An electron microscope study of the axonemal ultrastructure in human spermatozoa from male smokers and nonsmokers

[Male infertility, environment and lifestyle]

BACKGROUND

Since the 1970s, there has been a quantitative and qualitative decline in sperm parameters. The main hypothesis to explain such a rapid evolution is the involvement of environmental and behavioral phenomena.

METHODS

A bibliographic search limited to English and French literature in men published before 7/2023 was carried out on the links between fertility and pollution, xenobiotics, tobacco, narcotics, cannabis, alcohol, weight, sport, sedentary lifestyle, sleep and anabolics.

RESULTS

Profound changes in lifestyle have occurred over the past 50 years: reduced sleep time, sedentary lifestyle, dietary changes, tobacco consumption, use of narcotics and anabolics. These changes have a proven impact on spermogram parameters, and should be corrected in an effort to optimize reproductive health. Other environmental parameters: pollution, exposure to heavy metals, exposure to xenobiotics, phthalates and pesticides… will be more difficult to exclude from patients' daily lives, but deserve to be taken more into account.

CONCLUSION

This review should help the urologist to assess and counsel patients in order to improve their reproductive health. These factors should be routinely investigated in infertile men.

Impact of Tobacco and Marijuana on Infertility and Early Reproductive Wastage

Reducing exposure to tobacco and marijuana during preconception and early pregnancy is a critical area of intervention for obstetricians, gynecologists, and other reproductive health care professionals. Beyond the deleterious personal health effects, both substances have been extensively associated with short-term and long-term detrimental effects to gametogenesis, fecundity, as well as tissue level effects in the reproductive tracts. When tobacco and marijuana do not impair the ability to achieve pregnancy, an increasing body of literature suggests either may be associated with increased risk of early pregnancy loss and reproductive wastage. In this review, we will discuss what is known about how tobacco and marijuana affect the male and female reproductive systems and highlight how these consequences may impair attempts at successful conception and pregnancy continuation beyond the first trimester.

Comparative effects of combined use of alcohol with cannabis and tobacco on testicular function in rats

Alcoholism has been linked to problems with male reproductive function. The combined effects of alcohol, cannabis, and tobacco were compared in this study. A total of 35 rats were assigned randomly into seven groups A-G: animals in A were administered distilled water. Animals in B-G were either administered alcohol orally (30 ml 40% alcohol) or exposed to smoke from ignited tobacco (exposure to smoke from 0.7 g tobacco for 5 min) or cannabis (exposure to smoke from 0.7 g tobacco and cannabis for 5 min): B (orally administered alcohol), C (exposed to the smoke from tobacco), D (exposed to smoke from cannabis), E (treated with alcohol and exposed to smoke from tobacco), F (treated with alcohol and exposed to smoke from cannabis), G (treated with alcohol and exposed to smokes from tobacco and cannabis). Assays were carried on the testicular homogenate after a 14-day treatment. There was a significant increase in activity of alkaline phosphatase (P ≤ 0.05), concentrations of cholesterol, glutathione reductase, and malondialdehyde in treated rats by the co-administration of alcohol with cannabis and tobacco compared with the control group. The combined treatment also caused degeneration and morphological distortions of testicular cells. The biochemical and histoarchitectural change was due to oxidative damage attributable to the synergistic effects. The high binding energy of tetrahydrocannabinol ligand to prostate acid phosphatase may be a prediction that the ligand can have an inhibitory effect on the function of enzymes in the prostate.

People smoke for nicotine, but lose sexual and reproductive health for tar: a narrative review on the effect of cigarette smoking on male sexuality and reproduction

PURPOSE

To systematically review the impact of smoking habits on cardiovascular (CV) as well as on male sexual and reproductive function and to provide updated evidence on the role of electronic cigarettes (e-Cig) on the same topics.

METHODS

A comprehensive Medline, Embase, and Cochrane search was performed including the following words: smoking, CV system, CV risk, erectile dysfunction (ED), and male fertility. Publications from January 1, 1969 up to February 29, 2020 were included.

