Effects of Nicotine on Human Luteal Cells In Vitro: A Possible Role on Reproductive Outcome for Smoking Women1

Consumption of hookahs, e-cigarettes, and classic cigarettes and the impact on medically assisted reproduction treatment

Smoking of classic cigarettes has been well-established as a health risk factor, including cardiovascular, neurological, and pulmonary diseases. Adverse effects on human reproduction have also been shown. Smokers are assumed to have a significantly lower chance of pregnancy, however, the impact of smoking on medically assisted reproduction (MAR) treatment outcomes is controversial. Moreover, smoking habits have changed during the last decades since e-cigarettes and hookahs, or water pipes, have become very popular, yet little is known regarding vaping or hookah-smoking patients undergoing MAR treatments. This prospective study aimed to examine the presence of benzo[a]pyrene, nicotine, and its main metabolite, cotinine, in human follicular fluid (FF) in non-smoking, smoking, and vaping/hookah-smoking patients and to evaluate the impact on female fertility. Human FF samples were collected from 320 women subjected to intracytoplasmic sperm injection (ICSI) cycles due to male subfertility. Gas chromatography combined with mass spectrometry was used to analyse the presence of benzo[a]pyrene, nicotine, and cotinine. A questionnaire was provided to assess patient consumption behaviour and to identify (1) non-smoking patients, (2) patients who consumed cigarettes, and (3) patients with exclusive consumption of e-cigarettes or hookahs. Data were analysed using linear and logistic regression, Fisher's exact test, and the Mann-Whitney U Test. Nicotine was present in 22 (6.8%) and cotinine in 65 (20.3%) of the 320 samples. The nicotine and cotinine concentrations per sample ranged from 0 to 26.3 ng/ml and 0-363.0 ng/ml, respectively. Benzo[a]pyrene was not detectable in any of the samples analysed. Nicotine and cotinine were also present in the FF of patients with exclusive consumption of e-cigarettes or hookahs. The clinical pregnancy rate, fertilization and maturation rates, and number of oocytes per oocyte pick-up were not statistically significantly different between non-smoking, smoking, or vaping/hookah-smoking patients. Smoking and the accumulation of smoking toxins in the FF have no impact on the outcome of MAR treatments-neither the clinical pregnancy rate, maturation and fertilization rates, nor the number of retrieved oocytes were affected. For the first time, nicotine and cotinine were quantified in the FF of patients exclusively vaping e-cigarettes or smoking hookahs. Since vaping liquids and hookah tobaccos contain potentially harmful substances, other adverse effects cannot be excluded.Trial registration ClinicalTrials.gov Identifier: NCT03414567.

Premature ovarian insufficiency: a review on the role of tobacco smoke, its clinical harm, and treatment

Premature ovarian insufficiency (POI) is a condition in which the quantity of follicles and the quality of oocytes gradually decrease. This results in an estrogen secretion disorder and abnormal follicle development, which can lead to related diseases, early onset of menopause, sexual dysfunction, and an increased risk of cardiovascular issues, osteoporosis, and depression, among others. This disease significantly impacts the physical and mental health and overall quality of life of affected women. Factors such as genetic abnormalities, oophorectomy, radiotherapy for malignancy, idiopathic conditions, and an unhealthy lifestyle, including smoking, can accelerate the depletion of the follicular pool and the onset of menopause. Extensive research has been conducted on the detrimental effects of tobacco smoke on the ovaries. This article aims to review the advancements in understanding the impact of tobacco smoke on POI, both in vivo and in vitro. Furthermore, we explore the potential adverse effects of common toxicants found in tobacco smoke, such as polycyclic aromatic hydrocarbons (PAHs), heavy metals like cadmium, alkaloids like nicotine and its major metabolite cotinine, benzo[a]pyrene, and aromatic amines. In addition to discussing the toxicants, this article also reviews the complications associated with POI and the current state of research and application of treatment methods. These findings will contribute to the development of more precise treatments for POI, offering theoretical support for enhancing the long-term quality of life for women affected by this condition.

Endometriosis and environmental factors: a critical review

This review provides an overview of current knowledge on the relationship between various environmental factors and endometriosis. We successively searched for a given exposure factor combined with the word "endometriosis." The literature was comprehensively analyzed and summarized by quoting only the most important and recent studies on each exposition factor. The data focused primarily on endocrine disruptors, such as dioxins and polychlorinated biphenyls, that appear to have the strongest effect. Intriguing data suggest a link with night work, sun exposure and red meat consumption. For the other risk factors studied, particularly those related to lifestyle (tobacco consumption, alcohol, coffee, soy, physical exercise), the data are not sufficient to draw conclusions. In summary, the epidemiological evidence does not support a strong, scientific link between exposure to environmental factors and endometriosis. The complexity of this disease requires advanced study designs and standardized methodology. Future studies should be carefully designed to address these issues to advance our understanding of the impact of the environment and its consequences on endometriosis.

