observed in semen volume, progressive sperm motility, total motility, sperm count, sperm morphology (p = 0.2714, p = 0.8752, p = 0.6671, p = 8614, and p = 0.9261, respectively), and sperm vitality between hookah and cigarette smokers. Furthermore, except for semen volume, these semen parameters were not statistically different in both tested groups when compared to the control group. Conclusions: Hookah smokers demonstrated lower semen volume compared to the control group. Additionally, no significant differences were found in sperm count, percentage of sperm motility, normal forms of sperm, and sperm vitality between hookah and cigarette smokers or between these groups and the control group.

How do lifestyle and environmental factors influence the sperm epigenome? Effects on sperm fertilising ability, embryo development, and offspring health

Recent studies support the influence of paternal lifestyle and diet before conception on the health of the offspring via epigenetic inheritance through sperm DNA methylation, histone modification, and small non-coding RNA (sncRNA) expression and regulation. Smoking may induce DNA hypermethylation in genes related to anti-oxidation and insulin resistance. Paternal diet and obesity are associated with greater risks of metabolic dysfunction in offspring via epigenetic alterations in the sperm. Metabolic changes, such as high blood glucose levels and increased body weight, are commonly observed in the offspring of fathers subjected to chronic stress, in addition to an enhanced risk of depressive-like behaviour and increased sensitivity to stress in both the F0 and F1 generations. DNA methylation is correlated with alterations in sperm quality and the ability to fertilise oocytes, possibly via a differentially regulated MAKP81IP3 signalling pathway. Paternal exposure to toxic endocrine-disrupting chemicals (EDCs) is also linked to the transgenerational transmission of increased predisposition to disease, infertility, testicular disorders, obesity, and polycystic ovarian syndrome (PCOS) in females through epigenetic changes during gametogenesis. As the success of assisted reproductive technology (ART) is also affected by paternal diet, BMI, and alcohol consumption, its outcomes could be improved by modifying factors that are dependent on male lifestyle choices and environmental factors. This review discusses the importance of epigenetic signatures in sperm-including DNA methylation, histone retention, and sncRNA-for sperm functionality, early embryo development, and offspring health. We also discuss the mechanisms by which paternal lifestyle and environmental factors (obesity, smoking, EDCs, and stress) may impact the sperm epigenome.

The association between ambient temperature and semen quality in a Northern Peninsular Province, China

BACKGROUND

Extreme ambient temperature has been linked to decline in males' semen quality. Although the temperature-semen quality association has been examined in certain cities of South China, how the effect size of the extreme temperature may lag over critical windows in spermatogenesis and whether the strength of association may vary in North China have yet been adequately explored.

OBJECTIVES

To quantify the association between air temperature and semen quality, and identify critical exposure windows in a Northern Peninsular Province, China.

MATERIALS AND METHODS

Data on semen quality in 2014-2019 were collected from the Human Sperm Bank of Institute of Women, Children and Reproductive Health, Shandong University, China. Daily meteorological data (0.01°×0.01°) were assigned to each subject's residential address. The linear mixed-effect model combined with the distributed lag nonlinear model was used to estimate the effect of ambient temperature over critical spermatogenesis windows.

RESULTS

The temperature-semen quality association was inverted V-shaped, with the maximum lag being 0-45 days before ejaculation and the threshold being 9.2°C. Progressively and total motile sperm number, and total sperm number declined more substantially than other semen quality parameters. Semen quality was more sensitive to cold exposure during the epididymal storage period than the sperm motility development period. By contrast, semen quality was insensitive to heat exposure during both critical spermatogenesis windows. Impairment of certain semen quality parameters was more obvious for males with higher educational attainment and those aged over 35 years.

DISCUSSION AND CONCLUSION

Exposure to non-optimal temperature is associated with decreased semen quality in North China, with the epididymal storage and sperm motility development periods more sensitive to cold exposure than heat. Older males and those with higher educations may need particular awareness.

Empirical Treatments for Male Infertility: A Focus on Lifestyle Modifications and Medicines

BACKGROUND/OBJECTIVES

Male infertility is a prevalent issue impacting numerous couples worldwide. This review aims to evaluate the effectiveness of empirical therapies for male infertility, focusing on both lifestyle modifications and medical treatments. This study provides a comprehensive overview of interventions aimed at improving male fertility outcomes.

METHODS

A thorough review of the existing literature was conducted, encompassing studies on lifestyle changes such as dietary changes, smoking cessation, alcohol moderation, and exercise. Additionally, medical treatments including selective estrogen receptor modulators, gonadotropins, aromatase inhibitors, phosphodiesterase-5 inhibitors, antioxidants, dopamine agonists, kallikrein, indomethacin, low-dose corticosteroids, alpha-blockers, and nitric oxide donors were evaluated. The study population included males diagnosed with infertility, focusing on various underlying causes.

RESULTS

Lifestyle modifications were found to have a positive impact on sperm quality. Evidence shows that a healthy diet, smoking cessation, moderate alcohol consumption, and regular exercise improve fertility outcomes. Medical treatments demonstrated significant improvements in sperm production and quality. Selective estrogen receptor modulators and gonadotropins enhanced sperm parameters. Aromatase inhibitors and phosphodiesterase-5 inhibitors specifically improved sperm motility and increased pregnancy rates. Antioxidants, such as vitamins E and C and coenzyme Q10, reduced oxidative stress and enhanced sperm counts, motility, and morphology. Dopamine agonists, particularly cabergoline, normalized prolactin levels and improved fertility outcomes. Kallikrein therapy improved sperm parameters and increased pregnancy rates. Indomethacin treatment was associated with increased sperm concentrations and motility. Low-dose corticosteroids and alpha-blockers showed variable results, and nitric oxide donors like L-arginine enhanced sperm counts and motility.

