The effects of cigarette smoke extract on ovulation, oocyte morphology and ovarian gene expression in mice

Use of cigarettes and heated tobacco products during pregnancy and maternal-fetal outcomes: a retrospective, monocentric study

PURPOSE

To compare the effects of using heated tobacco products (HTP) or traditional cigarettes (C) on maternal and neonatal outcomes.

METHODS

This is a retrospective, monocentric study conducted at San Marco Hospital from July 2021 to July 2022. We compared a cohort of pregnant patients who smoked HTP (HS), with pregnant women smoking cigarettes (CS), ex-smoker (ES) and non-smoker (NS) pregnant women. Biochemistry, ultrasound, and neonatal evaluations were performed.

RESULTS

In total, 642 women were enrolled, of which 270 were NS, 114 were ES, 120 were CS, and 138 were HS. CS had the greatest weight gain and had more difficulty getting pregnant. Smokers and ES experienced more frequently threats of preterm labor, miscarriages, temporary hypertensive spikes, and higher rates of cesarean sections. Preterm delivery was more associated with CS and HS groups. CS and HS had lower awareness of the risks to which the mother and the fetus are exposed. CS were more likely to be depressed and anxious. Biochemical parameters did not show significant differences between the groups. CS had the greatest difference in days between the gestational age calculated based on the last menstrual period and the one based on the actual ultrasound age. The average percentile newborn weight range of CS was lower, as well as the mean 1st minute and the 5th minute Apgar scores.

CONCLUSION

The comparison of the data obtained between CS and HS underlines the greater danger of C. Nevertheless, we do not recommend HTP because the maternal-fetal outcomes are not superimposable to the NS outcomes.

Transcriptomic integrity of human oocytes used in ARTs: technical and intrinsic factor effects

BACKGROUND

Millions of children have been born throughout the world thanks to ARTs, the harmlessness of which has not yet been fully demonstrated. For years, efforts to evaluate the specific effects of ART have focused on the embryo; however, it is the oocyte quality that mainly dictates first and foremost the developmental potential of the future embryo. Ovarian stimulation, cryopreservation, and IVM are sometimes necessary steps to obtain a mature oocyte, but they could alter the appropriate expression of the oocyte genome. Additionally, it is likely that female infertility, environmental factors, and lifestyle have a significant influence on oocyte transcriptomic quality, which may interfere with the outcome of an ART attempt.

OBJECTIVE AND RATIONALE

The objective of this review is to identify transcriptomic changes in the human oocyte caused by interventions specific to ART but also intrinsic factors such as age, reproductive health issues, and lifestyle. We also provide recommendations for future good practices to be conducted when attempting ART.

SEARCH METHODS

An in-depth literature search was performed on PubMed to identify studies assessing the human oocyte transcriptome following ART interventions, or in the context of maternal aging, suboptimal lifestyle, or reproductive health issues.

OUTCOMES

ART success is susceptible to external factors, maternal aging, lifestyle factors (smoking, BMI), and infertility due to endometriosis or polycystic ovary syndrome. Indeed, all of these are likely to increase oxidative stress and alter mitochondrial processes in the foreground. Concerning ART techniques themselves, there is evidence that different ovarian stimulation regimens shape the oocyte transcriptome. The perturbation of processes related to the mitochondrion, oxidative phosphorylation, and metabolism is observed with IVM. Cryopreservation might dysregulate genes belonging to transcriptional regulation, ubiquitination, cell cycle, and oocyte growth pathways. For other ART laboratory factors such as temperature, oxygen tension, air pollution, and light, the evidence remains scarce. Focusing on genes involved in chromatin-based processes such as DNA methylation, heterochromatin modulation, histone modification, and chromatin remodeling complexes, but also genomic imprinting, we observed systematic dysregulation of such genes either after ART intervention or lifestyle exposure, as well as due to internal factors such as maternal aging and reproductive diseases. Alteration in the expression of such epigenetic regulators may be a common mechanism linked to adverse oocyte environments, explaining global transcriptomic modifications.

