Simultaneous effect of lead and cadmium on granulosa cells: a cellular model for ovarian toxicity

Mechanisms of female reproductive toxicity in pigs induced by exposure to environmental pollutants

Environmental pollutants, including endocrine disruptors, heavy metals, nanomaterials, and pesticides, have been detected in various ecosystems and are of growing global concern. The potential for toxicity to non-target organisms has consistently been raised and is being studied using various animal models. In this review, we focus on pesticides frequently detected in the environment and investigate their potential exposure to livestock. Owing to the reproductive similarities between humans and pigs, various in vitro porcine models, such as porcine oocytes, trophectoderm cells, and luminal epithelial cells, are used to verify reproductive toxicity. These cell lines are being used to study the toxic mechanisms induced by various environmental toxicants, including organophosphate insecticides, pyrethroid insecticides, dinitroaniline herbicides, and diphenyl ether herbicides, which persist in the environment and threaten livestock health. Collectively, these results indicate that these pesticides can induce female reproductive toxicity in pigs and suggest the possibility of adverse effects on other livestock species. These results also indicate possible reproductive toxicity in humans, which requires further investigation.

Cadmium as an ovarian toxicant: A review

Cadmium (Cd) is a ubiquitous heavy metal toxicant with no biological function in the human body. Considerably, because of its long biological half-life and very low excretion rate, Cd is inclined to accumulate and cause deleterious effects on various body organs (e.g., liver, kidney, and ovary) in humans and animals. Ovaries are the most vulnerable targets of Cd toxicity. Cd has been shown to induce oxidative stress, follicular atresia, hormonal imbalance, and impairment of oocyte growth and development. Moreover, Cd toxicity has been associated with increasing incidences of menstrual disorders, pregnancy loss, preterm births, delayed puberty, and female infertility. Therefore, it is crucial to understand how Cd poisoning impacts specific ovarian processes for the development of preventive interventions to enhance female fertility. The current review attempts to collate the recent findings on Cd-induced oxidative stress, follicular apoptosis, steroid synthesis inhibition, and teratogenic toxicity, along with their possible mechanisms in the ovarian tissue of different animal species. Additionally, the review also summarizes the studies related to the use of many antioxidants, medicinal herbs, and other compounds as remedial approaches for managing Cd-induced ovarian toxicity.

Toxic Effects of Cadmium on the Female Reproductive Organs a Review

Cadmium (Cd) is a common environmental pollutant present in soil and associated with many modern industrial processes. Cadmium may adversely influence the health of experimental animals and humans and exert significant effects on the reproductive tract morphology and physiology. During embryonic development, cadmium suppresses the normal growth and development of the ovaries, and in adults it disrupts the morphology and function of the ovaries and uterus. The exposure to cadmium has adverse effects on the oocyte meiotic maturation affecting the structure of ovarian tissue. The distribution of follicles and corpus luteum in the ovarian tissues has been shown to be disrupted, affecting the normal growth and development of the follicles. In the ovarian cortex, the number of follicles at different stages of maturation decreased, and the number of atretic follicles increased. In the medulla, oedema and ovarian haemorrhage and necrosis appears at higher doses. Granulosa cells exposed to cadmium exhibited morphological alterations. Oocyte development was inhibited and the amount of oocyte apoptosis was higher. Cadmium exposure also caused changes in the structure of the ovarian blood vessels with reduction in the vascular area. Cadmium effects included increased uterine weight, hyperplasia and hypertrophy of the endometrial lining. Exposure to cadmium had specific effects on gonadal steroidogenesis by suppressing steroid biosynthesis of the ovarian granulosa cells and luteal cells. Progesterone, follicle stimulating hormone, and luteinizing hormone decreased significantly after CdCl2 administration. Cadmium can suppress the female’s ovulation process and cause temporary infertility.

The environment and female reproduction: Potential mechanism of cadmium poisoning to the growth and development of ovarian follicle

Cadmium (Cd) is ubiquitous in our environment and can easily bioaccumulate into the organism after passage through the respiratory and digestive tracts. Long-term exposure to Cd can result in the significant bioaccumulation in organism because of its long biological high-life (10-30 years), which exerts irreversible damages on the health of animals and humans. Although there are increased evidence of impeding the normal function of female reproduction resulted from Cd exposure, the mechanism of the negative action of Cd on the growth and development of ovarian follicle remains enigmatic. Thus, the purpose of the presented study is to summarize available literature which describing Cd-related toxicity involved in the adverse effects on the growth and development of the ovarian follicle. In conclusion, it is suggested that Cd causes damage to the folliculogenesis of mammalians, which results in the decline in the number and quality of ovulated oocytes and the failure in the fertilization. The mechanism behinds that may be linked to the interference to the production of reproductive hormones and the augment of reactive oxygen species (ROS). Furthermore, the enhanced ROS, in turn, impairs various molecules including proteins, lipids and DNA, as well as the balance of the antioxidant defense system, mitochondrial homeostasis, endoplasmic reticulum, autophagy and epigenetic modification. This review is expected to elaborate the toxic mechanism of Cd exposure to the growth and development of ovarian follicles and provide essential remediation strategies to alleviate the damage of Cd to female reproductive health.

Risk Factors Affecting Decreased Libido Among Middle-Aged to Elderly Men; Nocturnal Voiding is an Independent Risk Factor of Decreased Libido

Introduction

Decreased libido in middle-aged and elderly men is often difficult to treat, and identifying the risk factors affecting decreased libido is important for the clinical management of decreased libido. However, limited information is available regarding specific risk factors in this population.

Aim

The present study investigated the risk factors for decreased libido among middle-aged and elderly men.

Methods

Patients who attended our male andropausal outpatient clinic between 2009 and 2015 were enrolled. All patients completed a self-administered questionnaire, which included the Aging Male Symptoms (AMS) scale, International Prostate Symptom Score (IPSS), and Sexual Health Inventory for Men (SHIM). Information on waist size, body mass index, present illness, present use of any medication, and lifestyle habits were collected by each attending physician. Blood biochemical data such as free testosterone, total cholesterol, triglyceride, high density lipoprotein-cholesterol (HDL-Chol), and hemoglobin A1c values were assessed. Libido was assessed based on AMS scale question 17, and a score of 4 or higher was defined as severely decreased libido (severe group).

Main Outcome Measure

The clinical factors associated with severely decreased libido were analyzed based on multiple regression analysis.