RESULTS

Smoking has a tremendous negative impact on CV mortality and morbidity. Current smoking behavior is also negatively associated with erectile dysfunction (ED) and impaired sperm parameters. E-Cig can release significantly lower concentrations of harmful substances when compared to regular combustible cigarettes. Whether or not the latter can result in positive CV, sexual, and fertility outcomes is still under study. Preliminary studies showed that exposure to e-Cig leads to lower vascular damage when compared to the traditional cigarette use. However, data on the long-term effects of e-Cig are lacking. Similarly, preliminary data, obtained in animal models, have suggested a milder effect of e-Cig on erectile function and sperm parameters.

CONCLUSION

Available evidence showed that e-Cig are much less dangerous when compared to the traditional tobacco use. However, it should be recognized that the risk related to e-Cig is still higher when compared to that observed in non-smoking patients. Hence, e-Cig should be considered as a potential tool, in the logic of harm reduction, to reduce the CV, sexual and fertility risk in patients refractory to the fundamental, healthy choice to definitively quit smoking.

Smoke, alcohol and drug addiction and male fertility

In recent decades, the decline in human fertility has become increasingly more worrying: while therapeutic interventions might help, they are vexing for the couple and often burdened with high failure rates and costs. Prevention is the most successful approach to fertility disorders in males and females alike. We performed a literature review on three of the most common unhealthy habits - tobacco, alcohol and drug addiction - and their reported effects on male fertility. Tobacco smoking is remarkably common in most first-world countries; despite a progressive decline in the US, recent reports suggest a prevalence of more than 30% in subjects of reproductive age - a disturbing perspective, given the well-known ill-effects on reproductive and sexual function as well as general health. Alcohol consumption is often considered socially acceptable, but its negative effects on gonadal function have been consistently reported in the last 30 years. Several studies have reported a variety of negative effects on male fertility following drug abuse - a worrying phenomenon, as illicit drug consumption is on the rise, most notably in younger subjects. While evidence in these regards is still far from solid, mostly as a result of several confounding factors, it is safe to assume that cessation of tobacco smoking, alcohol consumption and recreational drug addiction might represent the best course of action for any couple trying to achieve pregnancy.

From sperm to offspring: Assessing the heritable genetic consequences of paternal smoking and potential public health impacts

Individuals who smoke generally do so with the knowledge of potential consequences to their own health. What is rarely considered are the effects of smoking on their future children. The objective of this work was to review the scientific literature on the effects of paternal smoking on sperm and assess the consequences to offspring. A literature search identified over 200 studies with relevant data in humans and animal models. The available data were reviewed to assess the weight of evidence that tobacco smoke is a human germ cell mutagen and estimate effect sizes. These results were used to model the potential increase in genetic disease burden in offspring caused by paternal smoking, with specific focus on aneuploid syndromes and intellectual disability, and the socioeconomic impacts of such an effect. The review revealed strong evidence that tobacco smoking is associated with impaired male fertility, and increases in DNA damage, aneuploidies, and mutations in sperm. Studies support that these effects are heritable and adversely impact the offspring. Our model estimates that, with even a modest 25% increase in sperm mutation frequency caused by smoke-exposure, for each generation across the global population there will be millions of smoking-induced de novo mutations transmitted from fathers to offspring. Furthermore, paternal smoking is estimated to contribute to 1.3 million extra cases of aneuploid pregnancies per generation. Thus, the available evidence makes a compelling case that tobacco smoke is a human germ cell mutagen with serious public health and socio-economic implications. Increased public education should be encouraged to promote abstinence from smoking, well in advance of reproduction, to minimize the transmission of harmful mutations to the next-generation.

Paternal smoking and germ cell death: A mechanistic link to the effects of cigarette smoke on spermatogenesis and possible long-term sequelae in offspring