WIDER IMPLICATIONS

Many IVF factors and additional external factors have the potential to impair oocyte transcriptomic integrity, which might not be innocuous for the developing embryo. Fortunately, it is likely that such dysregulations can be minimized by adapting ART protocols or reducing adverse exposure.

Fertility loss: negative effects of environmental toxicants on oogenesis

There has been a global decline in fertility rates, with ovulatory disorders emerging as the leading cause, contributing to a global lifetime infertility prevalence of 17.5%. Formation of the primordial follicle pool during early and further development of oocytes after puberty is crucial in determining female fertility and reproductive quality. However, the increasing exposure to environmental toxins (through occupational exposure and ubiquitous chemicals) in daily life is a growing concern; these toxins have been identified as significant risk factors for oogenesis in women. In light of this concern, this review aims to enhance our understanding of female reproductive system diseases and their implications. Specifically, we summarized and categorized the environmental toxins that can affect oogenesis. Here, we provide an overview of oogenesis, highlighting specific stages that may be susceptible to the influence of environmental toxins. Furthermore, we discuss the genetic and molecular mechanisms by which various environmental toxins, including metals, cigarette smoke, and agricultural and industrial toxins, affect female oogenesis. Raising awareness about the potential risks associated with toxin exposure is crucial. However, further research is needed to fully comprehend the mechanisms underlying these effects, including the identification of biomarkers to assess exposure levels and predict reproductive outcomes. By providing a comprehensive overview, this review aims to contribute to a better understanding of the impact of environmental toxins on female oogenesis and guide future research in this field.

Role of NRF2 in Ovarian Cancer

Among gynaecologic malignancies, ovarian cancer is one of the most dangerous, with a high fatality rate and relapse due to the occurrence of chemoresistance. Many researchers demonstrated that oxidative stress is involved in tumour occurrence, growth and development. Nuclear factor erythroid 2-related factor 2 (NRF2) is an important transcription factor, playing an important role in protecting against oxidative damage. Increased levels of Reactive Oxygen Species (ROS) activate NRF2 signalling, inducing the expression of antioxidant enzymes, such as haem oxygenase (HO-1), catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD), that protect cells against oxidative stress. However, NRF2 activation in cancer cells is responsible for the development of chemoresistance, inactivating drug-mediated oxidative stress that normally leads to cancer cells’ death. In this review, we report evidence from the literature describing the effect of NRF2 on ovarian cancer, with a focus on its function in drug resistance, NRF2 natural and synthetic modulators and its protective function in normal ovarian preservation.

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.

Effects of paternal exposure to cigarette smoke on sperm DNA methylation and long-term metabolic syndrome in offspring

BACKGROUND

Although paternal exposure to cigarette smoke may contribute to obesity and metabolic syndrome in offspring, the underlying mechanisms remain uncertain.

METHODS

In the present study, we analyzed the sperm DNA-methylation profiles in tobacco-smoking normozoospermic (SN) men, non-tobacco-smoking normozoospermic (N) men, and non-smoking oligoasthenozoospermic (OA) men. Using a mouse model, we also analyzed global methylation and differentially methylated regions (DMRs) of the DLK1 gene in paternal spermatozoa and the livers of progeny. In addition, we quantified DLK1 expression, executed an intra-peritoneal glucose tolerance test (IPGTT), measured serum metabolites, and analyzed liver lipid accumulation in the F1 offspring.

RESULTS

Global sperm DNA-methylation levels were significantly elevated (p  < 0.05) in the SN group, and the methylation patterns were different among N, SN, and OA groups. Importantly, the methylation level of the DLK1 locus (cg11193865) was significantly elevated in the SN group compared to both N and OA groups (p  < 0.001). In the mouse model, the group exposed to cigarette smoke extract (CSE) exhibited a significantly higher global methylation DNA level in spermatozoa (p  < 0.001) and on the DMR sites of Dlk1 in 10-week-old male offspring (p  < 0.05), with a significant increase in Dlk1 expression in their livers (p  < 0.001). In addition, IPGTT and LDL levels were significantly altered (p  < 0.001), with elevated liver fat accumulation (p  < 0.05) in F1 offspring.

