Phosphoramide mustard induces autophagy markers and mTOR inhibition prevents follicle loss due to phosphoramide mustard exposure

Phosphoramide mustard (PM) is an ovotoxic metabolite of cyclophosphamide. Postnatal day 4 Fisher 344 rat ovaries were exposed to vehicle control (1% DMSO) or PM (60μM)±LY294002 or rapamycin for 2 or 4 d. Transmission election microscopy revealed abnormally large golgi apparatus and electron dense mitochondria in PM-exposed ovaries prior to and at the time of follicle depletion. PM exposure increased (P<0.05) mRNA abundance of Bbc3, Cdkn1a, Ctfr, Edn1, Gstp1, Nqo1, Tlr4, Tnfrsfla, Txnrd1 and decreased (P<0.05) Casp1 and Il1b after 4d. PM exposure increased (P<0.1) BECN1 and LAMP, decreased (P<0.1) ABCB1 and did not alter ABCC1 protein. LY294002 did not impact PM-induced ovotoxicity, but decreased ABCC1 and ABCB1 protein. Rapamycin prevented PM-induced follicle loss. These data suggest that the mammalian target of rapamycin, mTOR, may be a gatekeeper of PM-induced follicle loss.

Smoking, alcohol and caffeine in relation to two hormonal indicators of ovarian age during the reproductive years

OBJECTIVE

To examine whether or not cigarette smoking, alcohol and caffeine intake are related to two indicators of ovarian age-anti-Müllerian hormone (AMH) and follicle stimulating hormone (FSH).

STUDY DESIGN

Cross-sectional study of 477 women with a recent index spontaneous abortion (SA) (105 trisomic, 93 non-trisomic) or livebirth (LB) (279) with hormones measured on days 2-4 of an apparently normal menstrual cycle after the index pregnancy.

RESULTS

Current smoking is associated with about a 15% increase in median FSH (β for ln(FSH)=0.14, 95% CI 0.03,0.25). It is not significantly related to AMH (β for ln(AMH)=-0.25, 95% CI -0.56,0.06). Neither alcohol 2-7days per week nor caffeine 122-<553mg per day is independently related to AMH or FSH.

CONCLUSIONS

The observation that current smoking is associated with FSH, but not with AMH, suggests that current smoking either impairs the development of antral follicles or dysregulates the hypothalamic-pituitary-ovarian axis. The absence of an association with AMH argues against mechanisms related to accelerated follicle atresia.

The Mouse Fetal Ovary Has Greater Sensitivity Than the Fetal Testis to Benzo[a]pyrene-Induced Germ Cell Death

The polycyclic aromatic hydrocarbon pollutant benzo[a]pyrene (BaP) is a known developmental gonadotoxicant. However, the mechanism of BaP-induced germ cell death is unclear. We investigated whether exposure to BaP induces apoptotic germ cell death in the mouse fetal ovary or testis. Mouse fetal gonads were dissected at embryonic day 13.5 days postcoitum (dpc) and fixed immediately or cultured for 6, 24, 48, or 72 h with various concentrations of BaP (1-1000 ng/ml). Germ cells numbers, apoptosis, and proliferation were evaluated by immunostaining. Treatment of fetal ovaries with BaP for 72 h concentration-dependently depleted germ cells. Treatment with BaP elevated the expression of BAX protein at 6 h and activated downstream caspases-9 and -3 at 24 h in a concentration-dependent manner in germ cells of fetal ovaries. As a consequence, ovarian germ cell numbers were significantly and concentration-dependently decreased at 48 h. Pretreatment with z-VAD-fmk, a pan-caspase inhibitor, prior to exposure to 1000 ng/ml BaP prevented BaP-mediated ovarian germ cell death; there were no effects of BaP or z-VAD-fmk on germ cell proliferation. No significant effects of BaP exposure on caspase 3 activation or germ cell numbers were observed in fetal testes after 48 h of culture. Our findings show that BaP exposure increases caspase-dependent and BAX-associated germ cell apoptosis in the mouse fetal ovary, leading to germ cell depletion. In contrast, the cultured 13.5 dpc fetal testis is relatively resistant to BaP-induced germ cell death. This study provides a novel insight into molecular mechanisms by which BaP has direct gonadotoxicity in the mouse fetal ovary.