Paternal exposure to constituents of cigarette smoke (CS) is reportedly associated with infertility, birth defects and childhood cancers even though the mechanism behind this relationship is still unclear. Chronic cigarette smoking by men leads to poor sperm quality and quantity mainly through oxidative stress and also direct assault by CS metabolites. Among several carcinogenic and teratogenic components of cigarette smoke condensate (CSC), polycyclic aromatic hydrocarbons (PAHs) display a preeminent role in accelerating germ cell death via the cytoplasmic transcription factor, aryl hydrocarbon receptor (AHR) that is present across all stages of spermatogenesis. Activation of AHR by growth factors though benefits normal cellular functions, its mediation by CSC in a spermatocyte cell line [Gc2(spd)ts] adversely affects the expression of a battery of genes associated with antioxidant mechanisms, cell proliferation and apoptosis, and cell cycle progress. Besides, the CSC-mediated cross talk either between AHR and NRF2 or AHR-NRF2 and MAPKs pathways inhibits normal proliferation of the spermatogenic GC-2spd(ts) cells in vitro and cell death of spermatocytes in vivo. Pharmacological inactivation of CSC-induced AHR but not its genetic manipulation seems preventing DNA and cell membrane damage in Gc2(spd)ts. Data from recent reports suggest that the cigarette smoke affects both the genomic and epigenomic components of the sperm and attributes any associated changes to developmental defects in the offspring. Thus, the studies discussed here in this review shed light on possible mechanistic factors that could probably be responsible for the paternally mediated birth defects in the offspring following exposure to the toxic constituents of cigarette smoke.

Smoking and Male Infertility: An Evidence-Based Review

Many studies have reported that the contents of cigarette smoke negatively affect sperm parameters, seminal plasma, and various other fertility factors. Nevertheless, the actual effect of smoking on male fertility is not clear. The effect of smoking on semen parameters is based on the well-established biological finding that smoking increases the presence of reactive oxygen species, thereby resulting in oxidative stress (OS). OS has devastating effects on sperm parameters, such as viability and morphology, and impairs sperm function, hence reducing male fertility. However, not all studies have come to the same conclusions. This review sheds light upon the arguable association between smoking and male fertility and also assesses the impact of non-smoking routes of tobacco consumption on male infertility. It also highlights the evidence that links smoking with male infertility, including newly emerging genetic and epigenetic data, and discusses the clinical implications thereof.

The hazardous effects of tobacco smoking on male fertility

The substantial harmful effects of tobacco smoking on fertility and reproduction have become apparent but are not generally appreciated. Tobacco smoke contains more than 4000 kinds of constituents, including nicotine, tar, carbonic monoxide, polycyclic aromatic hydrocarbons, and heavy metals. Because of the complexity of tobacco smoke components, the toxicological mechanism is notably complicated. Most studies have reported reduced semen quality, reproductive hormone system dysfunction and impaired spermatogenesis, sperm maturation, and spermatozoa function in smokers compared with nonsmokers. Underlying these effects, elevated oxidative stress, DNA damage, and cell apoptosis may play important roles collaboratively in the overall effect of tobacco smoking on male fertility. In this review, we strive to focus on both the phenotype of and the molecular mechanism underlying these harmful effects, although current studies regarding the mechanism remain insufficient.

Modeling the effect of cigarette smoke on hexose utilization in spermatocytes

We set out to determine whether the addition of an aryl hydrocarbon receptor (AHR) antagonist has an effect on glucose/fructose utilization in the spermatocyte when exposed to cigarette smoke condensate (CSC). We exposed male germ cells to 5 and 40 μg/mL of CSC ± 10 μmol/L of AHR antagonist at various time points. Immunoblot expression of specific glucose/fructose transporters was compared to control. Radiolabeled uptake of 2-deoxyglucose (2-DG) and fructose was also performed. Spermatocytes utilized fructose nearly 50-fold more than 2-DG. Uptake of 2-DG decreased after CSC + AHR antagonist exposure. Glucose transporters (GLUTs) 9a and 12 declined after CSC + AHR antagonist exposure. Synergy between CSC and the AHR antagonist in spermatocytes may disrupt the metabolic profile in vitro. Toxic exposures alter energy homeostasis in early stages of male germ cell development, which could contribute to later effects explaining decreases in sperm motility in smokers.

Increase of 210Po levels in human semen fluid after mussel ingestion

Polonium-210 ((210)Po) radioactive concentrations were determined in human semen fluid of vasectomized non-smoker volunteers. The (210)Po levels ranged from 0.10 to 0.39 mBq g(-1) (mean: 0.23 ± 0.08 mBq g(-1)). This value decreased to 0.10 ± 0.02 mBq g(-1) (range from 0.07 to 0.13 mBq g(-1)) after two weeks of a controlled diet, excluding fish and seafood. Then, volunteers ate during a single meal 200 g of the cooked mussel Perna perna L., and (210)Po levels were determined again, during ten days, in semen fluid samples collected every morning. Volunteers continued with the controlled diet and maintained sexual abstinence through the period of the experiment. A 300% increase of (210)Po level was observed the day following mussel consumption, with a later reduction, such that the level returned to near baseline by day 4.