CONCLUSION

Paternal exposure to cigarette smoke led to increased global methylation of sperm DNA and alterations to the DMR of the DLK1 gene in the F1 generation, which may be inherited parentally and may perturb long-term metabolic function.

Maternal cigarette smoking before or during pregnancy increases the risk of birth congenital anomalies: a population-based retrospective cohort study of 12 million mother-infant pairs

BACKGROUND

The associations of maternal cigarette smoking with congenital anomalies in offspring have been inconsistent. This study aimed to clarify the associations of the timing and intensity of maternal cigarette smoking with 12 subtypes of birth congenital anomalies based on a nationwide large birth cohort in the USA.

METHODS

We used nationwide birth certificate data from the US National Vital Statistics System during 2016-2019. Women reported the average daily number of cigarettes they consumed 3 months before pregnancy and in each subsequent trimester during pregnancy. Twelve subtypes of congenital anomalies were identified in medical records. Poisson regression analysis was used to estimate the risk ratios (RRs) with 95% confidence intervals (CIs) for 12 subtypes of congenital anomalies associated with the timing (i.e., before pregnancy, and during three different trimesters of pregnancy) and intensity (i.e., number of cigarettes consumed per day) of maternal cigarette smoking.

RESULTS

Among the 12,144,972 women included, 9.3% smoked before pregnancy and 7.0%, 6.0%, and 5.7% in the first, second, and third trimester, respectively. Maternal smoking before or during pregnancy significantly increased the risk of six subtypes of birth congenital anomalies (i.e., congenital diaphragmatic hernia, gastroschisis, limb reduction defect, cleft lip with or without cleft palate, cleft palate alone, and hypospadias), even as low as 1-5 cigarettes per day. The adjusted RRs (95% CIs) for overall birth congenital anomalies (defined as having any one of the congenital malformations above significantly associated with maternal cigarette smoking) among women who smoked 1-5, 6-10, and ≥ 11 cigarettes per day before pregnancy were 1.31 (1.22-1.41), 1.25 (1.17-1.33), and 1.35 (1.28-1.43), respectively. Corresponding values were 1.23 (1.14-1.33), 1.33 (1.24-1.42), 1.33 (1.23-1.43), respectively, for women who smoked cigarettes in the first trimester; 1.32 (1.21-1.44), 1.36 (1.26-1.47), and 1.38 (1.23-1.54), respectively, for women who smoked cigarettes in the second trimester; and 1.33 (1.22-1.44), 1.35 (1.24-1.47), and 1.35 (1.19-1.52), respectively, for women who smoked cigarettes in the third trimester. Compared with women who kept smoking before and throughout pregnancy, women who never smoked had significantly lower risk of congenital anomalies (RR 0.77, 95% CI 0.73-0.81), but women who smoked before pregnancy and quitted during each trimester of pregnancy had no reduced risk (all P > 0.05).

CONCLUSIONS

Maternal smoking before or during pregnancy increased the risk of several birth congenital anomalies, even as low as 1-5 cigarettes per day. Maternal smokers who stopped smoking in the subsequent trimesters of pregnancy were still at an increased risk of birth congenital anomalies. Our findings highlighted that smoking cessation interventions should be implemented before pregnancy.

Distinct sex-dependent effects of maternal preconception nicotine and enrichment on the early development of rat offspring brain and behavior

