Nicotine, cotinine, and trans-3-hydroxycotinine levels in seminal plasma of smokers: effects on sperm parameters

Environmental and occupational factors affecting fertility and IVF success

Reproductive function has been shown to be sensitive to changes in the physical, psychosocial and chemical environments. Although reproductive effects of occupational exposure to hazardous chemicals have been well documented in the literature, the potential effects of chemical contaminants at levels representative of contemporary exposures in the general population are much less certain. Evidence for adverse effects of exposure to environmental contaminants is more conclusive among the lower animals than for humans where considerable controversy remains. In addition to potential reproductive hazards of exposure to environmental contaminants, there is also evidence for adverse reproductive effects of the physical and psychosocial environments. In this review we focus on the difficulties involved in linking exposure to putative hazardous substances in environmental and occupational settings to adverse reproductive outcomes, especially success of IVF procedures. We highlight the plausibility of adverse events through animal and cell studies and the application of these results to the interpretation of human data. We consider both the male and female partners since it is essentially their combined contributions of gametes which may be affected by chemicals, which lead to successful outcomes.

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.

Tobacco smoke exposure and serum cotinine in a random sample of adults living in Verona, Italy

In this study, the authors attempted to validate answers to smoking-habit questions contained in the European Community Respiratory Health Survey questionnaire. The respondents were invited to visit the chest clinic at Verona, Italy, and their serum cotinine levels were measured. The authors invited each of 504 subjects to complete a respiratory interview and to give a blood sample for a radioimmunoassay serum cotinine measurement. A total of 375 subjects responded, of whom 129 were smokers (34.4%), 79 were exsmokers (21.1%), and 167 (44.5%) had never smoked. Exposure to environmental tobacco smoke was reported by 216 subjects (57.6% [mean exposure = 3.8 hr/day (+/- 3.4 hr/day standard deviation)]). In smokers, serum cotinine levels were directly related to the number of cigarettes smoked/day. The authors excluded from analysis nonsmokers who had serum cotinine levels that were > or = 14 ng/ml, and the resulting mean values were 1.7 ng/ml (+/- 2.1 ng/ml standard deviation) in nonsmokers unexposed to environmental tobacco smoke and 2.6 ng/ml (+/- 2.6 ng/ml standard deviation) (p < .002) in nonsmokers exposed to environmental tobacco smoke. There was a relationship between serum cotinine levels and hours of exposure to environmental tobacco smoke (R2 = .136, p < .05). Serum cotinine, which is an objective and accepted measure of tobacco exposure, confirmed the validity of the European Community Respiratory Health Survey questionnaire with respect to smoking habits and environmental tobacco smoke exposure.

Nicotine toxicity to the ultrastructure of the testis in rats

OBJECTIVE

To investigate the influence of nicotine exposure on the ultrastructure of the rat testis.

MATERIALS AND METHODS

Twenty rats were injected with nicotine at a dose of 0.4 mg/100 g body weight daily for 3 months; a group of 20 control rats matched for weight and age were injected with saline only for the same duration. The testes were then harvested and examined by transmission electron microscopy.

RESULTS

Rats given nicotine showed: thickening of the tunica propria, caused by an increase in the collagen fibres under the irregular basal lamina; degeneration of junctional specializations between the Sertoli cells, with malformed nuclei showing condensed chromatin; Sertoli cells with numerous polymorphic mitochondria with irregular cristae and an electron-dense matrix. The germ cells were degenerated, spermatids retained excess cytoplasm and accumulated electron-dense lipid droplets in the cytoplasm. The acrosomes were irregular and abnormally configured.

CONCLUSION

There were ultrastructural alterations in rats exposed to nicotine that could be attributed to the detrimental effects of nicotine on germ cells, peritubular structures and Sertoli cells.