Tobacco carcinogen 4-[methyl(nitroso)amino]-1-(3-pyridinyl)-1-butanone (NNK) drives metabolic rewiring and epigenetic reprograming in A/J mice lung cancer model and prevention with diallyl sulphide (DAS)

Early detection of biomarkers in lung cancer is one of the best preventive strategies. Although many attempts have been made to understand the early events of lung carcinogenesis including cigarette smoking (CS) induced lung carcinogenesis, the integrative metabolomics and next-generation sequencing approaches are lacking. In this study, we treated the female A/J mice with CS carcinogen 4-[methyl(nitroso)amino]-1-(3-pyridinyl)-1-butanone (NNK) and naturally occurring organosulphur compound, diallyl sulphide (DAS) for 2 and 4 weeks after NNK injection and examined the metabolomic and DNA CpG methylomic and RNA transcriptomic profiles in the lung tissues. NNK drives metabolic changes including mitochondrial tricarboxylic acid (TCA) metabolites and pathways including Nicotine and its derivatives like nicotinamide and nicotinic acid. RNA-seq analysis and Reactome pathway analysis demonstrated metabolism pathways including Phase I and II drug metabolizing enzymes, mitochondrial oxidation and signaling kinase activation pathways modulated in a sequential manner. DNA CpG methyl-seq analyses showed differential global methylation patterns of lung tissues from week 2 versus week 4 in A/J mice including Adenylate Cyclase 6 (ADCY6), Ras-related C3 botulinum toxin substrate 3 (Rac3). Oral DAS treatment partially reversed some of the mitochondrial metabolic pathways, global methylation and transcriptomic changes during this early lung carcinogenesis stage. In summary, our result provides insights into CS carcinogen NNK's effects on driving alterations of metabolomics, epigenomics and transcriptomics and the chemopreventive effect of DAS in early stages of sequential lung carcinogenesis in A/J mouse model.

Toxic effects of smokeless tobacco on female reproductive health: A review

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Smokeless tobacco use can lead to impairments of ovarian function, morphology, oocyte quality and hormonal regulation.

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Use of smokeless tobacco during pregnancy has adverse health effects on both the mother and fetus.

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Exposure to smokeless tobacco in utero has long term health consequences on offspring.

The habitual consumption of tobacco in its various form is widespread and a serious public health issue globally. In particular, the use of smokeless tobacco has increased substantially due to its easy availability and misconception that it is relatively harmless compared to smoking. Tobacco use has been well established from numerous studies as a causative agent of devastating illnesses such as cancer, insulin resistance, hypertension, acute respiratory disease, osteoporosis, etc. Limited but growing evidence have also suggested its role in adversely affecting reproductive capabilities and outcomes in women of reproductive age and during pregnancy. This paper provides an updated review on available literature regarding the negative effects of smokeless tobacco use on female reproductive health, during pregnancy and its adverse consequences on the offspring. Existing data suggests the association between chronic smokeless tobacco use and impairment of ovarian morphology and function, oocyte quality, hormonal perturbations, fetal development and long-term health effects on the fetus. Improved understanding of these issues can contribute to better awareness of the dangers of smokeless tobacco products.

Ginseng alleviates folliculogenesis disorders via induction of cell proliferation and downregulation of apoptotic markers in nicotine-treated mice

Background

Ginseng is a powerful phytoestrogen with high antioxidant properties.

Objective

This study aimed to evaluate the effect of Panax Ginseng (PG) on folliculogenesis, proliferation, and apoptosis in the ovary impaired by nicotine.

Methods

Forty adult mice were divided into five groups. Control, sham, and nicotine groups, and co-treated groups of nicotine and ginseng in doses of 0.5 and 1 g/kg. Folliculogenesis was assessed via histopathology and serum evaluation of estradiol, progesterone, follicle-stimulating hormone (FSH), and luteinizing hormone (LH) by ELISA. Lipid peroxidation and antioxidant enzyme activities both in homogenate tissue and serum were assayed by colorimetric analysis. Apoptotic markers of cytochrome c (Cyt c), Bax, and Bcl-2 were evaluated by RT-PCR. Proliferative index was studied by the Ki-67 immunostaining procedure.