Oxidative stress and epididymal sperm transport, motility and morphological defects

OBJECTIVES

Radical oxidative species (ROS) have an important effect on sperm quality and quantity. Oxidative stress (OS) occurs when production of potentially destructive reactive oxygen species (ROS) exceeds the body's own natural antioxidant defenses, resulting in cellular damage. OS is a common pathology seen in approximately half of all infertile men. Increased ROS generation and reduced antioxidant capacity is negatively correlated with sperm concentration and motility in infertile men. For the first time, we used a more stable and reliable sensitive carbonyl protein (CP) detection method to determine ROS in seminal plasma than measuring ROS directly to clarify the effect of OS on spermatozoa in terms of protein dysfunction. This is the first report to measure CP in seminal plasma as an indicator of OS. Furthermore, for the first time we correlated the results of CP measurement with light microscopy in combination with ultrastructural analysis by electron microscopy.

MATERIAL AND METHODS

20 patients with idiopathic oligoasthenoteratozoospermia (iOAT) and 10 fertile controls were enrolled in this study. CP values were measured by enzyme-linked immuno sorbent assay (ELISA) to detect the level of OS. Transmission electron microscope (TEM) was used to detect axonemal anomalies.

RESULTS

Compared to fertile controls, statistically highly significant higher degrees of abnormal sperm parameters (P<0.001) could be found in iOAT patients. CP values were highly significantly elevated in iOAT patients than in normal controls (P<0.001). A statistically highly significant difference in different axonemal anomalies were found between iOAT patients and normal controls (P<0.001). CP values have been found to be positively correlated with different axonemal anomalies (absence of axoneme (r(2)=0.841), missing of central singlet tubules (r(2)=0.702) and missing of outer doublet tubules (r(2)=0.869). A statistically negative correlation were found between different axonemal anomalies (absent axoneme (r(2)=-0.780), missing of central singlet tubules (r(2)=-0.611), and missing of outer doublet tubules (r(2)=-0.738) and forward progressive sperm motility.

CONCLUSION

High levels of CP can be measured in iOAT patients, indicating that OS could underlie the aetipopathogenesis of the syndrome. OS negatively affects flagellar axonemal structure with subsequent impairment of forward progressive sperm motility. This can put an attention for antioxidants as a therapy for iOAT syndrome and further research to find how to decrease ROS production.

Seminal plasma cotinine and insulin-like growth factor-I in idiopathic oligoasthenoteratozoospermic smokers

OBJECTIVE

To assess seminal plasma insulin-like growth factor-I (IGF-I) levels in cigarette smokers with idiopathic oligoasthenoteratozoospermia (iOAT).

PATIENTS AND METHODS

In all, 110 men were divided into fertile healthy non-smokers, fertile smokers, infertile non-smokers with iOAT and infertile smokers with iOAT. Semen was analysed, and seminal cotinine and seminal IGF-I levels estimated.

RESULTS

There were significantly lower seminal IGF-I levels in the smokers and in men with iOAT than in controls, and in both iOAT groups. Smokers, either fertile or with iOAT had significantly lower levels than in controls in mean semen volume, sperm production index, percentage of motile sperms, rapid linear forward progressive motility, linear velocity and sperm normal forms. Smokers with iOAT had significantly lower levels than non-smokers with iOAT in mean sperm production index, rapid linear forward progressive motility and linear velocity. In smokers, seminal cotinine was significantly and negatively correlated with both seminal IGF-I and sperm motility, while seminal IGF-I was positively correlated with the percentage of motile spermatozoa.

CONCLUSION

Smoking effects on sperm variables could be mediated by decreased seminal IGF-I.