Resveratrol, a natural aryl hydrocarbon receptor antagonist, protects sperm from DNA damage and apoptosis caused by benzo(a)pyrene

Benzo(a)pyrene (BaP), an aryl hydrocarbon receptor (AhR) ligand present in cigarette smoke and car exhaust, is thought to have negative effects on male reproduction. We hypothesized that BaP damages sperm through AhR activation, phase I enzyme induction, DNA adduct formation, and increased germ cell apoptosis in the testis, and that resveratrol, a natural competitive inhibitor of the AhR found in some red wines, could prevent the adverse effects of BaP on sperm. Male Balb C mice were injected subcutaneously (s.c.) for 5 weeks with a range of BaP doses (0.5 mg/kg to 50 mg/kg). Live sperm were obtained from the vas deferens, counted, and stained to measure annexin-V positive (apoptotic) cells. In a subsequent study, mice were injected for 5 weeks with corn oil (control), BaP (5 mg/kg/week), or BaP plus resveratrol (50 mg/kg/week) (n = 3 per group). Immunohistochemistry (IHC) was performed on testis sections for the determination of CYP1A1, BaP diol epoxide (BPDE) DNA adducts, and apoptosis and the results quantified by using the HSCORE, a semiquantitative scoring system. Our results demonstrated that sperm counts after 5 weeks were inversely correlated to BaP dosage. BaP (0.5 to 5 mg/week) positively correlated with sperm apoptosis while higher doses increased sperm necrosis. CYP1A1 protein was observed mainly in interstitial cells of some testis sections, but there was no significant induction by BaP. BPDE DNA adducts were induced in all components of the seminiferous tubules by BaP and suppressed by resveratrol: median HSCORE (interquartile range) control 61 (52-71.5); BaP 213 (192-248), P = 0.01 compared to control; BaP plus resveratrol 83 (70-90). BaP significantly increased apoptosis, mainly in spermatogonia: medain HSCORE (interquartile range) BaP 189 (161-223) versus control 83 (57-93), P < 0.01; and this effect was abrogated by resveratrol. Median HSCORE for BaP plus resveratrol was 112 (range 99-121). In summary, BaP caused increased sperm cell BPDE DNA adduct formation and apoptosis in the mouse. The natural AhR antagonist, resveratrol diminished BaP-induced DNA adducts and apoptosis in seminiferous tubules.

Cigarette smoking and the risk of male factor subfertility: minor association between cotinine in seminal plasma and semen morphology

OBJECTIVE

To evaluate the impact of cigarette smoking on male factor subfertility and the semen parameters of sperm count, motility, and morphology by questionnaire and determination of the cotinine concentrations in blood and seminal plasma of fertile and subfertile males.

DESIGN

Case-control study of 107 fertile and 103 subfertile males who provided a standardized blood and semen specimen and completed a self-administered questionnaire about their smoking habits.

SETTING

Outpatient fertility clinic of the University Medical Centre St. Radboud, Nijmegen, The Netherlands.

PATIENT(S)

One hundred seven fertile and 103 subfertile males.

INTERVENTION(S)

Vena puncture and semen collection.

MAIN OUTCOME MEASURE(S)

Blood and seminal plasma cotinine levels in relation to semen parameters.

RESULT(S)

A higher frequency of cigarette smoking was observed in subfertile males than in fertile males, with an odds ratio of 1.7 (95% confidence interval, 0.9-3.2). The self-reported number of cigarettes smoked per day correlated with the cotinine concentrations in blood and seminal plasma for both groups. A small but statistically significant correlation was found between cotinine concentrations in seminal plasma and the percentage of abnormal sperm morphology, but not for other semen parameters (r(s) = 0.19).

CONCLUSION(S)

Although the mechanism of the toxicity of cotinine on sperm morphology is not clear, this study indicates only a minor effect of cigarette smoking on male factor subfertility, which is probably due to compounds in cigarette smoke other than nicotine (cotinine).

Induction of vaginal Lactobacillus phages by the cigarette smoke chemical benzo[a]pyrene diol epoxide

Because smoking increases a woman's risk of contracting bacterial vaginosis (BV), which is manifested by a reduction of vaginal lactobacilli and an overgrowth of anaerobic bacteria, chemicals contained in cigarette smoke were analyzed in vitro to determine their role in reducing lactobacilli. The result showed that trace amounts of benzo[a]pyrene diol epoxide (BPDE), which can be found in vaginal secretion of women who smoke, significantly increased phage induction in lactobacilli. This finding implies that smoking may reduce vaginal lactobacilli by promoting phage induction.

Male factor subfertility: possible causes and the impact of nutritional factors

OBJECTIVE

To review possible causes for male factor subfertility with emphasis on nutritional factors such as zinc and folate.

DESIGN

A literature search was performed on MEDLINE and via bibliographies of published works.

