Organochlorine pesticides in follicular fluid of women undergoing assisted reproductive technologies from central China

Methoxychlor induces oxidative stress and impairs early embryonic development in pigs

Introduction: Methoxychlor (MXC) is an organochlorine pesticide (OCP) that was formerly used worldwide as an insecticide against pests and mosquitoes. However, MXC is not biodegradable and has lipophilic characteristics; thus, it accumulates in organisms and affects reproductive function. MXC, as an estrogenic compound, promotes oxidative stress, induces oxidative stress damage to ovarian follicles, and causes miscarriages and stillbirths in females. In this research endeavor, our primary objective was to explore the ramifications of MXC regarding the developmental processes occurring during the initial stages of embryogenesis in pigs. Methods: In this study, we counted the blastocyst rate of early embryos cultured in vitro. We also examined the reactive oxygen species level, glutathione level, mitochondrial membrane potential, mitochondrial copy number and ATP level in four-cell stage embryos. Finally, apoptosis and DNA damage in blastocyst cells, as well as pluripotency-related and apoptosis-related genes in blastocyst cells were detected. The above experiments were used to evaluate the changes of MXC damage on early parthenogenetic embryo development. Results and Discussion: The results showed that early embryos exposed to MXC had a significantly lower cleavage rate, blastocyst rate, hatching rate, and total cell count compared with the control group. It was also of note that MXC not only increased the levels of reactive oxygen species (ROS), but also decreased the mitochondrial membrane potential (ΔΨm) and mitochondrial copy number during the development of early embryos. In addition, after MXC treatment, blastocyst apoptosis and DNA damage were increased, decreased cell proliferation, and the expression of pluripotency-related genes SOX2, NANOG, and OCT4 was down-regulated, while the expression of apoptosis-related genes BAX/BCL-2 and Caspase9 was up-regulated. Our results clearly show that MXC can have deleterious effects on the developmental processes of early porcine embryos, establishing the toxicity of MXC to the reproductive system. In addition, the study of this toxic effect may lead to greater concern about pesticide residues in humans and the use of safer pesticides, thus potentially preventing physiological diseases caused by chemical exposure.

Emerging bioanalytical sensors for rapid and close-to-real-time detection of priority abiotic and biotic stressors in aquaculture and culture-based fisheries

Abiotic stresses of various chemical contamination of physical, inorganic, organic and biotoxin origin and biotic stresses of bacterial, viral, parasitic and fungal origins are the significant constraints in achieving higher aquaculture production. Testing and rapid detection of these chemical and microbial contaminants are crucial in identifying and mitigating abiotic and biotic stresses, which has become one of the most challenging aspects in aquaculture and culture-based fisheries. The classical analytical techniques, including titrimetric methods, spectrophotometric, mass spectrometric, spectroscopic, and chromatographic techniques, are tedious and sometimes inaccessible when required. The development of novel and improved bioanalytical methods for rapid, selective and sensitive detection is a wide and dynamic field of research. Biosensors offer precise detection of biotic and abiotic stressors in aquaculture and culture-based fisheries within no time. This review article allows filling the knowledge gap for detection and monitoring of chemical and microbial contaminants of abiotic and biotic origin in aquaculture and culture-based fisheries using nano(bio-) analytical technologies, including nano(bio-)molecular and nano(bio-)sensing techniques.

Suspect and non-target screening of ovarian follicular fluid and serum - identification of anthropogenic chemicals and investigation of their association to fertility

In this work, ultra-high performance liquid chromatography-high resolution (Orbitrap) mass spectrometry-based suspect and non-target screening was applied to follicular fluid (n = 161) and serum (n = 116) from women undergoing in vitro fertilization in order to identify substances that may be associated with decreased fertility. Detected features were prioritized for identification based on (i) hazard/exposure scores in a database of chemicals on the Swedish market and an in-house database on per- and polyfluoroalkyl substances (PFAS); (ii) enrichment in follicular fluid relative to serum; and (iii) association with treatment outcomes. Non-target screening detected 20 644 features in follicular fluid and 13 740 in serum. Two hundred and sixty-two features accumulated in follicular fluid (follicular fluid: serum ratio >20) and another 252 features were associated with embryo quality. Standards were used to confirm the identities of 21 compounds, including 11 PFAS. 6-Hydroxyindole was associated with lower embryo quality and 4-aminophenol was associated with higher embryo quality. Overall, we show the complexity of follicular fluid and the applicability of suspect and non-target screening for discovering both anthropogenic and endogenous substances, which may play a role in fertility in women.