Results

In comparison to the control or sham groups, nicotine significantly reduced the levels of FSH, LH, and estradiol hormones. An insignificant reduction was observed in the progesterone hormone. Nicotine reduced all healthy follicle numbers, except primordial (P = 0.001). Malondialdehyde (MDA) was increased in tissue and serum in the nicotine group (P = 0.01). Serum catalase (CAT) and enzymatic activity of superoxide dismutase (SOD) both were reduced in tissue and the serum, in the nicotine group. Nicotine induced a reduction in the proliferative indexes of granulosa and theca cells in pre-antral and antral follicles (P = 0.001). However, its effect on the proliferative index of stroma cells was not significant. Apoptotic markers were elevated in the nicotine group (P = 0.001). Co-treatment with ginseng elevated all sex hormones, increased healthy follicles, and reduced tissue or serum lipid peroxidation, compared with the nicotine group (p < 0.05). Co-Treatment with ginseng also reduced the expression of apoptotic markers and increased the proliferative indexes in granulosa and theca cells in pre-antral and antral follicles and also in stroma cells, in comparison to the nicotine group (P = 0.001). All above-mentioned alterations following treatment with ginseng were remarkable, especially in the dose of 1 g/kg.

Conclusion

This study showed ginseng protects folliculogenesis via alteration of hypothalamic- pituitary–gonadal (HPG) axis, induction of proliferation in ovarian somatic cells, reduction of lipid peroxidation, and downregulation of apoptotic markers in the mouse ovary, treated with nicotine.

Pathophysiological effects of cadmium(II) on human health-a critical review

Cadmium(II) is an omnipresent environmental toxicant emitted from various industrial sources and by anthropogenic sources such as smoking. Cadmium(II) enters our body through various sources including contaminated food and drinks and from active or passive smoking. It spares no organs in our body and the calamities it invites include primarily nephrotoxicity, osteotoxicity, teratogenicity, endocrine disruption, hepatotoxicity and carcinogenicity above all. It brings about a bolt from the blue in the cellular biochemistry by generating reactive oxygen species (ROS), disrupting the factors involved in the repair of DNA lesions and many other toxic nuisances otherwise by modulating the cell signalling machinery and acting as a potent carcinogen above all. In this review, we have tried to decipher some of the mechanisms played by cadmium(II) in exhibiting its toxic effects on various system of our body.

Looking Inside the World of Granulosa Cells: The Noxious Effects of Cigarette Smoke

The detrimental implications of tobacco smoke on systemic health have been widely established during the past few decades. Nonetheless, increasing evidence has begun to shed more light on the serious impact that smoke exposure could also have on mammal reproductive health in terms of overall ovarian dysfunction and gestation. A variety of these complications seem to be causally related to specific chemical substances contained in cigarette smoke and their possible effects on ovarian tissues and cells, such as granulosa cells. Granulosa cells represent the functional unit of the ovary and are able to establish a bidirectional cross-talk relationship with the oocyte during folliculogenesis, which makes them vital for its correct growth and development. Based on these premises, the current review focuses on the presence of related smoke-induced damages in granulosa cells. Data have been grouped according to the studied tobacco constituents and the molecular pathways involved, in order to synthesize their impact on granulosa cells and fertility. Attention is further brought to the correlation between electronic cigarettes and female reproduction, although there have been no investigations so far regarding e-cigarette-related granulosa cell exposure. We summarize how tobacco constituents are able to cause alterations in the "life" of granulosa cells, ranging from luteal steroidogenesis and follicular loss to granulosa cell apoptosis and activation of the autophagic machinery. Further studies have been conducted to elucidate the relationship between lifestyle and fertility as to reduce the morbidity connected with infertility.

Nicotine-Induced Oxidative Stress in Human Primary Endometrial Cells

Nicotine is a major component of tobacco plants and is responsible for the development of reproductive problems in smokers. Nicotine has been recognized to result in oxidative stress by inducing the generation of reactive oxygen species (ROS) in some parts of female reproductive system, but the effect of nicotine on endometrium that plays an important role in reproductive biology stays unexplored. The aim of this work was to clarify the direct effects of nicotine administration on the antioxidant defense system and lipid peroxidation in human endometrial cells. Human endometrial stromal primary cells were treated with nicotine (0, 10−11, 10−8, and 10−6 M) for 24 hours. On nicotine administration, the endometrial cells were associated with a decrease in antioxidant defense markers such as Glutathione (GSH) level, glutathione peroxidase (GPx), glutathione reductase (GR), and catalase (CAT) enzymes activity and higher levels of malondialdehyde (MDA) in a dose-dependent manner when compared to the control. We concluded that nicotine as a pro-oxidant affects the oxidative state of the endometrial cells.

Prospective evaluation of luteal phase length and natural fertility

OBJECTIVE

To evaluate the impact of a short luteal phase on fecundity.

DESIGN

Prospective time-to-pregnancy cohort study.

SETTING

Not applicable.

PATIENT(S)

Women trying to conceive, ages 30-44 years, without known infertility.

INTERVENTION(S)

Daily diaries, ovulation prediction testing, standardized pregnancy testing.

MAIN OUTCOME MEASURE(S)

Subsequent cycle fecundity.