RESULT(S)

Many causes for male factor subfertility are described in the literature. Both environmental and genetic factors could play a role. However, the pathogenesis of male factor infertility is poorly understood, including the role of specific micronutrients such as zinc and folate. Both zinc and folate are involved in the synthesis of DNA and RNA. Despite the fact that zinc deficiency leads to several clinical symptoms such as decreased spermatogenesis and impaired male fertility, the exact pathophysiology has not been clarified.

CONCLUSION(S)

Because most causes of male factor subfertility are unknown, more research is needed. Because male factor subfertility due to nutritional deficiencies is in principle amenable to curative and/or preventive action by supplementation, emphasis should be put on studies on the effect of specific nutrients on male fertility.

Fertilizing ability of DNA-damaged spermatozoa

In order to investigate the fertilizing ability of DNA-damaged sperm, they were exposed to gamma radiation prior to insemination. The presence of DNA-strand breaks were detected by the TUNEL test. Fertilization rates of 64.3, 59.9, 58.5, and 61.1% were achieved when sperm were subjected to 5, 10, 50, and 100 GY, respectively. This rate was 53.2% in the control group with no significant difference (P > 0.01). The blastocyst development was decreased from 49.8% in the control group to 20.3, 7.8, 3.4, and 2.3% with sperm exposed to doses of 5, 10, 50, and 100 GY, respectively. Of the transferred blastocyst in the control group, 69.8% were implanted and 33.9% developed into live fetuses. These rates were 57.1 and 21. 4%, 20 and 0% when sperm were exposed to doses of 5 and 10 GY with a significant difference (P < 0.01). The present study clearly shows that DNA-damaged sperm (regardless of degree of damage) have the ability to fertilize the oocyte, but that embryonic development is very much related to the degree of DNA damage. However, the oocyte has the capacity to repair DNA damage of sperm when it is damaged less than 8%. Damage beyond this level will result in low rate of embryonic development and high early pregnancy loss. J. Exp. Zool. 284:696-704, 1999.

Detection of benzo(a)pyrene diol epoxide-DNA adducts in sperm of men exposed to cigarette smoke

OBJECTIVE

To determine whether the adducts formed when benzo(a)pyrene, a diol epoxide derivative, binds covalently to DNA (BPDE-DNA adducts) are detectable in the sperm of men who smoke cigarettes.

DESIGN

Prospective study.

SETTING

The Toronto Hospital IVF-ET program.

PATIENT(S)

Twenty-three patients with normal seminal parameters: 11 smokers (20.6 +/- 0.7 cigarettes per day) and 12 nonsmokers.

INTERVENTION(S)

Semen samples obtained by masturbation.

MAIN OUTCOME MEASURE(S)

Seminal plasma samples were assessed for cotinine by RIA. Sperm were treated with dithiothreitol to release disulfide bonds and allow for DNA binding, then exposed to an anti-BPDE monoclonal antibody, a biotinylated antibody, and streptavidin-conjugated peroxidase. Staining intensity scores, determined in 100 cells per individual, were correlated with seminal plasma cotinine levels, a marker of smoking.

RESULT(S)

Cotinine levels correlated highly with the number of cigarettes smoked per day. Mean cotinine levels and mean staining intensity scores were higher in smokers than in nonsmokers. Staining intensity correlated highly with cotinine levels.

CONCLUSION(S)

We demonstrated, for the first time, that BPDE-DNA adducts in sperm cells are increased by smoking; we also detected comparatively high levels in nonsmokers, which indicates that environmental exposure also is substantial. The formation of adducts in spermatozoa is a potential source of transmissible prezygotic DNA damage.

Sperm chromatin damage associated with male smoking

Cigarette smoke is a rich source of mutagens and carcinogens; thus, we have investigated the effects of male smoking on the DNA of human sperm. This was performed using the sperm chromatin structure assay (SCSA), which measures the sensitivity of sperm DNA to acid induced denaturation, and the terminal deoxynucleotidyl transferase assay (TdTA), which measures DNA strand breaks by addition of the biotinylated nucleotide dUTP to 3'-OH ends of DNA, sites of DNA breakage, using the enzyme terminal deoxynucleotidyl transferase. Sperm from subjects who smoked were significantly more sensitive to acid induced denaturation than non-smokers (P<0.02) and possessed higher levels of DNA strand breaks (P<0.05). We hypothesise that smoking damages the chromatin structure and produces endogenous DNA strand breaks in human sperm. These changes may result in sperm DNA mutations, that predispose offspring to greater risk of malformations, cancer and genetic diseases.