Cigarette smoke exposure triggers the autophagic cascade via activation of the AMPK pathway in mice

We previously demonstrated that cigarette smoke (CS) exposure decreases primordial follicle counts and induces autophagy in ovarian granulosa cells in preference to apoptosis. Therefore, the objective of this study was to investigate molecular targets underlying smoke-induced activation of the reparative autophagy pathway in the ovary. Briefly, ovarian homogenates were prepared from adult female mice exposed to mainstream CS twice daily for 8 wk, using a whole-body exposure system. A gene array revealed that CS exposure induced a greater than 2-fold significant increase in the expression of proautophagic genes Cdkn1b, Map1lc3a, Bad, and Sqstm1/p62. A significant increase in Prkaa2, Pik3c3, and Maplc31b expression, as well as a significant decrease in Akt1 and Mtor expression, was detected by quantitative PCR. The 5'-AMP-activated protein kinase catalytic subunit (AMPK) alpha1 + alpha2 and ATG7 protein expression was significantly increased, whereas AKT1, mTOR, CDKN1B/p27, and CXCR4 proteins were significantly decreased in CS exposed versus control ovaries. Up-regulation of AMPK alpha1 + alpha2, a known initiator of autophagic signaling, and ATG7 further suggests activation of the autophagy cascade. Two prosurvival factors, AKT and mTOR, were decreased in expression, an outcome that favors induction of the autophagy pathway, whereas decreased levels of CDKN1B is suggestive of cell cycle dysregulation. In summary, our data suggest that CS exposure induces ovarian follicle loss through induction of the autophagic cascade via the AMPK pathway together with inhibition of antiautophagic markers AKT and mTOR. We further postulate that toxicant-induced dysregulation of reparative autophagy is a novel pathway central to impaired follicle development and subfertility.

In vitro evaluation of the anti-apoptotic drug Z-VAD-FMK on human ovarian granulosa cell lines for further use in ovarian tissue transplantation

PURPOSE

Because ovarian granulosa cells are essential for oocyte survival, we examined three human granulosa cell lines as models to evaluate the ability of the pan-caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone (Z-VAD-FMK) to prevent primordial follicle loss after ovarian tissue transplantation.

METHODS

To validate the efficacy of Z-VAD-FMK, three human granulosa cell lines (GC1a, HGL5, COV434) were treated for 48 h with etoposide (50 μg/ml) and/or Z-VAD-FMK (50 μM) under normoxic conditions. To mimic the ischemic phase that occurs after ovarian fragment transplantation, cells were cultured without serum under hypoxia (1 % O(2)) and treated with Z-VAD-FMK. The metabolic activity of the cells was evaluated by WST-1 assay. Cell viability was determined by FACS analyses. The expression of apoptosis-related molecules was assessed by RT-qPCR and Western blot analyses.

RESULTS

Our assessment of metabolic activity and FACS analyses in the normoxic experiments indicate that Z-VAD-FMK protects granulosa cells from etoposide-induced cell death. When cells are exposed to hypoxia and serum starvation, their metabolic activity is reduced. However, Z-VAD-FMK does not provide a protective effect. In the hypoxic experiments, the number of viable cells was not modulated, and we did not observe any modifications in the expressions of apoptosis-related molecules (p53, Bax, Bcl-xl, and poly (ADP-ribose) polymerase (PARP)).

CONCLUSION

The death of granulosa cell lines was not induced in our ischemic model. Therefore, a protective effect of Z-VAD-FMK in vitro for further use in ovarian tissue transplantation could not be directly confirmed. It will be of interest to potentially use Z-VAD-FMK in vivo in xenograft models.

Glutamate Cysteine Ligase Modifier Subunit (Gclm) Null Mice Have Increased Ovarian Oxidative Stress and Accelerated Age-Related Ovarian Failure