RESULT(S)

Included in the analysis were 1,635 cycles from 284 women. A short luteal phase (≤11 days including the day of ovulation) occurred in 18% of observed cycles. Mean luteal phase length was 14 days. Significantly more women with a short luteal phase were smokers. After adjustment for age, women with a short luteal phase had 0.82 times the odds of pregnancy in the subsequent cycle immediately following the short luteal phase compared with women without a short luteal phase. Women with a short luteal length in the first observed cycle had significantly lower fertility after the first 6 months of pregnancy attempt, but at 12 months there was no significant difference in cumulative probability of pregnancy.

CONCLUSION(S)

Although an isolated cycle with a short luteal phase may negatively affect short-term fertility, incidence of infertility at 12 months was not significantly higher among these women.

CLINICAL TRIAL REGISTRATION NUMBER

NCT01028365.

Tobacco smoking and risk of endometriosis: a systematic review and meta-analysis

OBJECTIVE

Since conflicting results have been published on the role of tobacco smoking on the risk of endometriosis, we provide an up-to-date summary quantification of this potential association.

DESIGN

We performed a PubMed/MEDLINE search of the relevant publications up to September 2014, considering studies on humans published in English. We searched the reference list of the identified papers to find other relevant publications. Case-control as well as cohort studies have been included reporting risk estimates on the association between tobacco smoking and endometriosis. 38 of the 1758 screened papers met the inclusion criteria. The selected studies included a total of 13,129 women diagnosed with endometriosis.

SETTING

Academic hospitals.

MAIN OUTCOME MEASURE

Risk of endometriosis in tobacco smokers.

RESULTS

We obtained the summary estimates of the relative risk (RR) using the random effect model, and assessed the heterogeneity among studies using the χ(2) test and quantified it using the I(2) statistic. As compared to never-smokers, the summary RR were 0.96 (95% CI 0.86 to 1.08) for ever smokers, 0.95 (95% CI 0.81 to 1.11) for former smokers, 0.92 (95% CI 0.82 to 1.04) for current smokers, 0.87 (95% CI 0.70 to 1.07) for moderate smokers and 0.93 (95% CI 0.69 to 1.26) for heavy smokers.

CONCLUSIONS

The present meta-analysis provided no evidence for an association between tobacco smoking and the risk of endometriosis. The results were consistent considering ever, former, current, moderate and heavy smokers, and across type of endometriosis and study design.

Cellular mechanisms of cadmium-induced toxicity: a review

Cadmium is a widespread toxic pollutant of occupational and environmental concern because of its diverse toxic effects: extremely protracted biological half-life (approximately 20-30 years in humans), low rate of excretion from the body and storage predominantly in soft tissues (primarily, liver and kidneys). It is an extremely toxic element of continuing concern because environmental levels have risen steadily due to continued worldwide anthropogenic mobilization. Cadmium is absorbed in significant quantities from cigarette smoke, food, water and air contamination and is known to have numerous undesirable effects in both humans and animals. Cadmium has a diversity of toxic effects including nephrotoxicity, carcinogenicity, teratogenicity and endocrine and reproductive toxicities. At the cellular level, cadmium affects cell proliferation, differentiation, apoptosis and other cellular activities. Current evidence suggests that exposure to cadmium induces genomic instability through complex and multifactorial mechanisms. Most important seems to be cadmium interaction with DNA repair mechanism, generation of reactive oxygen species and induction of apoptosis. In this article, we have reviewed recent developments and findings on cadmium toxicology.

Active and passive smoking and fecundability in Danish pregnancy planners

OBJECTIVE

To investigate the extent to which fecundability is associated with active smoking, time since smoking cessation, and passive smoking.

DESIGN

Prospective cohort study.

SETTING

Denmark, 2007-2011.

PATIENT(S)

A total of 3,773 female pregnancy planners aged 18-40 years.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Self-reported pregnancy. Fecundability ratios (FRs) and 95% confidence intervals (CIs) were estimated using a proportional probabilities model that adjusted for menstrual cycle at risk and potential confounders.

RESULT(S)

Among current smokers, smoking duration of ≥10 years was associated with reduced fecundability compared with never smokers (FR, 0.85, 95% CI 0.72-1.00). Former smokers who had smoked ≥10 pack-years had reduced fecundability regardless of when they quit smoking (1-1.9 years FR, 0.83, 95% CI 0.54-1.27; ≥2 years FR, 0.73, 95% CI 0.53-1.02). Among never smokers, the FRs were 1.04 (95% CI 0.89-1.21) for passive smoking in early life and 0.92 (95% CI 0.82-1.03) for passive smoking in adulthood.

CONCLUSION(S)

Among Danish pregnancy planners, cumulative exposure to active cigarette smoking was associated with delayed conception among current and former smokers. Time since smoking cessation and passive smoking were not appreciably associated with fecundability.