Detection of oxidative DNA damage in human sperm and the association with cigarette smoking

The present study aims to evaluate oxidative DNA damage in human sperm and the association with cigarette smoking. The level of 8-hydroxydeoxyguanosine (8-OHdG) in sperm DNA, cotinine concentration in seminal plasma, and conventional seminal parameters such as semen volume, sperm density, viability, motility, and normal morphology were determined in 60 healthy subjects. It was found that the sperm DNA of smokers contained a significantly higher amount of 8-OHdG than that of nonsmokers (6.19 +/- 1.71 vs. 3.93 +/- 1.33 8-OHdG/10(5) dG, P < 0.001). The level of 8-OHdG in sperm DNA was also closely correlated to seminal cotinine concentration (r = 0.38, P < 0.05). These findings suggest that cigarette smoking enhances the extent of DNA damage in sperm. In contrast, no significant difference was observed for conventional parameters between smokers and nonsmokers, suggesting that the level of 8-OHdG in sperm may reflect the deleterious effect of cigarette smoking on sperm quality more accurately than conventional seminal parameters. Further investigation is required to understand the exact biologic and pathologic significance of oxidative damage to sperm DNA and the possibility of using 8-OHdG for the assessment of sperm quality.

Smoking and male reproduction: a review

Because of the large number of men worldwide who smoke and the fact that cigarette smoke contains known mutagens and carcinogens, there has been concern that smoking may have adverse effects on male reproduction. A review of the epidemiological literature indicates that cigarette smoking is associated with modest reductions in semen quality including sperm concentration, motility and morphology. The associations between male smoking and sperm concentration and motility are stronger among studies of 'healthy' men (e.g. volunteers and sperm donors) than among men from infertility clinic populations. Smoking has also been associated with alterations in hormone levels in males, for example increases in the levels of oestrone and oestradiol. Despite modest reductions in semen quality and altered hormone levels among smokers compared to non-smokers, studies have not shown a reduction in male fertility in association with paternal smoking. There is some evidence to suggest that paternal smoking is associated with congenital anomalies and childhood cancer (with ORs in positive studies generally < 2.0). Smoking has not been shown to be mutagenic to human spermatozoa, although studies have been small and have had methodological shortcomings. It is concluded that, although smokers as a group may not experience reduced fertility, men with marginal semen quality who wish to have children may benefit from quitting smoking, since several small studies indicate the potential for improved semen quality after quitting smoking. More research on the benefits of quitting smoking among men with marginal semen quality is needed. Methodological improvements in studies aimed at clarifying the association between paternal smoking and reproductive and developmental outcomes in offspring should include obtaining accurate paternal smoking dose information, evaluating smoking exposure information in relation to various time windows (e.g. prior to conception, during gestation), and controlling for potential confounders and modifying factors such as age and maternal smoking habits. More sensitive and specific laboratory assays and increased sample sizes are required to establish whether smoking induces mutations in human spermatozoa.

Cigarette smoking and semen quality

OBJECTIVE

To determine whether cotinine levels provide stronger evidence for an association between smoking and semen quality than the number of cigarettes smoked per day or years smoked controlling for potential confounders and effect modifiers.

DESIGN

Cross-sectional study.

SETTING

Male volunteers at the Reproductive Endocrinology-Fertility Laboratory.

PARTICIPANTS

Eighty-eight men (ages 18 to 35 years) provided a semen, urine, and blood specimen and completed a self-administered questionnaire concerning smoking and demographic information as well as caffeine and alcohol consumption. Urine, blood, and semen cotinine levels were analyzed via RIA.

MAIN OUTCOME MEASURE

Standard clinical semen analysis.

RESULTS

Number of cigarettes smoked per day, years smoked, and log-transformed cotinine levels were associated negatively with semen quality (density, total count, and motility). The association was evident among men age > or = 22 years. For example, the correlation coefficient for the overall association between logged urine cotinine and logged sperm density was -0.23; those stratified by age were 0. 13 (age < 22 years) and - 0. 39 (age > or = 22 years). Potential confounders included in regression models did not diminish the associations.

CONCLUSIONS

Smoking is associated with lowered semen quality.