Clinical relevance of oxidative stress in male factor infertility: an update

Male factor has been considered a major contributory factor to infertility. Along with the conventional causes for male infertility such as varicocele, cryptorchidism, infections, obstructive lesions, cystic fibrosis, trauma, and tumors, a new, yet important cause has been identified: oxidative stress. Oxidative stress (OS) is a result of the imbalance between reactive oxygen species (ROS) and antioxidants in the body, which can lead to sperm damage, deformity and eventually male infertility. This involves peroxidative damage to sperm membrane and DNA fragmentation at both nuclear and mitochondrial levels. OS has been implicated as the major etiological factor leading to sperm DNA damage. OS-induced DNA damage can lead to abnormalities in the offspring including childhood cancer and achondroplasia. In this article, we discuss the need of ROS in normal sperm physiology, the mechanism of production of ROS and its pathophysiology in relation to male reproductive system. The benefits of incorporating antioxidants in clinical and experimental settings have been enumerated. We also highlight the emerging concept of utilizing OS as a method of contraception and the potential problems associated with it.

The influence of cigarette smoking on human sperm quality and DNA fragmentation

The aim of the present study was to evaluate consequences of cigarette smoking on male gametes. In this prospective study, sperm parameters such as sperm density, motility, viability and normal morphology were measured according to the WHO criteria. In addition to these standard parameters, we analysed the degree of DNA fragmentation in spermatozoa using the TUNEL-assay with flow cytometry detection in 57 non-smokers and 51 smokers seeking for infertility counselling. The smoking intoxication was assessed by questionnaire and measured with the CO-Tester. We show that smokers' spermatozoa have a significantly higher DNA fragmentation than non-smokers (32% versus 25.9%, p<0.01). In contrast there is no significant difference in conventional parameters between smokers and non-smokers. The degree of sperm DNA fragmentation is not significantly correlated with any of the conventional parameters. These findings suggest that cigarette smoking may have deleterious effects on sperm nuclear quality and that sperm DNA fragmentation can therefore be considered as an independent parameter with diagnostic, prognostic, and strategic value in the treatment of infertility.

Influence of cigarette smoking on spermatozoa via seminal plasma

Numerous investigations have been conducted on the relationship between cigarette smoking and male infertility, however, the exact molecular mechanisms are not well understood in most of the cases. Few studies have indicated the direct effect of seminal plasma (SP) [in different dilutions with phosphate buffer solution (PBS)] from smokers (SM) on the sperm functional parameters from nonsmokers (non-SM). The aim of this study was to provide evidence that cigarette smoking affects male fertility via altering the sperm quality. Our results indicated that exposure of spermatozoa from the non-SM to the SP from the SM yielded a significant reduction in the sperm motility and acrosome reaction and an elevation in the amount of malondialdehyde (MDA), in a certain time course. Exposure of spermatozoa from the SM to the SP from the non-SM or with PBS resulted in the nonsignificant improvement in the altered sperm functional parameters indicating removal of SM's SP and then subsequent reconstitution with physiological media could be of clinical significance in the various assisted reproductive technologies applied for SM. However, the detrimental effect of SM's SP on non-SM's spermatozoa was prominent. In addition, as spermatozoa in SM's SP are susceptible to peroxidative damages, men with such cells who wish to have children should especially benefit from quitting smoking.

The male reproductive system and its susceptibility to endocrine disrupting chemicals

In the past years, there has been increased interest in assessing the relationship between impaired male fertility and environmental factors. Human male fertility is a complex process and therefore a great variety of sites may be affected by exogenous noxae. Lifestyle factors as well as various environmental and occupational agents may impair male fertility. Many studies have been published reporting on reproductive dysfunctions in male animals and humans. Especially environmental pollutants with endocrine activity are discussed as a possible cause of this detrimental development. Evidence from animal experiments show that substances with oestrogenic and antiandrogenic properties may cause hypospadia, cryptorchidism, reduction of sperm density and an increase of testicular tumours. Many adverse effects on animal male fertility have been documented for phthalates and some chlorinated hydrocarbons such as polychlorinated biphenyls and polychlorinated dibenzo-p-dioxins. For other chemicals such as bisphenol A and nonylphenols animal data are conflicting. Environmental pollutants may mediate their effects by receptor binding, modulation of hormone-regulated mechanisms or direct toxic effects. Data on environmental chemicals and human male fertility are scarce, and risk assessment is mostly based on the results of animal studies. However, there are indications that exposure to endocrine active chemicals during early development may alter hormone responsiveness in adulthood. Furthermore, some of the chemicals are found in fluids that are associated with human reproduction, such as follicular fluid, seminal fluid and cervical mucus. Recent studies suggest a correlation between pesticide exposure and standard semen parameters as well as in vitro fertilization rates.