The Influence of Environmental Factors on Ovarian Function, Follicular Genesis, and Oocyte Quality

Endocrine-disrupting chemicals (EDCs) exist ubiquitously in the environment. Epidemiological data suggest that the increasing prevalence of infertility may be related to the numerous chemicals. Exposure to EDCs may have significant adverse impacts on the reproductive system including fertility, ovarian reserve, and sex steroid hormone levels. This chapter covers the common exposure ways, the origins of EDCs, and their effects on ovarian function, follicular genesis, and oocyte quality. Furthermore, we will review the origin and the physiology of ovarian development, as well as explore the mechanisms in which EDCs act on the ovary from human and animal data. And then, we will focus on the bisphenol A (BPA), which has been shown to reduce fertility and ovarian reserve, as well as disrupt steroidogenesis in animal and human models. Finally, we will discuss the future direction of prevention and solution methods.

Pesticides in human milk collected from Jinhua, China: Levels, influencing factors and health risk assessment

In China, many studies have been carried out on pesticide residues in human milk, yet all of them are on organochlorine pesticides (OCPs) and mostly focused on large, economically developed cities. In this study, 27 pesticides including OCPs, pyrethroid pesticides (PYRs) and organophosphate pesticides (OPPs) in human milk were investigated in Jinhua, an inland and medium sized city in China. Method based on QuEChERS extraction and gas chromatography-mass spectrometer (GC-MS) determination was adopted to analyze the above pesticide residues. The influencing factors as well as the health risks were also evaluated. Results show that PYRs and OPPs in human milk samples were both undetectable. Regarding OCPs, the detection rate of hexachlorobenzene (HCB), β-hexachlorocyclohexane (β-HCH) and p,p'-dichlorodiphenyl-dichloroethylene (p,p'-DDE) were 83.6%, 36.4% and 58.2%, respectively, and their mean value were 29.4, 32.0 and 85.2 ng/g lipid, respectively. p,p'-DDE levels in human milk was significantly (p < 0.05) related to maternal age, but no association was detected between OCPs residues and other factors (living environment, dietary habit, living style, etc.), suggesting that OCPs in human milk in Jinhua were originated from nonspecific source. All estimated daily intake of pesticides (EDI_pesticides) by infants were under the guideline suggested by Food and Agriculture Organization (FAO) and China Ministry of Health (CMH). Yet 9% of EDIs_HCB and 16% of EDIs_HCHs exceeded the guideline recommended by Health Canada. The associations between DDE residues and the delivery way as well as HCBs residues and the birth weight were seemly significant, yet the significance disappeared when consider age or gestational age as a cofounder, indicating that OCPs residue in mother's body in Jinhua has no obvious influence on fetus development and the delivery way.

Persistent environmental endocrine-disrupting chemicals in ovarian follicular fluid and in vitro fertilization treatment outcome in women

Several international organizations have recently highlighted endocrine-disrupting chemicals (EDCs) as factors of concern in human reproduction. Since successful reproduction is dependent on timely and appropriate action of hormones, disruption of the endocrine system could lead to difficulties in conceiving or carrying a pregnancy to term. EDCs are chemicals that disrupt the endocrine system by activating or inhibiting receptors of the endocrine system, and/or altering hormone receptor expression; signal transduction; epigenetic marks; hormone synthesis, transport, distribution, and metabolism; and the fate of hormone-producing cells. Due to the increasing production of industrial chemicals over the past century and their lenient control, EDCs are now common contaminants in the environment. Consequently, everyone faces a life-long exposure to mixtures of chemicals, some of which have been identified as EDCs. As birth rates in humans are declining and the use of assisted reproductive technologies increasing, it is timely to consider possible effects of EDCs on human reproduction and fertility. In this review, we focus on persistent EDCs, their occurrence in ovarian follicular fluid, and associations to treatment outcomes in assisted reproduction. Our summary shows that despite being banned decades ago, mixtures of persistent EDCs are still detected in the ovarian follicular fluid, demonstrating direct exposure of oocytes to these chemicals. In addition, there are several reported associations between exposure and worse outcome in in vitro fertilization. Further research is therefore warranted to prove causality, which will lead towards better regulation and exposure reduction.

Organochlorine pesticides exposure may disturb homocysteine metabolism in pregnant women