Drug monitoring in nonconventional biological fluids and matrices

Determination of the concentration of drugs and metabolites in biological fluids or matrices other than blood or urine (most commonly used in laboratory testing) may be of interest in certain areas of drug concentration monitoring. Saliva is the only fluid which can be used successfully as a substitute for blood in therapeutic drug monitoring, while an individual's past history of medication, compliance and drug abuse, can be obtained from drug analysis of the hair or nails. Drug concentrations in the bile and faeces can account for excretion of drugs and metabolites other than by the renal route. Furthermore, it is important that certain matrices (tears, nails, cerebrospinal fluid, bronchial secretions, peritoneal fluid and interstitial fluid) are analysed, as these may reveal the presence of a drug at the site of action; others (fetal blood, amniotic fluid and breast milk) are useful for determining fetal and perinatal exposure to drugs. Finally, drug monitoring in fluids such as cervical mucus and seminal fluid can be associated with morpho-physiological modifications and genotoxic effects. Drug concentration measurement in nonconventional matrices and fluids, although sometimes expensive and difficult to carry out, should therefore be considered for inclusion in studies of the pharmacokinetics and pharmacodynamics of new drugs.

Biomedical and biochemical applications of liquid chromatography-mass spectrometry

This review centres on the application of various LC-MS and LC-MS-MS techniques to the study and solution of practical problems in biomedical research. For this purpose it covers a selection of publications in this area included in the MEDLINE database for the period 1991-mid-1994. As shown herein, LC-MS is increasingly gaining in importance in the biomedical field, especially after the revolution brought about by the introduction of the new liquid-phase atmospheric pressure ionization (API) techniques, such as electrospray (ES) and ionspray. The information in this database shows that thermospray (TS), which clearly dominated LC-MS coupling in the 1980s, is on a downward trend relative to the more modern API techniques which will certainly dominate this application field in the present decade. Studies on drug metabolism, therapeutic drug monitoring and pharmacology have been traditionally carried out by GC-MS. However, LC-MS has lately been replacing classical GC-MS techniques in many of these applications. For instance, LC-ES-MS has greatly facilitated the application of both qualitative and quantitative LC-MS methods to highly polar molecules. This is possible without the need to resort to elaborate sample handling and derivatization procedures for relatively high-molecular-mass compounds such as drug conjugates, biosynthetic and natural peptides and therapeutic proteins obtained by recombinant DNA technology, all of them formerly totally inaccessible to the standard GC-MS or LC-MS methods. With regard to studies on metabolism and biochemical phenomena of endogenous compounds, LC-ES-MS is also becoming very strong in the analysis of structural biopolymers such as peptides, proteins, glycoproteins and glycolipids, and also lower molecular mass compounds such as fatty acids, vitamins, steroids and nucleic acids. For example, structural verification of post-translational modifications in proteins can be efficiently obtained in the time frame of an LC run and suitable MS methods for the location of glycopeptide-containing fractions in proteolytic digests of glycoproteins have been developed. Interesting examples are also shown of the use of LC-MS in clinical studies and the determination of biological markers of disease.

Drugs in semen

Over the past 50 years, a decline in the quality of semen has been observed, possibly resulting in a reduction in male fertility. Among the factors affecting semen quality, exposure to drugs is of particular importance. It is known that drugs can be transported to the seminal plasma, which is made up of secretions from the various accessory genital glands. There is evidence that many drugs enter the male genitourinary tract by an ion-trapping process. Lipid solubility and the degree of ionisation of the drug, which depend on the pH of plasma and seminal fluid, are important factors in this process. To date, few studies have been conducted on this topic. Pharmacokinetic evaluation of the fluids of the male accessory gland have been performed in the case of chloroquine and caffeine only, while the effects of mesalazine (5-aminosalicylic acid), sulfasalazine, salicylate, propranolol, diltiazem, flunarizine, verapamil, caffeine and nicotine on sperm physiology and morphology have been examined. Although data from the literature are scarce and incomplete, it is evident that many drugs can be excreted into semen. These drugs may interfere with the most common semen characteristics, potentially resulting in a male-mediated teratogenic effect, or local and systemic responses in female recipients. Therefore, it may be advisable to include, in the processes of drug development, pharmacokinetic evaluation of a drug in the semen and analysis of standard microscopic parameters of the semen. This is particularly important for drugs known to concentrate in the semen.