Glutathione (GSH) is the one of the most abundant intracellular antioxidants. Mice lacking the modifier subunit of glutamate cysteine ligase (Gclm), the rate-limiting enzyme in GSH synthesis, have decreased GSH. Our prior work showed that GSH plays antiapoptotic roles in ovarian follicles. We hypothesized that Gclm(-/-) mice have accelerated ovarian aging due to ovarian oxidative stress. We found significantly decreased ovarian GSH concentrations and oxidized GSH/oxidized glutathione redox potential in Gclm(-/-) vs Gclm(+/+) ovaries. Prepubertal Gclm(-/-) and Gclm(+/+) mice had similar numbers of ovarian follicles, and as expected, the total number of ovarian follicles declined with age in both genotypes. However, the rate of decline in follicles was significantly more rapid in Gclm(-/-) mice, and this was driven by accelerated declines in primordial follicles, which constitute the ovarian reserve. We found significantly increased 4-hydroxynonenal immunostaining (oxidative lipid damage marker) and significantly increased nitrotyrosine immunostaining (oxidative protein damage marker) in prepubertal and adult Gclm(-/-) ovaries compared with controls. The percentage of small ovarian follicles with increased granulosa cell proliferation was significantly higher in prepubertal and 2-month-old Gclm(-/-) vs Gclm(+/+) ovaries, indicating accelerated recruitment of primordial follicles into the growing pool. The percentages of growing follicles with apoptotic granulosa cells were increased in young adult ovaries. Our results demonstrate increased ovarian oxidative stress and oxidative damage in young Gclm(-/-) mice, associated with an accelerated decline in ovarian follicles that appears to be mediated by increased recruitment of follicles into the growing pool, followed by apoptosis at later stages of follicular development.

Prenatal smoking and age at menarche: influence of the prenatal environment on the timing of puberty

STUDY QUESTION

Do prenatal exposure to cigarette smoking and birthweight influence age at menarche (AAM) in a cohort of Australian girls?

SUMMARY ANSWER

We find that prenatal smoke exposure and lower birthweight increase the chance of earlier menarche in accordance with theoretical predictions as do confounding factors of maternal AAM and higher BMI of the girls.

WHAT IS KNOWN ALREADY

Much prior research focuses on the role of the early childhood environment in determining AAM but fewer studies consider the role of the prenatal environment. Those studies that examine the prenatal period find an acceleration of maturation associated with maternal smoking and low birthweight. Life history theory predicts that early life exposure to stressful environments should promote more rapid maturation and that this timing can be established before birth, making the prenatal environment particularly important.

STUDY DESIGN, SIZE, DURATION

Statistical analysis of longitudinal survey data collected from a large cohort (n = 2446) of Australian children using data from birth to 12-13 years of age.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Owing to missing data, 1493 girls were included in the final analysis. Using cox regression, we examine how (i) maternal cigarette smoking during gestation and (ii) birthweight influence girls' AAM. Cox regression was used because not all girls had reached menarche.

MAIN RESULTS AND THE ROLE OF CHANCE

We find that older maternal AAM (hazards ratio (HR): 0.75, confidence interval (CI) (95%): 0.71-0.79) and higher birthweight (HR: 0.86, CI (95%): 0.75-0.97) lower the chance of earlier menarche; while higher girls' BMI at 8-9 years (HR: 1.12, CI (95%): 1.10-1.15), and maternal cigarette smoking on 'most days' during gestation (HR: 1.40, CI (95%): 1.10-1.79 with 'no smoking' as the reference level) increased the chance of earlier menarche. All factors were statistically significant at P = 0.05.

LIMITATIONS, REASONS FOR CAUTION

Not all girls had reached menarche, necessitating the use of cox regression. As with other longitudinal studies, there was study sample attrition and some missing data, particularly in reports of maternal smoking. In addition, as the degree of bias in the missing data is unknown, possible inaccurate reporting of maternal smoking may influence the results of birthweight on AAM.

WIDER IMPLICATIONS OF THE FINDINGS

Because of the association between younger AAM and higher risk of uterine, endometrial and breast cancer development, our finding adds to the need to consider the stress caused by prenatal smoke exposure as an important health risk. In addition, this study needs to be extended, when the same girls are 14-15 years of age, and on a larger dataset from a younger cohort within the same Australian Government project.

STUDY FUNDING/COMPETING INTERESTS

No funding was received for this study and there are no competing interests to declare.

Technical and performance characteristics of anti-Müllerian hormone and antral follicle count as biomarkers of ovarian response

BACKGROUND

Stratified (individualized) medicine has been recognized as a key priority for policy makers and healthcare providers. The main principle of individualized care depends on utilizing patients' characteristics and biomarkers to predict prognosis, tailor intended treatment and predict treatment outcomes. In reproductive medicine a wide variety of biomarkers have been proposed as predictors of ovarian response; of these, anti-Müllerian hormone (AMH) and antral follicle count (AFC) are purported as exhibiting the most favourable analytical and performance characteristics. Previously AFC and AMH have been considered essentially interchangeable; however, recent trial data have questioned this postulation. The aim of this review is to present an analysis of the strengths and weaknesses of these biomarkers as predictors of ovarian response, using both physiological and technical perspectives.