Results

A total of 292 subjects were included in the analysis, 111 (38%) of which belonged to the severe group. The mean age of study subjects was 66.2 years, and the mean FT value was 7.1 ± 2.2. Comparisons of each variable among the severe and not severe groups showed significant differences in older age, current cigarette smoking, AMS scale, IPSS, frequency of nocturnal voiding, SHIM score, and HDL-Chol value. Multivariate regression analysis revealed that current cigarette smoking, frequent nocturnal voiding, and a low SHIM score were the independent risk factors for severely decreased libido. Furthermore, the frequency of nocturnal voiding significantly increased with severity of decreased libido.

Conclusion

Current cigarette smoking, frequent nocturnal voiding, and a low SHIM score were the independent risk factors for a severely low libido.

K Shigehara, Y Kato, M Iijima, et al. Risk Factors Affecting Decreased Libido Among Middle-Aged to Elderly Men; Nocturnal Voiding is an Independent Risk Factor of Decreased Libido. Sex Med 2021;9:100426.

Potential mechanism of lead poisoning to the growth and development of ovarian follicle

With the rapid development of economic globalization and industrialization, lead (Pb), one of the most important heavy metals, has been used widely since antiquity for several purposes. In fact, its impact on the health of animals and humans is a significant public health risk all the time. Pb could be accumulated in the body for a long time, causing irreversible damage to the health of animals and humans, including hostile reproductive health. Up to now, although there are some published studies on impeding the normal development of ovarian folliculogenesis of female resulted from Pb exposure, with the damage of structure in uterine tissue, the imbalance of female menstrual status, and the change of hormone levels. The potential mechanism of Pb exposure on female reproduction system, however, remains enigmatic. How to alleviate the damage of Pb toxicity to reproductive function of female has become an urgent problem. Therefore, the aim of the present review is to discuss the information on the growth and development of ovarian follicle of mammalians and the potential toxic mechanism when exposed to Pb. The literatures were collected via various websites and consulting books, reports, etc. In summary, Pb impair folliculogenesis of mammalians, which may be related to the interference to the hypothalamic-pituitary-gonadal (HPG) axis and the production of reactive oxygen species (ROS), in turn impairs various molecules including proteins, lipids and DNA, as well as the disruption of the antioxidant defense system, ionic equilibrium and endoplasmic reticulum homeostasis.

Xylopia aethiopica ethanol seed extract suppresses Cadmium chloride-induced ovary and gonadotropins toxicity in adult female Wistar rats

OBJECTIVE

Xylopia aethiopica is a common plant in West Africa, with wide applications in trado-medical management of several diseases. Thus, our study aimed to analyze the histology and hormonal effects of ethanol extracts of Xylopia aethiopica seeds on cadmium chloride-induced reproductive dysfunction in female Wistar rats.

METHODS

We used twenty-five rats weighing 120-150g for this study. The rats were divided into five groups (n=5). Group 1: received only distilled water orally; Group 2: received 2 mg/kg cadmium chloride orally; Group 3: received 2 mg/kg cadmium chloride plus 50 mg/kg Xylopia aethiopica seeds orally; Group 4: received 2 mg/kg cadmium chloride plus 100 mg/kg Xylopia aethiopica seeds orally, and Group 5: received 100 mg/kg Xylopia aethiopica seeds only, orally. We administered the extracts for 14 days, after which we slaughtered the animals following chloroform anesthesia. We took the blood samples by cardiac puncture for hormonal assay. The ovaries and uterus were harvested for histology. We analyzed the data using ANOVA, and the differences in mean values were considered significant at p<0.05.

RESULTS

The body weight of the rats showed a dose-dependent reduction (p<0.05), compared with the controls. Xylopia aethiopica seeds significantly (p<0.05) reversed the detrimental effects of Cadmium on LH and FSH. The histological analysis of the ovary showed significant improvement upon treatment with Xylopia aethiopica extract in a dose-dependent manner.

CONCLUSIONS

The ameliorative effects of Xylopia aethiopica against cadmium chloride-induced reproductive toxicity in female Wistar rats may be attributed to its antioxidant properties.

Consequences of sodium dodecyl sulfate exposure on the antioxidant status and steroidogenesis in fish gonad

A native Indian catfish (Heteropneustes fossilis) and an Indian major carp (Cirrhinus cirrhosus) were treated with sodium dodecyl sulfate (SDS) to elucidate its consequences on antioxidant status and sex steroid synthesis. Fishes were exposed to 1/10th of LC₅₀ of SDS for 30 days. Different enzymatic and non-enzymatic antioxidants, major sex steroids, steroidogenic enzymes, gonadosomatic index (GSI), and serum cortisol level were measured in both male and female fishes. Levels of enzymatic and non-enzymatic antioxidants altered significantly in both the fish species. Steroid hormones in both male and female fishes decreased significantly in the SDS-treated group. Profiles of steroidogenic enzymes (hydroxysteroid dehydrogenase; 3β-HSD and 17β-HSD) show significant decrease in the SDS treatment group in both carp and catfish than that of the control group irrespective of sexes. GSI also decreases significantly in the SDS-treated group when compared with the control group in spawning phase of carp and catfish irrespective of sexes. Serum cortisol level was increased significantly after SDS exposure. Higher level of cortisol was noted in the spawning phase than that of pre-spawning phase. Current study proves that SDS could interrupt the normal steroidogenesis process in fish, leading to impaired sex hormone production. Detrimental effect of SDS was noted to be more prominent on female steroidogenesis than that of male fish. A species or season-specific variation in steroidogenesis was also observed which indicates that SDS-induced toxicity depends on the sexual status of the specific fish species.