Developmental nicotine exposure is harmful to offspring. Whereas much is known about the consequences of prenatal nicotine exposure, relatively little is understood about how maternal preconception nicotine impacts the next generation. Positive experiences, such as environmental enrichment/complexity, have considerable potential to improve developmental outcomes and even treat and prevent drug addiction. Therefore, the current study sought to identify how maternal exposure to moderate levels of nicotine prior to conception impacts offspring development, and if the presumably negative consequence of nicotine could be reversed by concurrent exposure to an enriched environment. We treated female Long Evans rats with nicotine in their drinking water (15 mg nicotine salt/L) for seven weeks while residing in either standard or enriched conditions. Both experiences occurred exclusively prior to mating. Nicotine exposure reduced dam fertility by ~20% (p = .06). Females reared their own litters, and offspring were tested in two assessments of early development: negative geotaxis and open field. Offspring were euthanized at weaning (P21), and their brains were processed with Golgi-Cox solution to allow quantification of dendritic spine density. Results indicate that neither maternal nicotine or enrichment had an impact on maternal care, but male offspring were impaired at negative geotaxis due to maternal nicotine, female offspring showed altered open field exploration due to maternal enrichment, and offspring of both sexes had increased spine density in OFC due to maternal enrichment. Therefore, this experiment provides novel insights into the unique, sex-dependent consequences of maternal preconception nicotine and enrichment on the early development of rat behavior and brain.

Impact of Cigarette Smoking on the Expression of Oxidative Stress-Related Genes in Cumulus Cells Retrieved from Healthy Women Undergoing IVF

The female reproductive system represents a sensitive target of the harmful effects of cigarette smoke, with folliculogenesis as one of the ovarian processes most affected by this exposure. The aim of this study was to analyze the impact of tobacco smoking on expression of oxidative stress-related genes in cumulus cells (CCs) from smoking and non-smoking women undergoing IVF techniques. Real time PCR technology was used to analyze the gene expression profile of 88 oxidative stress genes enclosed in a 96-well plate array. Statistical significance was assessed by one-way ANOVA. The biological functions and networks/pathways of modulated genes were evidenced by ingenuity pathway analysis software. Promoter methylation analysis was performed by pyrosequencing. Our results showed a down-regulation of 24 genes and an up-regulation of 2 genes (IL6 and SOD2, respectively) involved in defense against oxidative damage, cell cycle regulation, as well as inflammation in CCs from smoking women. IL-6 lower promoter methylation was found in CCs of the smokers group. In conclusion, the disclosed overall downregulation suggests an oxidant-antioxidant imbalance in CCs triggered by cigarette smoking exposure. This evidence adds a piece to the puzzle of the molecular basis of female reproduction and could help underlay the importance of antioxidant treatments for smoking women undergoing IVF protocols.

Female Germ Cell Development, Functioning and Associated Adversities under Unfavorable Circumstances

In the present era, infertility is one of the major issues which restricts many couples to have their own children. Infertility is the inability to achieve a clinical pregnancy after regular unprotected sexual intercourse for the period of one year or more. Various factors including defective male or female germ cell development, unhealthy and improper lifestyles, diseases like cancer and associated chemo-or-radiation therapies, congenital disorders, etc., may be responsible for infertility. Therefore, it is highly important to understand the basic concepts of germ cell development including primordial germ cell (PGC) formation, specification, migration, entry to genital ridges and their molecular mechanisms, activated pathways, paracrine and autocrine signaling, along with possible alteration which can hamper germ cell development and can cause adversities like cancer progression and infertility. Knowing all these aspects in a proper way can be very much helpful in improving our understanding about gametogenesis and finding possible ways to cure related disorders. Here in this review, various aspects of gametogenesis especially female gametes and relevant factors causing functional impairment have been thoroughly discussed.

The Role of Oxidative Stress and Natural Antioxidants in Ovarian Aging

The ovarian system comprises vital organs in females and is of great significance for the maintenance of reproductive potential and endocrine stability. Although complex pathogenesis undoubtedly contributes to ovarian aging, increasing attention is being paid to the extensive influence of oxidative stress. However, the role of oxidative stress in ovarian aging is yet to be fully elucidated. Exploring oxidative stress-related processes might be a promising strategy against ovarian aging. In this review, compelling evidence is shown that oxidative stress plays a role in the etiology of ovarian aging and promotes the development of other ovarian aging-related etiologies, including telomere shortening, mitochondrial dysfunction, apoptosis, and inflammation. In addition, some natural antioxidants such as quercetin, resveratrol, and curcumin have a protective role in the ovaries through multiple mechanisms. These findings raise the prospect of oxidative stress modulator-natural antioxidants as therapeutic interventions for delaying ovarian aging.