CONCLUSIONS

Empirical therapies, including lifestyle modifications and medical treatments, significantly enhance sperm quality and reproductive potential. These integrated approaches are essential in improving fertility outcomes in males. However, further extensive randomized trials are necessary to definitively establish the most effective treatments.

Association between serum cotinine levels and urinary incontinence in adults in the United States: a population-based cross-sectional analysis

Environmental tobacco smoke (ETS) exposure has been shown to be associated with a variety of diseases, but evidence regarding the association between it and urinary incontinence (UI) is limited. Cotinine, a metabolite of nicotine in the human body, can more accurately quantify the level of human exposure to tobacco smoke. The study utilized data from seven survey cycles (2007-March 2020 Pre-pandemic) of the National Health and Nutrition Examination Survey (NHANES) program. Weighted multivariable logistic regression analysis, subgroup analysis, interaction tests, smooth curve fitting, and threshold effect models were used to analyze the relationship between serum cotinine and UI. Additionally, a 1:1 nearest neighbor propensity score matching (PSM) method was employed to minimize the impact of confounding factors. Before and after PSM, serum cotinine levels were higher in individuals with UI than those without (P < 0.05). Both before and after PSM, UI was positively correlated with serum cotinine levels, with a significantly increased risk of urinary incontinence when serum cotinine levels were in the Q3 range (before PSM: OR = 1.89, 95% CI = 1.59-2.24; after PSM: OR = 1.60, 95% CI = 1.28-2.00). Smooth curve fitting before and after PSM showed an approximate J-shaped non-linear dose-response relationship between log-transformed serum cotinine levels and UI. This study indicates that among American adults, there is a positive relationship between serum cotinine levels and UI, which is also significant in self-reported non-smoking populations. Therefore, reducing exposure to environmental tobacco smoke (e.g., avoiding second-hand smoke) in work and daily life may help alleviate the occurrence of UI, and serum cotinine levels have the potential to be a tool for predicting the degree of risk of developing UI.

Exploring altered bovine sperm trajectories by sperm tracking in unconfined conditions

Mammalian sperm motility is getting more relevant due to rising infertility rates worldwide, generating the need to improve conventional analysis and diagnostic approaches. Nowadays, computer assisted sperm analysis (CASA) technologies represent a popular alternative to manual examination which is generally performed by observing sperm motility in very confined geometries. However, under physiological conditions, sperm describe three-dimensional motility patterns which are not well reconstructed by the limited depth of standard acquisition chambers. Therefore, affordable and more versatile alternatives are needed. Here, a motility analysis in unconfined conditions is proposed. In details, the analysis is characterized by a significant longer duration -with respect to conventional systems- with the aim to observe eventually altered motility patterns. Brightfield acquisition in rectangular glass capillaries captured frozen-thawed bovine spermatozoa which were analyzed by means of a self-written tracking routine and classified in sub-populations, based on their curvilinear velocity. To test the versatility of our approach, cypermethrin -a commonly used pesticides- known to be responsible for changes in sperm motility was employed, assessing its effect at three different time-steps. Experimental results showed that such drug induces an increase in sperm velocity and progressiveness as well as circular pattern formation, likely independent of wall interactions. Moreover, this resulted in a redistribution of sperm with the rapid class declining in number with time, but still showing an overall velocity increase. The flexibility of the approach permits parameter modifications with the experimental needs, allowing us to conduct a comprehensive examination of sperm motility. This adaptability facilitated data acquisition which can be computed at different frame rates, extended time periods, and within deeper observation chambers. The suggested approach for sperm analysis exhibits potential as a valuable augmentation to current diagnostic instruments.

Advancements in Genetic Biomarkers and Exogenous Antioxidant Supplementation for Safeguarding Mammalian Cells against Heat-Induced Oxidative Stress and Apoptosis

Heat stress represents a pervasive global concern with far-reaching implications for the reproductive efficiency of both animal and human populations. An extensive body of published research on heat stress effects utilizes controlled experimental environments to expose cells and tissues to heat stress and its disruptive influence on the physiological aspects of reproductive phenotypic traits, encompassing parameters such as sperm quality, sperm motility, viability, and overall competence. Beyond these immediate effects, heat stress has been linked to embryo losses, compromised oocyte development, and even infertility across diverse species. One of the primary mechanisms underlying these adverse reproductive outcomes is the elevation of reactive oxygen species (ROS) levels precipitating oxidative stress and apoptosis within mammalian reproductive cells. Oxidative stress and apoptosis are recognized as pivotal biological factors through which heat stress exerts its disruptive impact on both male and female reproductive cells. In a concerted effort to mitigate the detrimental consequences of heat stress, supplementation with antioxidants, both in natural and synthetic forms, has been explored as a potential intervention strategy. Furthermore, reproductive cells possess inherent self-protective mechanisms that come into play during episodes of heat stress, aiding in their survival. This comprehensive review delves into the multifaceted effects of heat stress on reproductive phenotypic traits and elucidates the intricate molecular mechanisms underpinning oxidative stress and apoptosis in reproductive cells, which compromise their normal function. Additionally, we provide a succinct overview of potential antioxidant interventions and highlight the genetic biomarkers within reproductive cells that possess self-protective capabilities, collectively offering promising avenues for ameliorating the negative impact of heat stress by restraining apoptosis and oxidative stress.