The role of miRNAs in regulating the effect of prenatal cadmium exposure on ovarian granulosa cells in a transgenerational manner in female rats

Cadmium (Cd) is known to affect ovarian granulosa cells (GCs), but no information on the transgenerational effects of Cd on GCs. In this study, pregnant Sprague-Dawley (SD) rats were orally dosed with Cd from gestation day 1 until birth. F1 or F2 female rats were mated with untreated males to produce the F2 or F3 generation. In the F1 generation, apoptotic cell bodies were observed in the Cd-treated group but not in the F2 generation. Moreover, significant changes in B-cell lymphoma 2 (Bcl2) expression were observed in both generations. Additionally, the expression of microRNAs (miRNAs) was significantly changed based on microarray analysis. Specifically, miR-16-5p and miR-181b-5p were upregulated in F1 and F2 rats, while miR-92a-2-5p demonstrated different expression patterns between the two generations. In F3 generation, miR-16-5p and miR-92a-2-5p were down-regulated. Further, another experiment was used to show that miR-16-5p and miR-92a-2-5p regulated the Bcl2-induced apoptotic effect of Cd on GCs by the Human ovarian GC tumor line (COV434 cell line) miRNA-knockdown model Overall, the results indicate that prenatal Cd exposure has epigenetic transgenerational effect on GCs, Moreover, the underlying mechanism may involve interference with miR-16-5p and miR-92a-2-5p-mediated regulation of Bcl2 genes in offspring.

Effects of Cadmium, Lead, and Mercury on the Structure and Function of Reproductive Organs

Reproductive organs are essential not only for the life of an individual but also for the survival and development of the species. The response of reproductive organs to toxic substances differs from that of other target organs, and they may serve as an ideal “barometer” for the deleterious effects of environmental pollution on animal and human health. The incidence of infertility, cancers, and associated maladies has increased in the last fifty years or more, while various anthropogenic activities have released into the environment numerous toxic substances, including cadmium, lead, and mercury. Data from epidemiological studies suggested that environmental exposure to cadmium, lead, and mercury may have produced reproductive and developmental toxicity. The present review focused on experimental studies using rats, mice, avian, and rabbits to demonstrate unambiguously effects of cadmium, lead, or mercury on the structure and function of reproductive organs. In addition, relevant human studies are discussed. The experimental studies reviewed have indicated that the testis and ovary are particularly sensitive to cadmium, lead, and mercury because these organs are distinguished by an intense cellular activity, where vital processes of spermatogenesis, oogenesis, and folliculogenesis occur. In ovaries, manifestation of toxicity induced by cadmium, lead, or mercury included decreased follicular growth, occurrence of follicular atresia, degeneration of the corpus luteum, and alterations in cycle. In testes, toxic effects following exposure to cadmium, lead, or mercury included alterations of seminiferous tubules, testicular stroma, and decrease of spermatozoa count, motility and viability, and aberrant spermatozoa morphology.

MicroRNA-204-5p regulates apoptosis by targeting Bcl2 in rat ovarian granulosa cells exposed to cadmium†

This study aimed to investigate whether cadmium (Cd) cytotoxicity in rat ovarian granulosa cells (OGCs) is mediated through apoptosis or autophagy and to determine the role of microRNAs (miRNAs) in Cd cytotoxicity. To test this hypothesis, rat OGCs were exposed to 0, 10, and 20 μM CdCl2 in vitro. As the Cd concentration increased, OGC apoptosis increased. In addition, Cd promoted apoptosis by decreasing the mRNA and protein expression levels of inhibition of B-cell lymphoma 2 (Bcl2). However, under our experimental conditions, no autophagic changes in rat OGCs were observed, and the mRNA and protein expression levels of the autophagic markers microtubule-associated protein 1 light chain 3 alpha (Map1lc3b) and Beclin1 (Becn1) were not changed. Microarray chip analysis, miRNA screening, and bioinformatics approaches were used to further explore the roles of apoptosis regulation-related miRNAs. In total, 19 miRNAs putatively related to Cd-induced apoptosis in rat OGCs were identified. Notably, miR-204-5p, which may target Bcl2, was identified. Then, rat OGCs were cultured in vitro and used to construct the miR-204-5p-knockdown cell line LV2-short hairpin RNA (shRNA). LV2-shRNA cells were exposed to 20 μM Cd for 12 h, and the mRNA and protein expression levels of Bcl2 were increased. Our findings suggest that Cd is cytotoxic to rat OGCs, and mitochondrial apoptosis rather than autophagy mediates Cd-induced damage to OGCs. Cd also affects apoptosis-related miRNAs, and the underlying apoptotic mechanism may involve the Bcl2 gene.

Urinary cadmium and timing of menarche and pubertal development in girls

BACKGROUND

Cadmium (Cd) is a developmental toxicant that is released into the environment during industrial processes. Previous animal studies suggest that Cd may impact the onset of puberty.

OBJECTIVES

To determine whether Cd exposure, measured as urinary Cd concentration, was associated with ages at menarche and pubertal development.

METHODS

A cohort of 211 girls, ages 10-13 years at baseline, was followed for up to two years. Girls completed an interview and self-assessment of Tanner stages of breast development and pubic hair growth. They were followed monthly until menarche. Urinary Cd concentrations were measured in overnight urine specimens. Multivariable Cox regression was used to evaluate the association between urinary Cd and age at menarche and cumulative logit regression was used to evaluate the associations between urinary Cd and breast development and pubic hair growth.

RESULTS

The baseline geometric mean creatinine-adjusted Cd concentration was 0.22 μg/g creatinine (geometric standard deviation = 1.6) and decreased with increasing age (p-trend = 0.04). Cd levels were higher among Asian than White girls or girls of other/mixed race/ethnicity (p = 0.04). In multivariable analyses, girls with urinary Cd ≥ 0.4 μg/L were less likely to have attained menarche than girls with urinary Cd < 0.2 μg/L (hazard ratio = 0.42; 95% confidence interval, 0.23-0.78). Urinary Cd was negatively associated with pubic hair growth (p-trend = 0.01) but not with breast development (p-trend = 0.72) at baseline.

CONCLUSIONS

These findings suggest that a higher Cd body burden may delay some aspects of pubertal development among girls.

Female Infertility Associated with Blood Lead and Cadmium Levels

Lead and cadmium are known to be potential female reproductive toxins. However, studies on the relationship between these metals and infertility are limited. This study examines the association between self-reported infertility and blood lead and cadmium levels in US women by comparing metal levels in infertile and pregnant women. Data on blood lead, blood cadmium, and infertility from women aged 20–39 years who participated in the 2013–2014 and 2015–2016 National Health and Nutrition Examination Surveys were analyzed (n = 124, ‘pregnant’ n = 42, ‘infertile’ n = 82). Blood lead and cadmium levels were measured using inductively coupled plasma mass spectrometry, and infertility and pregnancy status were assessed using a self-reported questionnaire. Low blood lead and cadmium levels (geometric mean of blood lead = 0.50 µg/dL and blood cadmium = 0.26 µg/L) were positively associated with self-reported infertility after adjusting for confounding effects (odds ratio (OR) for lead per two-fold increase in blood metal levels = 2.60; 95% confidence interval (95% CI), 1.05–6.41 and OR for cadmium per two-fold increase = 1.84; 95% CI, 1.07–3.15). Although our findings require confirmation, they suggest that even low blood cadmium and lead levels may be deleterious to female fecundity.