Gamete quality in a multistressor environment

Over the past few decades, accumulated evidence confirms that the global environment conditions are changing rapidly. Urban industrialization, agriculture and globalization have generated water, air and soil pollution, giving rise to an environment with a growing number of stress factors, which has a serious impact on the fitness, reproduction and survival of living organisms. The issue raises considerable concern on biodiversity conservation, which is now at risk: it is estimated that a number of species will be extinct in the near future. Sexual reproduction is the process that allows the formation of a new individual and is underpinned by gamete quality defined as the ability of spermatozoa and oocytes to interact during fertilization leading to the creation and development of a normal embryo. This review aimed to provide the current state of knowledge regarding the impact of a broad spectrum of environmental stressors on diverse parameters used to estimate and evaluate gamete quality in humans and in canonical animal models used for experimental research. Effects of metals, biocides, herbicides, nanoparticles, plastics, temperature rise, ocean acidification, air pollution and lifestyle on the physiological parameters that underlie gamete fertilization competence are described supporting the concept that environmental stressors represent a serious hazard to gamete quality with reproductive disorders and living organism failure. Although clear evidence is still limited, gamete capacity to maintain and/or recover physiological conditions is recently demonstrated providing further clues about the plasticity of organisms and their tolerance to the pressures of pollution that may facilitate the reproduction and the persistence of species within the scenario of global change. Changes in the global environment must be urgently placed at the forefront of public attention, with a massive effort invested in further studies aimed towards implementing current knowledge and identifying new methodologies and markers to predict impairment of gamete quality.

Does cigarette smoking really have a clinical effect on folliculogenesis and oocyte maturation?

Infertility is the most common issue in the field of reproductive medicine. Many factors affect fertility status, including life-style choices such as cigarette smoking or alcohol use. The aim of this study was to investigate the effects of cigarette smoking on oocyte quality as well the quantity in young fertile women. In total, 56 young fertile women who were undergoing oocyte donation programmes were included in this study. The effects of cigarette smoking on antral follicle count, number of follicles and oocytes retrieved and morphology were assessed by an expert embryologist. The results of this study showed that cigarette smoking did not have a significant effect on the follicle count or the number of oocytes retrieved from young and fertile women. However, a significant difference was observed in the morphological assessment. In conclusion, although cigarette smoking does not seem to affect oocyte development, it had an effect on cytoplasmic anomalies and therefore may lower pregnancy chance. Therefore, it is crucial to give proper counselling to patients who are trying to become pregnant both naturally and by in vitro fertilization.

Trichostatin A alleviated ovarian tissue damage caused by cigarette smoke exposure

Cigarette smoke (CS) has a negative impact on women's health and fertility. Studies have shown that histone deacetylases 1 and 2 (HDAC1/2) were involved in oocyte development. However, the roles of HDAC1/2 in ovarian toxicity caused by CS exposure and the therapeutic potential of trichostatin A (TSA, a HDAC inhibitor) for ovarian tissue damage have not been investigated. In this study, Female C57BL/6 mice were exposed to CS from six cigarettes mixed with indoor air for 120 min (one cigarette for 20 min) using a whole-body mainstream smoke exposure system twice daily for 30 days. TSA (0.6 mg/kg body weight) was injected intraperitoneally into mice in the Control + TSA group and CS + TSA group every two days for 30 days. We found that exposure to CS resulted in ovarian tissue damage and HDAC1/2 over-expression. TSA alleviated the structural changes of ovarian tissue induced by smoking and prevented the activation of HDAC1/2. Exposure to CS caused autophagy inhibition and pyroptosis activation. TSA treatment restored the expression of autophagy-associated proteins and decreased the levels of pyroptosis-related proteins induced by CS exposure. The TSA effect may be mediated by inhibition of HDAC1/2 involved in autophagy and pyroptosis process.