METHODS

We have conducted a systematic search of the most recent (to May 2014) relevant literature and summarized the existing evidence. Articles written in a language other than English without an available English translation were excluded.

RESULTS

Both AMH values and AFC can be influenced by comparable technical, physiological and exogenous factors. AMH displays some variation within and between cycles, consistent with its physiological role in follicle development, and there are growing data on the impact of pharmacological treatments and pathological conditions but cycle-independent measurement is appropriate for clinical purposes. A range of issues with manual AMH assays may be resolving with the development of fully automated assays. Despite described standardization of its measurement technique, AFC is subject to marked inter- and intra-operator variability and the effects of external influences are likely to be comparable. Outwith some highly specialist centres, the intracyclic variation in AFC requires its measurement between Day 2 and 4 of the cycle. Observational studies suggest comparable performance characteristics for AMH and AFC in predicting poor and high ovarian response, but recent RCTs suggest markedly better performance for AMH.

CONCLUSIONS

The performance characteristics of both AMH and AFC for the prediction of ovarian response to exogenous gonadotrophins have been inflated by single site observational cohorts, resulting in the viewpoint that AMH and AFC exhibit equivalent performance characteristics. Large scale multicentre RCTs, with centralized assay performance, have demonstrated that AMH is substantially the more accurate and robust biomarker, probably reflecting difficulties with standardization of AFC determination. While AFC retains some advantages, particularly immediacy and accessibility, international standardization of AMH combined with a stable automated assay is likely to enhance its performance as the biomarker of choice in predicting the ovarian response in assisted conception.

Through the smoke: use of in vivo and in vitro cigarette smoking models to elucidate its effect on female fertility

A finite number of oocytes are established within the mammalian ovary prior to birth to form a precious ovarian reserve. Damage to this limited pool of gametes by environmental factors such as cigarette smoke and its constituents therefore represents a significant risk to a woman's reproductive capacity. Although evidence from human studies to date implicates a detrimental effect of cigarette smoking on female fertility, these retrospective studies are limited and present conflicting results. In an effort to more clearly understand the effect of cigarette smoke, and its chemical constituents, on female fertility, a variety of in vivo and in vitro animal models have been developed. This article represents a systematic review of the literature regarding four of experimental model types: 1) direct exposure of ovarian cells and follicles to smoking constituents' in vitro, 2) direct exposure of whole ovarian tissue with smoking constituents in vitro, 3) whole body exposure of animals to smoking constituents and 4) whole body exposure of animals to cigarette smoke. We summarise key findings and highlight the strengths and weaknesses of each model system, and link these to the molecular mechanisms identified in smoke-induced fertility changes.

Expression of beclin 1 in non-small cell lung cancer: an immunohistochemical study

BACKGROUND

Cigarette smoking causes a variety of adverse human health effects, including lung cancer. The molecular events associated with smoke-induced carcinogenesis are thought to be related in part to autophagy. Beclin 1 is an important autophagy-related protein involved in cell death and cell survival.

AIM

The purpose of this investigation was to determine the beclin 1 protein and its association with cigarette smoke and the mutation of epidermal growth factor receptor (EGFR) in non-small cell lung cancer (NSCLC).

MATERIAL AND METHODOLOGY

Our study included 108 cases of non-small cell lung cancer who were admitted in our hospital. The beclin 1 protein was detected by immunohistochemistry and EGFR mutation by direct sequencing.

RESULTS

Beclin 1 expression could be detected in 15 (13.9%) of 108 specimens. These studies investigated that beclin 1 expression was associated with heavy smoking, the gender and the histological type of NSCLC (P = 0.023, 0.035 and 0.039). No association of beclin 1 with EGFR mutation was found (P > 0.05).

CONCLUSION

The results from these experiments indicate that heavy smoking may induce the beclin 1 protein in NSCLC.

Prevention of chemotherapy-induced ovarian damage: possible roles for hormonal and non-hormonal attenuating agents

BACKGROUND

Current options for female fertility preservation in the face of cytotoxic treatments include embryo, oocyte and ovarian tissue cryopreservation. However these methods are limited by the patient age, status or available timeframe before treatment and they necessitate invasive procedures. Agents which can prevent or attenuate the ovotoxic effects of treatment would provide significant advantages over the existing fertility preservation techniques, and would allow patients to retain their natural fertility without the necessity for costly, invasive and risky procedures. Recent studies have contributed to our understanding of the mechanisms involved in cytotoxicity-induced ovarian follicle loss and highlight a number of agents that may be able to prevent or reduce this loss.