Enzymatic, Non-enzymatatic Antioxidant Levels and Heat Shock Protein Expression as Indicators of Metal Induced Toxicity and Reproductive Modulation in Female Indian Major Carp Cirrhinus cirrhosus

Effects of zinc (Zn) and lead (Pb) exposure on oxidative biomarkers and heat shock protein (HSP) expression, and their possible relation to ovarian steroidogenesis in fish were investigated. Female Cirrhinus cirrhosus were exposed to 1/10th of LC₅₀ of metals for 30 days, and kept for another 30 days without metal exposure. Metal concentrations, antioxidants, HSPs, 17β-estradiol and steroidogenic enzymes were analysed in brain and ovary after 15 and 30 days of exposure and a 15 and 30 day recovery period. Activities of enzymatic and non-enzymatic antioxidants showed duration dependent variation in both exposure and recovery period. HSP70 and HSP90 expressions increased following metal exposure, with the expression being higher in brain than ovary. 17β-Estradiol, steroidogenic enzymes decreased significantly (p < 0.05) after metal exposure. The present study suggests that metals have differential and tissue specific influence on oxidative status and manipulate ovarian steroidogenesis probably through the modulation of HSPs.

Evidences for involvement of estrogen receptor induced ERK1/2 activation in ovarian cancer cell proliferation by Cadmium Chloride

Cadmium (Cd) as a human carcinogen and one of the most toxic industrial and environmental pollutant mimics the estrogenic effects in cell proliferation. So, it might have a role in the incidence and etiology of hormone-related cancers such as ovarian cancer as the most lethal gynecologic malignancy. This study aimed to evaluate the estrogenic effect and underlying mechanism of Cd in ovarian cancer cell line proliferation. OVCAR3 and SKOV3 cell lines were treated with different concentrations of CdCl₂ (0- 50 μM). Cell proliferation was analyzed using MTT and BrdU assay. To evaluate the estrogenic effect of Cd, the cells were pre-incubated with estrogen receptor (ER) antagonist ICI 182,780. The expression of ER was determined using western blotting method. Real-time RT-PCR method was used to assess c-fos, c-jun and FOXO3a mRNA level. The results showed that Cd has an estrogenic proliferative effect at nM concentration range and ICI 182,780 significantly reversed the CdCl₂-induced cell proliferation. Cd also increased the expression of ERs. Cd exposure induced activation of p-ERK1/2 in these cells. Cd also intensified c-jun, c-fos, and FOXO3a mRNA expression. Taken together, the current work suggests that Cd induces ovarian cancer cell proliferation in an ER-dependent mechanism induced ERK1/2 activation pathway. Understanding of downstream targets by which Cd deregulates cell proliferation can be noteworthy to define its underlying carcinogenesis mechanism.

Cigarette Smoking Is Significantly Linked to Sexual Dissatisfaction in Chinese Heroin-Dependent Patients Receiving Methadone Maintenance Treatment

Background: Cigarette smoking is associated with sexual dysfunction in the general population. Both smoking and sexual dysfunction are common in heroin-dependent patients (HDPs) receiving methadone maintenance treatment (MMT), but their association in MMT HDPs is rarely studied. This study examined the association between smoking and sexual dissatisfaction in Chinese HDPs receiving MMT. Methods: In total, 480 Chinese HDPs, who had sex with their regular or irregular sex partners within one month prior to the study, were included from three MMT clinics in Wuhan, China. Sexual dissatisfaction was assessed with one single question. Socio-demographic and clinical data and smoking characteristics were collected with a standardized questionnaire. Multiple binary logistic regression was used to analyze the association between smoking and sexual dissatisfaction, as well as the associations between levels of smoking and nicotine dependence and sexual dissatisfaction. Results: The prevalence of current smoking was 95.6% in HDPs receiving MMT. Rates of sexual dissatisfaction were higher in current smokers than non-smokers (32.9% vs. 14.3%) with a borderline significant P value of 0.074. After adjusting potential socio-demographic and clinical confounders, current smoking was significantly linked to sexual dissatisfaction (OR = 1.95, P = 0.026), and heavy smoking and severe nicotine dependence were significantly linked to sexual dissatisfaction (OR = 1.80, P = 0.025; OR = 3.27, P < 0.001). Conclusion: Smoking is significantly associated with sexual dysfunction in HDPs receiving MMT. It deserves further investigation as to whether quitting smoking can improve the sexual function of methadone-maintained patients.

Relationship between e-waste recycling and human health risk in India: a critical review

Informal recycling of waste (including e-waste) is an emerging source of environmental pollution in India. Polychlorinated biphenyls (PCBs), polychlorinated diphenyl ethers (PBDEs), and heavy metals, among other substances, are a major health concern for workers engaged in waste disposal and processing, and for residents living near these facilities, and are also a detriment to the natural environment. The main objective of this review article was to evaluate the status of these impacts. The review found that, huge quantity of e-waste/waste generated, only a small amount is treated formally; the remainder is processed through the informal sector. We also evaluated the exposure pathways, both direct and indirect, and the human body load markers (e.g., serum, blood, breast milk, urine, and hair), and assessed the evidence for the association between these markers and e-waste exposure. Our results indicated that the open dumping and informal e-waste recycling systems should be replaced by the best available technology and environmental practices, with proper monitoring and regular awareness programs for workers and residents. Further and more detailed investigation in this area is also recommended.