Effects of paternal cigarette smoking on testicular function, sperm fertilizing capacity, embryonic development, and blastocyst capacity for implantation in rats

We evaluated the effects of paternal smoking on testicular function, sperm fertilizing capacity, embryonic development, and blastocyst capacity for implantation. Rats of group A were exposed to cigarette smoke for 10 weeks. Rats of group B were exposed to the smoke of incense sticks for 10 weeks. Rats of group C served as a control group. Rats of group D were exposed to cigarette smoke for 7 weeks only. Experimental period was 10 weeks in all groups. At the end of the experimental period serum testosterone responses to human chorionic gonadotropin stimulation, androgen-binding protein activity in testicular cytosols, epididymal sperm motility, and oocyte fertilization rate, oocyte cleavage rate, and blastocyst development rate after in vitro fertilization (IVF) trials were significantly smaller in group A compared with groups B and C. In contrast, fertilization rate, cleavage rate, and blastocyst development rate after intracytoplasmic sperm injection (ICSI) procedures were not significantly different among groups A, B, C, and D. Both after IVF trials and ICSI techniques, the proportion of the alive offspring to the number of transferred oocytes was significantly smaller in group A than in groups B and C. Cigarette smoke-exposure results in a secretory deficiency of Leydig and Sertoli cells leading to an impaired epididymal sperm maturation process and diminished capacity of spermatozoa to penetrate oocytes. In addition paternal cigarette smoke exposure affects the embryonic ability for implantation.

Semen quality of male smokers and nonsmokers in infertile couples

OBJECTIVE

To investigate the effect of cigarette smoking on main sperm variables.

DESIGN

Cohort study.

SETTING

Men attending the andrology laboratory in the context of infertility investigation in the couple.

PATIENT(S)

Eight hundred thirty-nine smokers and 1,266 non-smokers were enrolled; 655 smokers and 1,131 nonsmokers fulfilled the inclusion criteria and were compared. Standard clinical analysis of semen.

RESULT(S)

Cigarette smoking was associated with a significant decrease in sperm density (-15.3%), total sperm count (-17.5%), total number of motile sperm (-16.6%), and citrate concentration (-22.4%). The percentage of normal forms was significantly reduced in smokers, and sperm vitality, ejaculate volume, and fructose concentration were slightly but nonsignificantly affected.

CONCLUSION(S)

Cigarette smoking is associated with reduced semen quality.

Delayed conception and active and passive smoking. The Avon Longitudinal Study of Pregnancy and Childhood Study Team

OBJECTIVE

To determine whether passive as well as active smoking by women or smoking by men is associated with delayed conception, after adjustment for confounding factors.

DESIGN

Population study of couples expecting a baby. Logistic regression was performed to identify factors associated with delayed conception.

SETTING

The Avon Health Authority area, United Kingdom.

PATIENT(S)

All couples expected to deliver between April 1991 and December 1992.

INTERVENTION(S)

Questionnaires administered early in pregnancy.

MAIN OUTCOME MEASURE(S)

Time taken to conceive, categorized as <6 months, 6-11 months, 1-3 years, and >3 years.

RESULT(S)

After correction for confounding factors, delayed conception was statistically significantly associated with both active smoking by the woman (odds ratio [OR] 1.23 [95% CI 0.98-1.49] for > 6 months and 1.54 [95% CI 1.19-2.01] for >12 months) and her exposure to passive smoking (OR 1.17 [95% CI 1.02-1.37] and 1.14 [95% CI 0.92-1.42]) compared with women with no exposure to tobacco smoke (referent). Heavy smoking by men was independently associated with delayed conception. In active smokers, the effect increased with the number of cigarettes.

CONCLUSION(S)

Smoking by men and passive and active smoking by women are associated with delayed conception.