Nicotine and endometrial decidual growth in pseudopregnant rats

Purpose

The present study aims to investigate the effects of nicotine on the endometrial decidual growth and levels of estrogen and progesterone in pseudopregnant rats.

Methods

Pseudopregnancy (pc) was induced in cyclic Sprague-Dawley rats by sterile mating. Subcutaneous injection of nicotine tartrate (7.5 mg/kg/day) was scheduled from day 1 through day 5, day 5 through day 9 or day 1 through day 9 of pc. In another group of pseudopregnant rats, concomitant treatment of nicotine tartrate concurrently with progesterone (2 mg/day) was scheduled from day 1 through day 9 pc. Control groups received subcutaneous injections of vehicle only. Endometrial decidualization was induced on day 5 pc. On day 10 pc, animals were sacrificed.The degree of decidual growth and circulating levels of estrogen and progesterone were measured.

Results

The decidual growth in all the first three nicotine-treated groups of animals was significantly reduced, particularly in the animals treated with nicotine from day 1 through day 9 pc. Plasma estrogen levels were significantly elevated in animals treated with nicotine from day 1 through day 9 pc. Conversely, levels of plasma progesterone were found to be significantly attenuated in the same group of nicotine-treated animals compared to controls. Exogenous replacement of progesterone, however, caused a higher degree of endometrial decidualization compared to the nicotine-treated group but it was slightly less than when compared to control.

Conclusions

In conclusion, nicotine-induced progesterone deficiency with a corresponding elevation of estrogen may possibly attenuate the degree of endometrial decidualization in pseudopregnant rats.

Cigarette smoke condensate exposure delays follicular development and function in a stage-dependent manner

OBJECTIVE

To determine the effects of cigarette smoke condensate (CSC) on follicular development and function from the early preantral stage through ovulation.

DESIGN

Prospective laboratory study.

SETTING

Academic research environment.

ANIMAL(S)

Female F1 hybrid (C57BL/6j×CBA/Ca) mice.

INTERVENTION(S)

Mouse early preantral follicles (100-130 μm) were exposed to increasing concentrations of CSC (0 μg/mL [control] to 130 μg/mL) during in vitro growth and ovulation.

MAIN OUTCOME MEASURE(S)

Follicular development, follicle survival, gonadal steroid output, expansion of the cumulus-oocyte complex, oocyte growth, and maturation.

RESULT(S)

Cigarette smoke condensate exposure significantly inhibited follicular development in the preantral and antral stage and decreased follicle survival at 90 μg CSC/mL and higher. Estradiol output was significantly lower in CSC-exposed (90 and 130 μg/mL) follicles. Before ovulation, CSC significantly increased P output, which decreased thereafter. Cigarette smoke condensate exposure reduced cumulus-oocyte complex expansion and subsequently reduced the number of polar body oocytes.

CONCLUSION(S)

Cigarette smoke condensate exposure inhibits follicle development and leads to premature luteinization of the preovulatory follicle, with decreased oocyte maturation in a mouse isolated follicle culture system that mimics murine folliculogenesis in vivo.

Nicotine potentiates vascular endothelial growth factor expression in balloon-injured rabbit aortas

Both nicotine and vascular endothelial growth factor (VEGF) have been proposed to play an important role in the development and progression of atherosclerosis. In vitro and ex vivo studies have demonstrated that nicotine significantly stimulates VEGF expression in several cell types. This study examined the effects and the mechanisms of nicotine on the expression of VEGF in a rabbit model of balloon-injured aortas. Forty-eight male New Zealand white rabbits were randomly divided into sham, control, nicotine, and nicotine plus hexamethonium (nicotine-hex) groups. Balloon catheter denuding injury iliac artery was performed in control, nicotine, and nicotine-hex animals fed with a high-cholesterol diet beginning 2 weeks before operation. Twenty-four hours after surgery, nicotine (0.05 microg/kg) or nicotine (0.05 microg/kg) and hexamethonium (6 mg/kg) was administered daily by intramuscular injection for 3 weeks in nicotine and nicotine-hex groups, respectively. Sham and control rabbits received an identical volume of phosphate-buffered saline injection, but without nicotine or hexamethonium. VEGF protein expression and intimal cell proliferation in balloon-injured aortas were determined by enzyme-link immunosorbent assay, immunohistochemistry, and Western blot analysis. Six rabbits died during the experiment. The remaining 42 rabbits were included in the study. VEGF protein expression in nicotine group was significantly higher than that in control group (P < 0.01). VEGF positive staining was seen in vascular endothelial cells, vascular smooth muscle cells, and infiltrative inflammatory cells. The number of the proliferative cells in intima was also significantly higher in nicotine group than in control group (P < 0.01). Hexamethonium, a nonselective antagonist of nicotinic acetylcholine receptors (nAChRs), significantly inhibited nicotine-induced VEGF protein expression (P < 0.01). The present study shows that intramuscular administration of nicotine markedly potentiates the expression of VEGF protein in balloon-injured rabbit aortas, which appears to be mediated through nAChRs.