Effects of Waterborne Lead Exposure in Mozambique Tilapia: Oxidative Stress, Osmoregulatory Responses, and Tissue Accumulation

We studied the oxidative stress and osmoregulatory damage as well as the accumulation of lead in Mozambique Tilapia Oreochromis mossambicus exposed to different sublethal concentrations-low, medium, and high (0.5, 2.5, and 5.0 mg/L)-of waterborne lead for 14 d in a semistatic condition. The accumulated levels of Na⁺, K⁺-ATPase, glutathione (GSH), and thiobarbituric acid reactive substances (TBARS) were determined from samples of gill, liver, intestine, brain, kidney, and muscle tissues. At the end of the experiment, the GSH levels of most tissues were higher in the treated group than in the control group (especially in the liver and kidney) but lower in the intestine. The levels of TBARS in the gill and brain tissues of the fish exposed to high lead doses were significantly higher than those of fish in the control group. Na⁺, K⁺-ATPase activity seemed to be significantly inhibited in the gill, intestine, and brain tissues across all treatment groups. At the end of the study, the total amount of lead that had accumulated within the various tissues ranked as follows: intestines > kidney > brain > gill > liver > muscle. Our findings suggest that sublethal concentrations of lead can disrupt the health of Mozambique Tilapia and cause oxidative stress and osmoregulatory damage.

Endocrine disruptive effects of cadmium on steroidogenesis: human adrenocortical carcinoma cell line NCI-H295R as a cellular model for reproductive toxicity testing

Cadmium (Cd) is a known endocrine disruptor with the ability to affect the production of hormones involved in the regulation of reproductive processes. In this study human adrenocortical carcinoma cell line NCI-H295R was used as an in vitro biological model to study the effect of cadmium (CdCl2) on steroidogenesis. The cell cultures were exposed to different concentrations of CdCl2 (1.90, 3.90, 7.80, 15.60, 31.20 and 62.50 μM) and compared to control (medium without CdCl2). Cell viability was measured by the metabolic activity (MTT) assay for estimation of mitochondria structural integrity. Quantification of sexual steroid production directly from aliquots of the medium was performed by enzyme linked immunosorbent assay (ELISA). Following 48 h culture of the cells in the presence of CdCl2 a concentration-dependent depletion in progesterone production was observed at the lower concentrations of CdCl2. The lowest amount of progesterone was significantly detected in groups with the higher doses (≥ 31.20 μM) of CdCl2, which elicited significant (P < 0.01) cytotoxic action, too. Cadmium decreased testosterone release in the whole applied range even at the lower concentration of CdCl2. The release of 17β-estradiol decreased as well, but the decline was less pronounced compared to decrease of progesterone and testosterone. The cytotoxic effect was significantly (P < 0.01) detected at all concentrations of CdCl2 (1.90-62.50 μM) used in the study. However, the cell viability remained relatively high (>75%) up to 7.80 μM of CdCl2 and significantly (P < 0.01) decreased at 15.60 μM and higher concentrations of CdCl2. These results suggest that cadmium has endocrine disruptive effects on sexual steroid synthesis even at very low concentrations.

Modulation of steroidogenic pathway in rat granulosa cells with subclinical Cd exposure and insulin resistance: an impact on female fertility

Changes in lifestyle lead to insulin resistance (IR) in females ultimately predisposing them towards infertility. In addition, cadmium (Cd), an environmental endocrine disruptor, is reported for detrimental effects on granulosa cells, thus leading to ovarian dysfunction. A combination of these factors, lifestyle and environment, seems to play a role in etiology of idiopathic infertility that accounts for 50% amongst the total infertility cases. To address this issue, we made an attempt to investigate the extent of Cd impact on insulin-resistant (IR) granulosa cells. We exposed adult female Charles Foster rats to dexamethasone and confirmed IR condition by fasting insulin resistance index (FIRI). On treatment of IR rats with Cd, the preliminary studies demonstrated prolonged estrous cyclicity, decrease in serum estradiol concentrations, abnormal histology of ovary, and increased granulosa cell death. Further gene and protein expression studies of steroidogenic acute regulatory (StAR) protein, 17β-hydroxysteroid dehydrogenase (17β-HSD), and cytochrome P450 aromatase (CYP19A1) were performed. Protein expression studies demonstrated significant decrease in treated groups when compared with control. Study revealed that, in spite of the molecular parameters being affected at varied level, overall ovarian physiology is maximally affected in IR and Cd coexposed group, thus mimicking the condition similar to those prevailing in infertile females.

Cumulative lead exposure and age at menopause in the Nurses' Health Study cohort

BACKGROUND

Early menopause has been associated with many adverse health outcomes, including increased risk of cardiovascular disease morbidity and mortality. Lead has been found to be adversely associated with female reproductive function, but whether exposures experienced by the general population are associated with altered age at menopause has not been explored.

OBJECTIVE

Our goal was to assess the association between cumulative lead exposure and age at natural menopause.

METHODS

Self-reported menopausal status and bone lead concentration measured with K-shell X-ray fluorescence-a biomarker of cumulative lead exposure-were obtained from 434 women participants in the Nurses' Health Study.

RESULTS

The mean (± SD) age at natural menopause was 50.8 ± 3.6 years. Higher tibia lead level was associated with younger age at menopause. In adjusted analyses, the average age of menopause for women in the highest tertile of tibia lead was 1.21 years younger (95% CI: -2.08, -0.35) than for women in the lowest tertile (p-trend = 0.006). Although the number of cases was small (n = 23), the odds ratio for early menopause (< 45 years of age) was 5.30 (95% CI: 1.42, 19.78) for women in the highest tertile of tibia lead compared with those in the lowest tertile (p-trend = 0.006). There was no association between patella or blood lead and age at menopause.

CONCLUSIONS

Our results support an association between low-level cumulative lead exposure and an earlier age at menopause. These data suggest that low-level lead exposure may contribute to menopause-related health outcomes in older women through effects on age at menopause.

CITATION

Eum KD, Weisskopf MG, Nie LH, Hu H, Korrick SA. 2014. Cumulative lead exposure and age at menopause in the Nurses' Health Study Cohort. Environ Health Perspect 122:229–234; http://dx.doi.org/10.1289/ehp.1206399

Cadmium impairment of reproduction in the female wall lizard Podarcis sicula

The exposure to environmental toxicants such cadmium (Cd) is an important research area in wildlife protection. In this study, the effect of Cd oral administration on the ovarian structure and function and on reproductive performance of the Italian wall lizard Podarcis sicula was studied. In vivo, adult female lizards were randomly assigned to three groups. Cd was given with food in single dose and in multiple doses 3 days/week for 4 weeks at dose of 1.0 μg/g body weight. Following euthanasia, the ovaries were removed and analyzed for morpho-functional changes. Results demonstrated that Cd increases prefollicular germ cells number; the evaluation of the number of follicles detects significantly higher number of atretic growing follicles, whereas primary follicles remain unchanged with respect to controls. After Cd treatments, follicles are deformed by the presence of large protrusions and a general dysregulation in the follicle organization is observed. The zona pellucida is also affected. Cd causes alteration in sugar metabolism and in metallothionein gene expression. Finally, Cd administration significantly reduces clutch size and dramatically increases embryo mortality. In conclusion, data here described show that Cd induces morpho-functional alterations in lizard follicles and indicates that these are responsible for a significant impairment of oogenesis. The effects of the dose are time independent, persisting essentially unchanged regardless of single or multiple administration, so it can be concluded that even occasional, sublethal Cd contamination may significantly impair reproductive performance in these animals.