METHODS

This paper reviews the relevant literature (research articles published in English up to December 2013) on the mechanisms of cytotoxic-induced ovarian damage and the implications for fertility preservation. We present a comprehensive discussion of the potential agents that have been shown to preserve the ovarian follicle reserve in the face of cytotoxic treatments, including an analysis of their respective advantages and risks, and mechanisms of action.

RESULTS

Multiple molecular pathways are involved in the cellular response to cytotoxic treatments, and specific cellular reactions depend on variables including the drug class and dose, cell type, and cell stage. A number of agents acting on different elements of these pathways have demonstrated potential for preventing or reducing ovarian follicle loss, although in most cases, the studies are still very preliminary.

CONCLUSIONS

Advances in our understanding of the mechanisms and pathways involved in both cytotoxic ovarian damage and follicle growth and development have opened up new directions for fertility preservation. In order to bring these agents from the lab to the clinic, it will be vital to accurately evaluate the efficacy of each agent and additionally to demonstrate that co-treatment with these agents will not interfere with the anti-cancer activity of the chemotherapy drugs, or produce genetically comprised embryos.

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

Cigarette smoking can harm fertility, but the existing research has targeted primarily on ovarian follicles, embryos or sex hormone. In this study, we tested cigarette smoke extract on ovulation, oocyte morphology and ovarian gene expression associated with inhibition of oxidative stress using C57BL/6 mice. Mice in the experimental group were administered a cigarette smoke extract (CSE) solution (2 mg/ml) orally daily, while the blank control group was given dimethylsulfoxide (DMSO). A positive control group (menadione) was used that received an intraperitoneal injection of 15 mg/kg menadione in oil solution daily. We found that the CSE group manifested a reduced diameter of zona pellucida-free oocyte (ZP-free OD) and a morphologically misshapen first polar body (PB). Our results suggest that CSE exposure is associated with a shrink size and poor quality of oocytes. Quitting smoking is a wise choice to ensure good fertility.

Acute 7,12-dimethylbenz[a]anthracene exposure causes differential concentration-dependent follicle depletion and gene expression in neonatal rat ovaries

Chronic exposure to the polycyclic aromatic hydrocarbon 7,12-dimethylbenz[a]anthracene (DMBA), generated during combustion of organic matter including cigarette smoke, depletes all ovarian follicle types in the mouse and rat, and in vitro models mimic this effect. To investigate the mechanisms involved in follicular depletion during acute DMBA exposure, two concentrations of DMBA at which follicle depletion has (75 nM) and has not (12.5 nM) been observed were investigated. Postnatal day four F344 rat ovaries were maintained in culture for four days before a single exposure to vehicle control (1% DMSO; CT) or DMBA (12 nM; low-concentration or 75 nM; high-concentration). After four or eight additional days of culture, DMBA-induced follicle depletion was evaluated via follicle enumeration. Relative to control, DMBA did not affect follicle numbers after 4 days of exposure, but induced large primary follicle loss at both concentrations after 8 days; while, the low-concentration DMBA also caused secondary follicle depletion. Neither concentration affected primordial or small primary follicle number. RNA was isolated and quantitative RT-PCR performed prior to follicle loss to measure mRNA levels of genes involved in xenobiotic metabolism (Cyp2e1, Gstmu, Gstpi, Ephx1), autophagy (Atg7, Becn1), oxidative stress response (Sod1, Sod2) and the phosphatidylinositol 3-kinase (PI3K) pathway (Kitlg, cKit, Akt1) 1, 2 and 4 days after exposure. With the exception of Atg7 and cKit, DMBA increased (P < 0.05) expression of all genes investigated. Also, BECN1 and pAKT(Thr308) protein levels were increased while cKIT was decreased by DMBA exposure. Taken together, these results suggest an increase in DMBA bioactivation, add to the mechanistic understanding of DMBA-induced ovotoxicity and raise concern regarding female low concentration DMBA exposures.