Nicotine induces multinuclear formation and causes aberrant embryonic development in bovine

The present study was designed to investigate the effects of nicotine on development of bovine embryos derived from parthenogenetic activation (PA) and in vitro fertilization (IVF). Nicotine caused disfigured secondary meiotic spindle structures and affected embryonic development in a dose-dependent manner. Concentrations at 0.01-0.5 mM resulted in cleavage and blastocyst rates similar to the controls for both PA and IVF embryos. Nicotine at 2.0 and 4.0 mM significantly decreased the cleavage rates and none of the embryos developed beyond the 16-cell stage. Nicotine might disrupt the polymerization of microfilaments leading to impaired chromosome alignment or segregation, and induce the formation of polynuclei with a variety of abnormal nuclear structures such as 2-6 nuclei, 2-4 metaphase plates, 2-4 sets of anaphase/telophase plates, and the co-existence of polynuclei and 2-4 sets of anaphase/telophase plates. Nicotine adversely affected blastocyst chromosomal composition. Fifty-six to 70% of the IVF blastocysts and 71-88% of the PA blastocysts were polyploid and/or mixoploid after culture in 0.2-1.0 mM nicotine-containing media, which were higher (P < 0.05 or P < 0.01) than the controls. Cell numbers of the nicotine-cultured blastocysts were significantly lower than the control. In conclusion, nicotine induced disfigured spindles and irregular chromosome alignment and possibly impaired cytokinesis, which lead to decreased quality of the yielded blastocysts.

Cigarette smoking and reproductive function

PURPOSE OF REVIEW

To perform a systematic review of the literature on the relationship between cigarette smoking and reproductive function. Whenever possible, this review is focused on the most recently published studies (mainly the past 2 years). Nevertheless, in many instances older literature was too relevant not to be taken into account.

RECENT FINDINGS

Tobacco compounds exert a deleterious effect on the process of ovarian follicle maturation. This effect is expressed by worse in-vitro fertilization parameters in cycles performed on women with smoking habits. Also, uterine receptiveness is significantly altered by the smoking habit. In men, cigarette smoking reduces sperm production, increases oxidative stress, and DNA damage. Spermatozoa from smokers have reduced fertilizing capacity, and embryos display lower implantation rates. Even in-utero exposition to tobacco constituents leads to reduced sperm count in adult life.

SUMMARY

A strong body of evidence indicates that the negative effect of cigarette smoking on fertility comprises fairly every system involved in the reproductive process. Couples in reproductive age should be strongly discouraged to smoke.

Effect of nicotine on in vitro maturation of bovine oocytes

The putative effect of nicotine on maturation and the chromosomal complement of bovine oocytes were investigated in the present study. Cumulus-enclosed oocytes were incubated in maturation medium with 0, 0.5, 1.0, 2.5, 5.0, and 10.0 mmol concentrations of nicotine. The results indicated that: (1) nicotine affected cumulus cell expansion in a dose-dependent manner and the perivitelline space failed to form when concentrations were equal to or greater than 5.0 mmol; (2) oocytes treated with 0.5 and 1.0 mmol nicotine concentrations resulted in maturation rates (83.3% and 85.9%, respectively) which was similar to the control (86.2%), whereas treatment with 2.5 and 5.0 mmol concentrations significantly decreased maturation rates to 70.2% and 26.7%, respectively; (3) nicotine at or over 2.5 mmol caused extremely irregular meiotic spindles and interrupted microfilament organization; (4) chromosomal analyses of oocytes with PB1 showed that oocytes derived from 0.5 and 1.0 mmol nicotine groups had haploid complements similar to the control (87-90%), but when the concentrations were increased to 2.5 and 5.0 mmol the haploid state was significantly reduced to around 70%; (5) oocytes at GVBD (germinal vesicle breakdown) and metaphase I stages were less affected by nicotine at 5.0 and 10.0 mmol concentrations than GV-stage oocytes; (6) maturation rates of the short-term nicotine-treated oocytes could be improved when subsequently incubated in normal maturation medium. Prolonged culture of nicotine-pretreated oocytes resulted in self-activation and some oocytes formed 1 or 2 pronuclei. In conclusion, nicotine affects bovine oocyte cumulus cell expansion, maturation rate, and chromosomal complement in a dose-dependent and an oocyte-stage-dependent manner.