Body fat percentage and hemoglobin levels are related to blood lead, cadmium, and mercury concentrations in a Korean Adult Population (KNHANES 2008-2010)

Body stores of lead, cadmium, and mercury are determined by the levels in the circulation, and their levels in blood may be related to hemoglobin levels and their absorption by soft tissue and bone. We investigated the association of body fat percentage, hemoglobin levels, and nutrient intakes with the blood concentrations of lead, cadmium, and mercury in a Korean adult population. This study was based on data from the 2008-2010 Korean National Health and Nutritional Examination Survey (n = 4,522, aged ≥ 20 years), which examined nutritional, biochemical, and health-related parameters. A multiple regression analysis after controlling for covariates of age, body mass index, residence area, education level, smoking and drinking status, and bone mineral density for men, with menopausal status added for women in addition to covariates for men indicated that blood lead and mercury levels were negatively associated with body fat percentage only in men, and blood lead, cadmium, and mercury levels were positively related to hemoglobin levels in both genders. Additionally, blood lead levels were negatively associated with fat and carbohydrate intake in both men and women but blood mercury levels were only in men, but not women. Sodium intake was a positive predictor of blood lead levels in both genders but was a positive predictor of blood cadmium levels only in men. In conclusion, body fat percentage and hemoglobin levels need to be recognized as confounding factors when considering blood levels of lead, cadmium and mercury as biomarkers for their exposure. Fat, carbohydrates and sodium intakes are also associated with heavy metal levels in the circulation.

Occupational exposures to chemicals as a possible etiology in premature ovarian failure: a critical analysis of the literature

Premature ovarian failure (POF) is a cause of infertility that affects about 1% of women under 40, and is considered as idiopathic in 75% of cases. An occupational chemical origin has been identified at least once with 2-bromopropane, but human studies are rare and experimental data are sparse. This review aims to carry out a critical synthesis of knowledge of the chemical agents likely to affect follicular stock in humans and/or animals, by direct toxicity to follicles, or by increasing their recruitments. Of 140 chemical agents (or groups) studied, 20 have been identified as potentially damaging to the ovarian reserve. For the majority of toxic agents, only experimental data are currently available. At least four of these agents are likely to lead to POF in descendents (ethylene glycol methyl ether; 2,2-bis(bromomethyl)-1,3-propanediol; benzo[a]pyrene; dimethylbenzantracene). We propose a strategy aiming to encourage progress in identifying occupational factors responsible for POF.

The association between cadmium, lead and mercury blood levels and reproductive hormones among healthy, premenopausal women

BACKGROUND

Cadmium, lead and mercury have been identified in human follicular fluid and ovarian tissue, and have been associated with adverse reproductive outcomes in epidemiologic studies; however, few studies have examined the relationship between blood metal levels and reproductive hormones.

METHODS

Among 252 premenopausal women aged 18-44 years, we examined the association between blood metal levels (cadmium, lead and mercury), cycle length, and reproductive hormones [FSH, LH, estradiol (E(2)) and progesterone] measured at clinically relevant time points in the menstrual cycle. The association between metal levels (continuous) and hormone levels was assessed using linear regression with hormone levels (natural) log transformed and the results interpreted as the percentage difference in hormone level per unit increase in metal level.

RESULTS

Median (interquartile range) cadmium, lead and mercury levels were 0.30 µg/l (0.19, 0.43), 0.87 µg/dl (0.68, 1.20) and 1.10 µg/l (0.58, 2.10), respectively. Each 1 µg/l increase in cadmium levels was associated with a 21% [95% confidence interval (CI): -2.9, 49.9] increase in early follicular phase E(2) levels after adjusting for age, race/ethnicity, lead and mercury. This association decreased when restricted to never smokers (10%; 95% CI: -19.5, 51.3). Cadmium was also associated with a non-significant 9% (95% CI: -0.2, 19.9), or 2.7 day, increase in cycle length among never smokers. No associations were observed between lead or mercury and the outcomes in adjusted analyses.

CONCLUSIONS

Further evaluation of the association between cadmium, E(2) and cycle length is warranted, taking into consideration cigarette smoke and its multiple components.

Association between lead and cadmium and reproductive hormones in peripubertal U.S. girls

BACKGROUND

Lead (Pb) and cadmium (Cd) are known reproductive toxicants thought to disrupt hormone production throughout sensitive developmental windows, although this has not been previously examined in nationally representative peripubertal children.

OBJECTIVES

We examined the association between blood Pb and urinary Cd concentrations and the reproductive hormones inhibin B and luteinizing hormone (LH) in girls 6-11 years of age who participated in the cross-sectional Third National Health and Nutrition Examination Survey (NHANES III) (1988-1994).

METHODS

Pb (micrograms per deciliter) was measured in whole blood, and Cd was measured in urine (nanograms per milliliter). Inhibin B (picograms per milliliter) and LH (milli-International units per milliliter) were measured in residual sera for 705 girls. Survey logistic regression was used to estimate associations with pubertal onset based on inhibin B concentration > 35 pg/mL or LH concentration > 0.4 mIU/mL, and multinomial logistic regression was used to estimate the association between Pb and increasing categories of hormone concentrations.

RESULTS

High Pb (≥ 5 µg/dL) was inversely associated with inhibin B > 35 pg/mL [odds ratio (OR) = 0.26; 95% confidence interval (CI), 0.11-0.60; compared with Pb < 1 µg/dL]. At 10 and 11 years of age, girls with low Pb (< 1 µg/dL) had significantly higher inhibin B than did girls with moderate (1-4.99 µg/dL) or high Pb (≥ 5 µg/dL). In the subsample of 260 girls with levels of inhibin B above the level of detection and using survey regression modeling, inhibin B levels were lower among girls with both high Pb and high Cd (ß= -0.52; 95% CI, -0.09 to -1.04) than among girls with high Pb alone (ß= -0.35; 95% CI, -0.13 to -0.57), relative to girls with low Pb and low Cd.