Smoke, alcohol and drug addiction and female fertility

BACKGROUND

Considerable interest has been gathered on the relevant impact of preventable factors, including incorrect lifestyle and unhealthy habits, on female fertility. Smoking, alcohol and addictive drugs consumption represent a major concern, given the broad range of diseases which might be favored or exacerbated by these dependable attitudes. Despite the well-characterized effects of prenatal exposure on pregnancy outcomes and fetus health, a substantial proportion of women of reproductive age is still concerned with these habits. At present, the impact of smoke, alcohol and addictive drugs on women fertility, and, particularly, the specific targets and underlying mechanisms, are still poorly understood or debated, mainly due to the scarcity of well-designed studies, and to numerous biases.

OBJECTIVE

The current review will provide a comprehensive overview of clinical and experimental studies in humans and animals addressing the impact of smoke, alcohol and addictive drugs on female fertility, by also embracing effects on ovary, oviduct, and uterus, with particular reference to primary endpoints such as ovarian reserve, steroidogenesis, ovulation and menstrual cycle, oviduct function and uterus receptivity and implantation. A brief focus on polycystic ovary syndrome and endometriosis will be also included.

METHODS

A Pubmed literature search was performed with selected keywords; articles were individually retrieved by each author. No limitation was set for publication date. Articles in languages other than English were excluded. Additional articles were retrieved from references list of selected manuscripts.

RESULTS AND CONCLUSIONS

Currently, the most consistent evidences of a detrimental effect of smoke, alcohol and addictive drugs on specific domains of the female reproductive function are provided by experimental studies in animals. Overall, clinical studies suggest that smoking is associated to decreased fertility, although causal inference should be further demonstrated. Studies addressing the effect of alcohol consumption on female fertility provide conflicting results, although the majority reported lack of a correlation. Extremely scarce studies investigated the effects of addictive drugs on female fertility, and the specific actions of selected drugs have been difficult to address, due to multidrug consumption.

Adolescent diabetes induced by multiple parental exposures to cigarette smoke condensate

Parental exposure to cigarette smoke is closely related to the development of long-term metabolic diseases in the offspring. However, different exposure times at various developmental stages may cause these effects to vary. In this study, mice were exposed to cigarette smoke condensate (CSC) during the developmental time stages of paternal puberty or/and maternal pregnancy. The results showed that either paternal or maternal exposure to CSC could lead to increased low birth weight (LBW) and fetal growth restriction (FGR) of the offspring, but maternal factors were the leading ones. Moreover, maternal exposure during pregnancy could induce lipid metabolism abnormalities in the adulthood offspring. Most importantly, additional paternal CSC exposure further induced diabetes in adolescent offspring who experienced altered weight gain, blood lipids, and glucose metabolism. A preliminary analysis indicated that the offspring with metabolic abnormalities also had significant changes in their intestinal microbiota. In conclusion, this study showed that parental CSC exposure has an impact on the metabolic properties of the offspring, and multiple parental exposures to adverse factors may significantly increase the risk of long-term metabolic abnormalities.

Exposure to cigarette smoke via respiratory system may induce abnormal alterations of reproductive organs in female diabetic rats