Nicotine alters bovine oocyte meiosis and affects subsequent embryonic development

The effects of nicotine on nuclear maturation and meiotic spindle dynamics of bovine oocytes and subsequent embryonic development were investigated. Maturation rates (85%-94%) derived from nicotine treatments at 0.01 to 1.0 mM were similar to the control (86%), but significantly decreased at 2.0 to 6.0 mM. Haploid complements of metaphase II oocytes in 0.01 to 1.0 mM nicotine (approximately 90%) were similar to the control, while lower (ranged from 63% to 76%, P < 0.05 or P < 0.01) haploid oocytes were observed in the 2.0 to 6.0 mM nicotine groups. The majority of the PB1-free oocytes derived from 3.0 to 6.0 mM nicotine treatments were diploidy (2n = 60). Spindle microtubules changed from characteristically being asymmetrical in the controls to being equally distributed into two separate chromosome groups in the nicotine treatments. Nicotine disorganized the microfilament organization and inhibited the movement of anaphase or telophase chromosomes to the cortical area. The inhibited two chromosome groups became two spindles that either moved close in proximity or merged entirely together resulting in diploidy within the affected oocyte. Nicotine treatment significantly reduced the rate of cleavage and blastocyst development after parthenogenetic activation. Diploidy and cell number were drastically reduced in the resultant blastocysts. In conclusion, nicotine can alter the normal process of bovine oocyte meiosis and affects subsequent embryonic development.

Nicotine-induced prenatal overexposure to maternal glucocorticoid and intrauterine growth retardation in rat

Overexposure to glucocorticoid during fetal development can result in intrauterine growth retardation (IUGR) as well as other diseases after birth. The purpose of this study is to investigate the possibility of glucocorticoid disturbance-mediated nicotine-induced IUGR after chronic prenatal exposure. Nicotine at 1.0mg/kg twice a day was administered subcutaneously to pregnant rats from gestational day (GD) 8 to GD 15 (mid-gestation) or GD 21 (late-gestation). Placental weights and fetal developmental parameters were recorded. Corticosterone levels were determined by radioimmunoassay. The mRNA expressions of adrenal steroidogenic acute regulatory protein (StAR), cytochrome P450 cholesterol side chain cleavage (P450scc) and placental 11 beta-hydroxysteroid dehydrogenase type 2 (11 beta-HSD-2) were determined using real-time quantitative RT-PCR. The results showed that prenatal chronic nicotine exposure causes IUGR in rats (P<0.01); in response to nicotine exposure, maternal serum corticosterone levels were elevated at mid- and late-gestations (P<0.05); mRNA expressions of StAR and P450scc increased in maternal adrenals (P<0.05 or 0.01) but decreased in fetal adrenals (P=0.16 or 0.11). Furthermore, the mRNA levels of placental 11 beta-HSD-2 were reduced at mid- and late-gestations (P<0.05). These results suggest that nicotine-induced IUGR is associated with the disturbances of glucocorticoid homeostasis in maternal and fetal rats. A possible underlying mechanism is that long term nicotine administration leads to fetal overexposure to maternal glucocorticoid by the combined effect of increased maternal glucocorticoid level and impaired placental barrier to it, all of which eventually leads to the fetal adrenocortical dysfunction and IUGR.

Hormonal changes accompanying cigarette smoke-induced preterm births in a mouse model

Epidemiologic evidence indicates that maternal smoking increases the risk of preterm birth. While a number of plausible mechanisms for early delivery have been offered, the role of gestational hormones in this smoke-induced outcome is uncertain. Thus, a toxicologic study was performed to examine the effects and underlying hormonal mechanisms of mainstream cigarette smoke (MCS) exposure on gestational duration. Pregnant B6C3F1 mice were exposed by inhalation to MCS for 5 days/week (4 hrs/day) from Gestational Day (GD) 4 to parturition. Smoke-induced effects on gestational length, interpubic ligament length, maternal hormone secretion patterns (estradiol-17beta, progesterone, prolactin, and relaxin), body weight gain, postimplantation loss, litter size, and offspring sex ratio were examined. Dams exposed to MCS at a concentration equivalent to smoking less than one pack of cigarettes/day (carbon monoxide = 25 parts per million, total suspended particulates = 16 mg/m3) demonstrated a significant (P < 0.05) shortening of gestational duration (compared with pregnant, air-exposed mice). In addition, MCS-exposed mice sacrificed on GD 18 had significantly (P < 0.05) increased interpubic ligament length, elevated serum estrogen levels, and a reduced progesterone to estradiol-17beta ratio (compared with air-exposed controls); levels of progesterone and prolactin were only modestly decreased and increased, respectively, in the MCS-exposed mice. Smoke exposure had no significant effects on maternal relaxin levels, body weight gain, postimplantation loss, litter size, or sex ratio. Results of this study demonstrate that inhalation exposure of pregnant mice to a low dose of MCS shortens gestation and alters hormone secretory patterns, which are important for maintaining pregnancy and inducing parturition. These findings support the view that pregnant women who smoke (even modestly) may be at increased risk for preterm birth, and that early delivery may be related (at least partly) to MCS-induced.