CONCLUSIONS

Higher Pb was inversely associated with inhibin B, a marker of follicular development, and estimated effects suggestive of pubertal delays appeared to be stronger in the context of higher Cd concentrations. These data underscore the importance of Pb and Cd as reproductive toxicants for young girls.

Cadmium chloride exposure modifies amino acid daily pattern in the mediobasal hypothalamus in adult male rat

The present study was conducted to investigate the possible effects of cadmium exposure on the daily pattern of aspartate, glutamate, glutamine, gamma-aminobutyric acid (GABA) and taurine levels in the mediobasal hypothalamus of adult male rats. For this purpose, animals were treated with cadmium at two different exposure doses (25 and 50 mg l(-1) of cadmium chloride, CdCl(2)) in the drinking water for 30 days. Control age-matched rats received CdCl(2)-free water. After the treatment, rats were killed at six different time intervals throughout a 24 h cycle. CdCl(2) exposure modified the amino acid daily pattern, as it decreased aspartate, glutamate, GABA and taurine levels at 12:00 h with both exposure doses employed. In addition, the treatment with 25 mg l(-1) of CdCl(2) induced the appearance of minimal values at 16:00 h and maximal values between 04:00 and 08:00 h for glutamate, and a peak of glutamine content at 20:00 h. The heavy metal also decreased GABA medium levels around the clock in the mediobasal hypothalamus. However, CdCl(2) did not alter the metabolic correlation between glutamate, aspartate, glutamine and GABA observed in control animals. These results suggest that CdCl(2) induced several alterations in aspartate, glutamate, glutamine, GABA and taurine daily pattern in the mediobasal hypothalamus and those changes may be related to alterations in hypothalamic function.

Effects of exposure to heavy metals on viability, maturation, fertilization, and embryonic development of buffalo (Bubalus bubalis) oocytes in vitro

The aim of the present study was to examine the effect of heavy metals, cadmium and lead, on buffalo oocyte viability and in vitro development. Oocytes were aspirated from ovaries of slaughtered buffaloes. Only viable and metabolically active oocytes with more than three layers of cumulus cell layers and homogeneous ooplasm were selected. Effects of nine concentrations (0, 0.005, 0.05, 0.5, 1.0, 1.5, 2.5, 5, and 10 microg/mL) of cadmium or lead on buffalo oocyte viability, morphological abnormities, maturation, and embryonic development in vitro were studied. Oocytes were cultured for 24 h and then checked for viability (0.05% trypan blue staining for 2 min), morphological abnormalities, and reduction assay by MTT test in experiment 1. The doses of cadmium and lead causing 100% oocyte death (1-day culture) were determined (experiment 2). In experiment 3, viable oocytes were matured in vitro in media containing different levels of cadmium or lead and then inseminated in vitro with frozen-thawed spermatozoa, and the resultant cleaved embryos were cultured in a control embryo culture medium for 8 days. In experiment 4, oocytes were cultured in control oocyte maturation medium, then fertilized, and the resultant embryos were cultured in media containing different levels of cadmium or lead for 8 days. The number of cells in the trophectoderm and inner cell mass (ICM) and the total cell counts (TCN) of blastocysts derived by in vitro culture of two- to four-cell-stage embryos (produced in control medium) in media containing 0, 0.005, 0.05, 0.5, and 1.0 microg/mL of cadmium or lead were analyzed by differential staining technique (experiment 5). Cadmium and lead were found to have a dose-dependent effect on viability, morphological abnormities, maturation, cleavage and morula/blastocyst yield, and blastocyst hatching. A significant decline in viability of oocytes was observed at 1.0 mg/mL cadmium or lead compared to the control group. The doses of cadmium and lead causing 100% oocyte death (1-day culture) were 18 and 32 microg/mL, respectively. Cadmium and lead at 1.0 and 2.5 microg/mL, respectively, caused a significant reduction of maturation of oocytes compared to the lower concentrations. No cleavage or morulae/blastocysts were produced when the oocytes/embryos were cultured in media containing 2.5 and 5.0 mg/mL of either cadmium or lead, respectively. Similarly, no morulae/blastocysts were produced from cleaved embryos cultured in media containing 2.5 and 5.0 microg/mL cadmium and lead, respectively. The developmental block, degeneration, and asynchronous divisions were higher in embryos exposed to cadmium than in those exposed to lead. TCN and number of cells in ICM were significantly lower in blastocysts derived from two- to four-cell-stage embryos cultured in media containing heavy metals. In conclusion, cadmium and lead lowered the viability and development of buffalo oocytes but at a concentration higher than that estimated in the body fluids and environment. Cadmium was found to be more ovotoxic than lead.

In vitro study on the effects of lead and mercury on porcine ovarian granulosa cells

The heavy metals lead (Pb) and mercury (Hg) pose potential risks to sustainability of environment and thus to our future generations. General objective of this in vitro study was to examine the secretory activity of porcine ovarian granulosa cells after Pb and Hg administration and to outline the potential intracellular mediators of its effects. For this purpose, release of insulin-like growth factor I (IGF-I) and steroid hormone progesterone (P(4)), expression of proliferation- related (cyclin B1) and apoptosis-related (caspase-3) peptides was examined in porcine ovarian granulosa cells after heavy metals administration. Obtained data indicate Pb-induced inhibition of IGF-I release at lower doses (0.063 mg/mL and 0.046 mg/mL) by ovarian granulosa cells. However, P(4) release was not influenced by Pb addition, while the expression of cyclin B1 and caspase-3 was induced by Pb addition. These results indicate that Pb can affect the pathway of proliferation and apoptosis of porcine ovarian granulosa cells through intracellular substances such as cyclin B1 and caspase-3. On the other hand, the P(4) release by ovarian granulosa cells of pregnant gilts was stimulated by experimental Pb administration at doses of 0.25 mg/mL and 0.063 mg/mL and experimental Hg administration at doses 0.25 mg/mL and 0.083 mg/mL. P(4) release by ovarian cells of pregnant gilts was not influenced by a combinatory dose of FSH (1.0 ng/mL) + Pb (0.083 mg/mL) + Hg (0.083 mg/mL) but it was inhibited by experimental administration of FSH (10 ng/mL) + Pb (0.25 ng/mL) + Hg (0.25 ng/mL). Possible involvement of heavy metals - Pb and Hg and pituitary hormone FSH, in the regulation of P(4) release by porcine ovarian granulosa cells of pregnant gilts was noted. Data obtained from in vitro studies suggest the dose dependent association of heavy metals administration with the hormonal release by porcine ovarian granulosa cells. This association also depended on pregnancy of the gilts.