The cigarette smoke constituent benzo[a]pyrene disrupts metabolic enzyme, and apoptosis pathway member gene expression in ovarian follicles

Benzo[a]pyrene (B[a]P) is a prototypical polycyclic aromatic hydrocarbon (PAH) present in cigarette smoke. We previously showed that B[a]P adversely affects follicular development and survival. The objective of this study was to identify the key molecular pathways underlying B[a]P-induced abnormal follicular development. Isolated follicles (100-130 μm) from ovaries of F1 hybrid (C57BL/6j×CBA/Ca) mice were cultured for 8 (preantral/antral follicles) and 12 (preovulatory follicles) days in increasing concentrations of B[a]P (0 ng/mL [control] to 45 ng/mL). Expression of aryl hydrocarbon receptor (AhR), aryl hydroxylase steroidogenic enzyme, cell-cycle, and apoptotic genes were quantified. B[a]P exposure significantly (P<0.05) increased mRNA expression of Cyp1a1 in preantral/antral follicles and Cyp1b1, Bax and Hsp90ab1 in preovulatory follicles. No significant effect on mRNA expression of StAR, Cyp11a1, aromatase, Cdk4, Cdk2, Ccnd2, cIAP2, and survivin was observed. In conclusion, this study suggests that B[a]P exposure significantly affects the phase I enzymes and cell death genes during preantral/antral and preovulatory growth, and thus highlight the AhR signaling and apoptotis pathways in delayed follicle growth and decreased viability.

Scrambled and fried: cigarette smoke exposure causes antral follicle destruction and oocyte dysfunction through oxidative stress

Cigarette smoke is a reproductive hazard associated with pre-mature reproductive senescence and reduced clinical pregnancy rates in female smokers. Despite an increased awareness of the adverse effects of cigarette smoke exposure on systemic health, many women remain unaware of the adverse effects of cigarette smoke on female fertility. This issue is compounded by our limited understanding of the molecular mechanisms behind cigarette smoke induced infertility. In this study we used a direct nasal exposure mouse model of cigarette smoke-induced chronic obstructive pulmonary disease to characterise mechanisms of cigarette-smoke induced ovotoxicity. Cigarette smoke exposure caused increased levels of primordial follicle depletion, antral follicle oocyte apoptosis and oxidative stress in exposed ovaries, resulting in fewer follicles available for ovulation. Evidence of oxidative stress also persisted in ovulated oocytes which escaped destruction, with increased levels of mitochondrial ROS and lipid peroxidation resulting in reduced fertilisation potential. Microarray analysis of ovarian tissue correlated these insults with a complex mechanism of ovotoxicity involving genes associated with detoxification, inflammation, follicular activation, immune cell mediated apoptosis and membrane organisation. In particular, the phase I detoxifying enzyme cyp2e1 was found to be significantly up-regulated in developing oocytes; an enzyme known to cause molecular bioactivation resulting in oxidative stress. Our results provide a preliminary model of cigarette smoke induced sub-fertility through cyp2e1 bioactivation and oxidative stress, resulting in developing follicle depletion and oocyte dysfunction.

Cigarette smoke impairs granulosa cell proliferation and oocyte growth after exposure cessation in young Swiss mice: an experimental study

Background

Cigarette smoke is associated with decreased female fertility, causing damage to ovarian function and disturbing follicle development. However, the effects of cigarette toxicants on ovarian function depend on duration and intensity of exposure. The aim of this study was to assess the effects of brief, intense exposure to tobacco smoke on granulosa cell number, oocyte growth, and follicle size during puberty in female Swiss mice.

Methods

Ten female Swiss mice aged 35 days were exposed to tobacco smoke from 3R4F reference research cigarettes. They were exposed to an automatic smoking machine 8 h/day, 7 days/week for 15 days. Ten age-matched controls were kept in a different room and exposed to ambient air. At the end of 15 days, five mice in each group were euthanized and the ovaries were analyzed for follicular morphometry and granulosa cell count. The remaining animals were kept for an additional 30 days for further analysis as an ex-smoker group and control group. Comparison between the two groups was evaluated by the Student’s t-test or a two-way ANOVA followed by Bonferroni post-test was applied for multiple comparisons.

Results

We found that cigarette smoke impaired antral follicular growth even after exposure cessation (p < 0.001). Both smoking and ex-smoking groups exhibited similar follicle diameter. However, at the same follicular stage, the number of granulosa cells was smaller in the ex-smoking group compared to smoking animals (p < 0.001). This was associated with increased oocyte diameter in ex-smoking animals compared to smoking animals (p < 0.01).

Conclusions

The negative effects of cigarette smoking seem to last even after exposure has been interrupted. Moreover, brief exposure during puberty may induce silent oocyte disruption, which could in turn lead to decreased fecundity rates.