Cigarette smoke (CS) has harmful effects on human fertility, reproduction, and development as well as on patients suffering from metabolic diseases such as diabetes than on healthy individuals. This study was conducted to investigate the relationship between CS exposure and histological alterations of reproductive organs in female diabetic rats. We evaluated the histology of uteruses and ovaries obtained from female rats exposed to smoke from standard cigarettes for 4 weeks (28 hours a week). After CS exposure, tissue slides were made from uterine and ovarian samples and examined after hematoxylin and eosin staining. Immunohistochemistry was used for detection of matrix metallopeptidase 9 (MMP9), C-X-C chemokine receptor type 4 (CXCR4), and estrogen receptor (ER)α in the uterus and ovary. MMP9 is an inflammatory biomarker that increases during progression to endometriosis. As a chemokine receptor, CXCR4 is involved in development of the inner wall of the uterus and cell adhesion. In the uterus, the occurrence of MMP9, CXCR4, and ERα and the number of endometrial glands were increased by CS exposure, while in the ovary, occurrence of MMP9, CXCR4, ERα, proliferating cell nuclear antigen and the number of corpus lutea or cyst follicles were increased by CS exposure. Collectively, this study indicates that CS induced abnormal development of the uterus and ovary under induced diabetes, leading to adverse effects on normal function of reproductive organs in female rats. HIGHLIGHTS: Cigarette smoke (CS) exposure adversely affected reproductive organs of diabetic female rats. In the uterus, expression of matrix metallopeptidase 9 (MMP9), C-X-C chemokine receptor type 4 (CXCR4), estrogen receptor (ER)α, and the number of endometrial glands were increased by CS exposure, In the ovary, the expression of MMP9, CXCR4, ERα, and proliferating cell nuclear antigen and the number of corpus lutea or cyst follicles were increased by CS exposure. Exposure to CS via the respiratory system exerted a harmful impact on the uterus and ovary in female rats with diabetes.

Testosterone and testicular changes in F1 offspring of Wistar rats maternally exposed to nicotine during gestation

OBJECTIVES

This study aimed to determine the effect of intrauterine exposure to nicotine in the first fourteen days of gestation on the testicular function of male Wistar rats.

METHODS

Pups of both control and nicotine-treated groups were selected and sacrificed on day 60 after birth. Birth weight, weight of reproductive organs, hormonal profile, and histopathology were determined in the first filial (F1) generation.

RESULTS

Significant decreases in birth weight and litter size were found in the pups treated with nicotine when compared with the animals in the control group. Significant decreases were also observed in the testicular weight of nicotine-treated rats, but not in epididymal weight, when compared to controls. Testosterone levels were significantly decreased, atrophy was observed in the genital epithelial cells, and distortions were noted in the testes of nicotine-treated F1 males.

CONCLUSION

These results suggest that nicotine exposure during pregnancy may cause endocrine disruption, and thus produce deleterious effects on offspring reproductive function.

Cigarette smoking impairs clinical outcomes of assisted reproductive technologies: A meta-analysis of the literature

There is convincing evidence that cigarette smoking can impair female reproductive potential. This meta-analysis updates the knowledge regarding the effects of cigarette smoking on clinical outcomes of assisted reproductive technologies (ART). Twenty-six studies were included in this meta-analysis. Results were expressed as odds ratios (OR) with 95% confidence intervals (CI) and statistical heterogeneity between the studies was evaluated with Higgins (I²), Breslow (τ²), Birge's ratio (H²) indices and Chi-square test (χ²). A P-value < 0.05 was considered statistically significant. The analysis showed a significant decrease in live birth rate per cycle for smoking patients (OR 0.59, 95% CI 0.44-0.79; P = 0.0005), a significant lower clinical pregnancy rate per cycle for smoking women (OR 0.53, 95% CI 0.41-0.68; P < 0.0001), and a significant increase in terms of spontaneous miscarriage rate (OR 2.22, 95% CI 1.10-4.48; P = 0.025) for smokers. These findings demonstrate clear negative effects of cigarette smoking on the outcome of ART programs.

Multigenerational effects of maternal cigarette smoke exposure during pregnancy on sperm counts of F1 and F2 male offspring

Animal models and human studies showed that in utero cigarette smoke exposure decreases sperm counts of offspring. This study used a mouse model to investigate the effects of maternal exposure to cigarette smoke on reproductive systems in F1 and F2 male offspring. Female ICR mice were exposed either to clean air or to cigarette smoke during pregnancy at the post-implantation stage. Epididymal sperm counts were decreased in a cigarette smoke dose-dependent manner in F1 (by 40-60%) and F2 males (by 23-40%) at postnatal day 56. In F1, the seminiferous epithelium heights were lower in the cigarette smoke-exposed groups than in the control group, and these effects were sustained in F2 males. Results suggest that maternal cigarette smoke exposure during pregnancy can have a multigenerational adverse effect on sperm counts in male offspring, which is mediated through in utero exposure of fetal germ cells to cigarette smoke.