Antioxidant status and selected biochemical parameters of porcine ovarian granulosa cells exposed to lead in vitro

The objective of this study was to determine the activity of superoxide dismutase (SOD), total antioxidant status (TAS) and release of calcium, phosphorus, magnesium, sodium, potassium, total lipids, totals proteins, glucose, cholesterol and triglycerides by porcine ovarian granulosa cells cultured in vitro after lead acetate administration. The parameters were analyzed using semi-automated clinical chemistry analyzer Microlab 300, microprocessor-controlled analyzer EasyLite and spectrophotometer Genesys 10. Cells were cultured with lead acetate trihydrate [Pb(CH(3)COO)(2).3H(2)O] as follows: group Max (5 mg Pb(CH(3)COO)(2).3H(2)O/10 mL), group A (2.5 mg/10 mL), group B (0.83 mg/10 mL), group C (0.625 mg/10 mL), group D (0.455 mg/10 mL) and the control group without lead exposure for 18 hrs. The highest TAS was estimated in the control group without lead treatment in comparison with other groups (MAX, A, B, C, D). Statistical analyses showed significantly lower value (P < 0.05) in group B. The activity of SOD was the lowest in the control group in comparison to those exposed to in vitro lead culture. A significant decrease (P < 0.05) of calcium content in group MAX in comparison with control group was determined. Release of phosphorus by ovarian granulosa cells was significantly lower (P < 0.05; 0.01; 0.001) in all the treated groups in comparison with control group. Lead was found to stimulate the release of magnesium and potassium by granulosa cells, but the increase remained statistically insignificant. The highest concentration of glucose was noted in control group, but the differences were not significant either. No significant differences (P > 0.05) were detected in concentration of other studied parameters among observed groups, too.

The effect of lead intoxication on endocrine functions

Studies on the effects of lead on the endocrine system are mainly based on occupationally lead-exposed workers and experimental animal models. Although evidence is conflicting, it has been reported that accumulation of lead affects the majority of the endocrine glands. In particular, it appears to have an effect on the hypothalamic-pituitary axis causing blunted TSH, GH, and FSH/LH responses to TRH, GHRH, and GnRH stimulation, respectively. Suppressed GH release has been reported, probably caused by reduced synthesis of GHRH, inhibition of GHRH release or reduced somatotrope responsiveness. Higher levels of PRL in lead intoxication have been reported. In short-term lead-exposed individuals, high LH and FSH levels are usually associated to normal testosterone concentrations, whereas in long-term exposed individuals' low testosterone levels do not induce high LH and FSH concentrations. These findings suggest that lead initially causes some subclinical testicular damage, followed by hypothalamic or pituitary disturbance when longer periods of exposure take place. Similarly, lead accumulates in granulosa cells of the ovary, causing delays in growth and pubertal development and reduced fertility in females. In the parenchyma of adrenals histological and cytological changes are demonstrated, causing changes in plasma basal and stress-mediated corticosterone concentrations and reduced cytosolic and nuclear glucocorticoid receptor binding. Thyroid hormone kinetics are also affected. Central defect of the thyroid axis or an alteration in T4 metabolism or binding to proteins may be involved in derangements in thyroid hormone action. Lead toxicity involves alterations on calcitropic hormones' homeostasis, which increase the risk of skeletal disorders.

Exposure to heavy metals (lead, cadmium and mercury) and its effect on the outcome of in-vitro fertilization treatment

We investigated the effect of lead, cadmium and mercury exposure on pregnancy and fertilization rate outcome among 619 Saudi women (age 19-50 years) who sought in-vitro fertilization (IVF) treatment between 2002 and 2003. The concentrations of lead, cadmium and mercury were measured in both blood and follicular fluids. At levels well below the current US occupational exposure limit guidelines (40microg/dL) and even less than the current Centers for Disease Control and Prevention level of concern for preventing lead poisoning in children (10microg/dL), blood lead level was negatively associated with fertilization outcome in both adjusted and unadjusted logistic regression models. We found that among various demographic, socioeconomic and environmental factors, fish consumption was positively associated with blood lead levels. These results support the hypothesis that a raised blood lead level affects infertility and intervention to reduce the lead exposure might be needed for women of reproductive age. The present results also revealed unexpected finding - the positive relationship between follicular cadmium levels and fertilization outcome, which points to the necessity for further investigation. Though adverse effect of mercury on pregnancy outcome or fertilization rate was not evident in this study, mercury5.8microg/L (EPA safety limit) was found in the blood and follicular fluid of 18.7% and 8.3% of the women, respectively. Concerns about its possible adverse effects on the physiology of reproduction or fetal development cannot be ruled out. It should be noted that skin-lightening creams and dental amalgam were important contributors to mercury exposure. Such finding is alarming and priority for further studies are, urgently, needed.

Effect of co-exposure to lead and cadmium on antioxidant status in rat ovarian granulose cells

The effects of combined exposure to lead and cadmium on granulose cells were studied. Adult female rats were treated i.p. with either lead acetate (LA) or cadmium acetate (CA) both, alone, or in combination at a dose of 0.05 mg/kg body weight on a daily basis for 15 days. Both metals were accumulated in the ovary after metal exposure. Metal exposure caused a decrease in reduced glutathione content along with elevated lipid peroxidation in all groups. Granulose cells of both cadmium as well as combination group demonstrated a maximum increase in lipid peroxides and catalase activity, along with decreased glutathione status and superoxide dismutase activities. Combined treated animals exhibited an intermediate effect in antioxidant status. However, "in vitro" exposure showed no significant change in antioxidant enzymes in all metal exposed cells. Data from the present study indicates that lead and cadmium in isolation and in combination cause oxidative stress. Lead and cadmium in combination do not show additive or synergistic effect indicating the competition between them due to similarity in electronic affinities. Present study highlights the effects of toxic metals that disturb membrane integrity of cells via ROS and thereby classifying mechanism for altered receptor binding, steroidogenesis, and hormone production.