Fetal and neonatal exposure to nicotine disrupts ovarian function and fertility in adult female rats

Women born to mothers who smoked during pregnancy have been shown to have impaired fertility, although the mechanisms underlying this association are unknown. Nicotine administration in adult animals has adverse effects on the ovary and uterus; however, the effects of fetal exposure to nicotine on postnatal ovarian function have not been determined. The goal of this study was to assess the effect of fetal and neonatal exposure to nicotine on ovarian function and fertility of the offspring. Nulliparous female Wistar rats were given 1 mg.kg-1.d-1 nicotine bitartrate, subcutaneously for 14 d prior to mating, during pregnancy and throughout lactation until weaning. Measures of fertility, breeding success, and serum levels of ovarian steroid hormones in offspring were assessed at 4 and 6 mo of age. Fetal and neonatal exposure to nicotine significantly increased the time to pregnancy as the animals aged. Similarly, evidence of altered ovarian steroidogenesis including increased serum progesterone concentrations and a decreased estrogen:progesterone ratio was observed in 6-mo-old animals. We conclude that fetal and neonatal exposure to nicotine results in delayed ovarian dysfunction in adult female offspring.

Smoking impairs angiogenesis during maturation of human oocytes

OBJECTIVE

This study determines whether smoking influences ovarian vascularization which thus may impair follicular development.

DESIGN

Prospective laboratory study of follicular fluids and granulosa cells from patients undergoing in vitro fertilization.

SETTING

University Hospital Aachen, Germany.

PATIENT(S)

Fifty smoking women and 50 nonsmoking women.

INTERVENTION(S)

Cultivation of human granulosa cells. Cultivation of human umbilical vein endothelial cells (HUVECs) with either granulosa cell-conditioned medium or follicular fluid. Determination of clinical parameters.

MAIN OUTCOME MEASURE(S)

Quantification of soluble vascular endothelial growth factor receptor 1 (sVEGFR-1) and cotinine.

RESULT(S)

Mean sVEGFR-1 concentration in follicular fluid of smokers was 499.6 pg/mL compared with 159.2 pg/mL in nonsmokers. Correspondingly, supernatant of HUVECs cultured with follicular fluid from smoking and nonsmoking women showed, respectively, 1,174.1 pg/mL versus 794.2 pg/mL sVEGFR-1. The HUVECs incubated with conditioned medium from smokers' granulosa cells at culturing days 5, 9, 13, and 17 secreted, respectively, 1,712.4, 1,560.6, 1,619.0, and 1,635.0 pg/mL sVEGFR-1, whereas nonsmokers showed, respectively, 1,147.6, 1,067.2, 1,135.9, and 1,206.3 pg/mL sVEGFR-1. Mean cotinine concentration in smoking women was 83.9 ng/mL and in nonsmoking was 2.8 ng/mL. In all four comparisons, differences between groups reached statistical significance.

CONCLUSION(S)

This study showed that smokers secrete significantly higher amounts of sVEGFR-1 than nonsmokers, which may result in decreased ovarian vascularization and reduced oocyte maturation.

Cigarette smoking and effects on hormone function in premenopausal women

Cigarette smoke contains compounds that are suspected to cause reproductive damage and possibly affect hormone activity; therefore, we examined hormone metabolite patterns in relation to validated smoking status. We previously conducted a prospective study of women of reproductive age (n = 403) recruited from a large health maintenance organization, who collected urine daily during an average of three to four menstrual cycles. Data on covariates and daily smoking habits were obtained from a baseline interview and daily diary, and smoking status was validated by cotinine assay. Urinary metabolite levels of estrogen and progesterone were measured daily throughout the cycles. For the present study, we measured urinary levels of the pituitary hormone follicle-stimulating hormone (FSH) in a subset of about 300 menstrual cycles, selected by smoking status, with the time of transition between two cycles being of primary interest. Compared with nonsmokers, moderate to heavy smokers (>/= 10 cigarettes/day) had baseline levels (e.g., early follicular phase) of both steroid metabolites that were 25-35% higher, and heavy smokers (>/= 20 cigarettes/day) had lower luteal-phase progesterone metabolite levels. The mean daily urinary FSH levels around the cycle transition were increased at least 30-35% with moderate smoking, even after adjustment. These patterns suggest that chemicals in tobacco smoke alter endocrine function, perhaps at the level of the ovary, which in turn effects release of the pituitary hormones. This endocrine disruption likely contributes to the reported associations of smoking with adverse reproductive outcomes, including menstrual dysfunction, infertility, and earlier menopause.