Ovotoxicity of cigarette smoke: A systematic review of the literature

This study reviews the scientific literature on the noxious effects of cigarette smoke on the ovarian follicle, and the cumulative data on the impact of smoking on in vitro fertilization (IVF) cycle outcome. There is a close association between tobacco smoke and accelerated follicle loss, abnormal follicle growth and impairment of oocyte morphology and maturation. There is an increasing amount of evidence indicating that smoke can directly derange folliculogenesis. Increased cellular apoptosis or autophagy, DNA damage and abnormal crosstalk between oocyte and granulosa cells have been implicated in the demise of ovarian follicles. It becomes increasingly clear that maternal smoking can exert multigenerational effects on the ovarian function of the progeny. Growing evidence suggests that cigarette smoke is associated with decreased results after IVF. Further research is needed to better define the molecular mechanisms behind smoking-induced ovarian disruption.

Cigarette smoke is associated with altered expression of antioxidant enzymes in granulosa cells from women undergoing in vitro fertilization

This study was undertaken to evaluate whether cigarette smoke is associated with changes in the expression of antioxidant enzymes in granulosa cells of women undergoing IVF treatments. For this aim, the expression of three antioxidant enzymes (SOD1, SOD2 and catalase) in non-smokers (n = 20) and smokers (n = 20) was analyzed. There was a statistically significant overexpression of SOD2 and catalase mRNA levels in smokers in comparison with non-smokers. Cigarette smoking was associated with a lower fertilization rate, implantation rate and pregnancy rate in comparison with non-smokers. There was no effect on retrieved oocytes number, metaphase II oocytes number, quality of embryos transferred and live birth rate. These findings suggest that cigarette smoke initiates oxidative stress in granulosa cells.

Discrete survival model analysis of a couple's smoking pattern and outcomes of assisted reproduction

Background

Cigarette smoking has been associated with worse infertility treatment outcomes, yet some studies have found null or inconsistent results.

Methods

We followed 225 couples who underwent 354 fresh non-donor assisted reproductive technology (ART) cycles between 2006 and 2014. Smoking history was self-reported at study entry. We evaluated the associations between smoking patterns and ART success using multivariable discrete time Cox proportional hazards models with six time periods: cycle initiation to egg retrieval, retrieval to fertilization, fertilization to embryo transfer (ET), ET to implantation, implantation to clinical pregnancy, and clinical pregnancy to live birth to estimate hazard ratios (HR) and 95% CIs. Time-dependent interactions between smoking intensity and ART time period were used to identify vulnerable periods.

Results

Overall, 26% of women and 32% of men reported ever smoking. The HR of failing in the ART cycle without attaining live birth for male and female ever smokers was elevated, but non-significant, compared to never smokers regardless of intensity (HR = 1.02 and 1.30, respectively). Female ever smokers were more likely to fail prior to oocyte retrieval (HR: 3.37; 95% CI: 1.00, 12.73). Every one cigarette/day increase in smoking intensity for females was associated with a HR of 1.02 of failing ART (95% CI: 0.97, 1.08), regardless of duration or current smoking status. Women with higher smoking intensities were most likely to fail a cycle prior to oocyte retrieval (HR: 1.07; 95% CI: 1.00, 1.16). Among past smokers, every additional year since a man had quit smoking reduced the risk of failing ART by 4% (HR: 0.96; 95% CI: 0.91, 1.00) particularly between clinical pregnancy and live birth (HR: 0.86; 95% CI: 0.76, 0.96).

Conclusions

Female smoking intensity, regardless of current smoking status, is positively associated with the risk of failing ART cycles between initiation and oocyte retrieval. In men who ever smoked, smoking cessation may reduce the probability of failing ART, particularly between clinical pregnancy and live birth.

Trial registration

NCT00011713. Registered: 27 February 2001.

Electronic supplementary material

The online version of this article (doi:10.1186/s40738-017-0032-2) contains supplementary material, which is available to authorized users.