Maternal exposure to organochlorine pesticides (OCPs) has an adverse impact on maternal and fetal health, and excessive homocysteine is related to a variety of adverse pregnancy outcomes. Biomimetic studies suggest that OCPs interfere with folate-dependent pathways, but little evidence is available from studies with human subjects. This study explored whether exposure to OCPs interferes with the metabolism of homocysteine, which is folate dependent. A total of 313 pregnant women at 12-20 weeks gestation were recruited in Shanxi province, China, from 2014 to 2015. Plasma concentrations of 20 OCPs, including dichlorodiphenyltrichloroethane and metabolites (DDTs), hexachlorobenzene (HCB), and hexachlorocyclohexanes (HCHs), were analyzed by gas chromatography-mass spectrometry. Blood folate concentrations were analyzed by microbiological assay, and plasma homocysteine concentrations were determined by enzyme-linked immunosorbent assay. Information on demographics, lifestyle behaviors, and folic acid supplementation was collected by in-person interview. Of the women, 99% reported having taken folic acid supplements. Results of a logistic regression analysis showed that higher plasma levels of OCPs were associated with increased odds of higher plasma homocysteine after adjustment for potential confounding factors. Positive correlations were observed between plasma OCPs and plasma homocysteine concentrations: HCB (r = 0.176, p = 0.002), β-HCH (r = 0.172, p = 0.002), ρ,ρ'-DDE (r = 0.132, p = 0.020), ρ,ρ'-DDD (r = 0.161, p = 0.004), and ο,ρ'-DDT (r = 0.144, p = 0.011). Plasma concentrations of OCPs were negatively correlated with red blood cell (RBC) folate in the low-RBC-folate subgroup, but the correlations were not statistically significant. A positive correlation was observed between OCPs and homocysteine in the low-RBC-folate subgroup. These findings suggest that OCPs may disturb the folate-dependent homocysteine metabolism pathway.

Sperm Quality in Mouse After Exposure to Low Doses of TCDD

Background:

In the last decade, the harmful use of dioxin has been demonstrated in human health and in the whole environment. It is well known among scientists that 2, 3, 7, 8-tetrachloro dibenzo-p-dioxin (TCDD) is an environmental pollutant that causes endocrine disruption, which causes male reproductive toxicity.

Objective:

The objective of the present study was to evaluate the toxicity effect of low doses of TCDD in male CD1 mice.

Materials and Methods:

Three concentrations of TCDD (0.375, 0.75, 1.5 mg / kg) were analyzed and the effects on spermatozoa were evaluated 10 days after oral administration of the product. As bioindicators of TCDD toxicity, an exhaustive analysis of several spermatic parameters including motility, vitality, count, morphology and viability, flow cytometry was used to determine the affected sperm population by cytotoxicity and apoptosis. In addition, a morphometric analysis of testicles was performed.

Results:

The results show that the body weight of the treated animals was reduced in medium and high doses (0.75, 1.5 mg / kg) with respect to the control groups. In the groups treated with TCDD, the abnormal head of the sperm increased by 52.5% more than the control group. Significant differences in apoptosis were observed between the negative control and vehicle control, including the median dose (0.75 mg / kg).

Conclusion:

It is concluded that at these low doses there was an impact on the quality of the mouse sperm, adding an effect on apoptosis and cytotoxicity of sperm exposed to these doses of TCDD.

Persistent halogenated organic pollutants in follicular fluid of women undergoing in vitro fertilization from China: Occurrence, congener profiles, and possible sources

Analysis of persistent halogenated organic pollutants (HOPs) in human follicular fluid is important given previous reports of their adverse effects on the reproductivity of women. In the present work, HOPs, including polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs), were analyzed in 127 follicular fluid samples collected from patients who were undergoing in vitro fertilization in Central China. The concentrations of ∑₇BDEs (sum of BDE-28, -47, -99, -100, -153, -154, and -183) in follicular fluid ranged from not detected (n.d.) to 110 ng/g lipid weight (lw), with an average of 50 ± 24 ng/g lw. BDE-100 was suggested to be an indicator of BDE congeners in follicular fluid, with the highest concentrations and showing a significantly high correlation (p < 0.01) with ∑₇BDEs. Penta-BDE products were the principal source of PBDEs in follicular fluid samples. The concentrations of ∑₇CBs (CB-28, -52, -101, -118, -138, -153, and -180) in follicular fluids ranged from n.d. to 250 ng/g lw, with an average of 77 ± 69 ng/g lw. CB-28 and CB-52 were considered to be indicator CB congeners, with tri-CBs and tetra-CBs dominating in follicular fluid. No significant correlation was observed between patient age and PBDE or PCB concentrations in follicular fluid, indicating that age was not the controlling factor influencing the bioaccumulation of most HOPs in this study.

Association between Organochlorine Pesticide Levels in Breast Milk and Their Effects on Female Reproduction in a Taiwanese Population

Only few studies have focused on organochlorine pesticides (OCPs) in breast milk and the related health risks for women in Taiwan. Our goal is to examine breast milk OCPs and their associations with female reproductive function (infertility, gynecological diseases, and menstruation characteristics) as well as their correlation with sociodemographic parameters (age, pre-pregnant body mass index (BMI), annual incomes, population, birth year, and parity) and dietary habit. The breast milk samples were collected in southern Taiwan (n = 68) from 2013 to 2016 and the OCP residues were analyzed using high resolution gas chromatography with low resolution mass spectrometry (HRGC/LRMS). The results show that the most abundant OCP residues in the breast milk was ΣDDT with the geometric mean ± standard deviation of 9.81 ± 7.52 ng⁻¹ lipid⁻¹ followed by ΣHCH (0.539 ± 0.557 ng⁻¹·lipid⁻¹). In the principal component analysis, cis-chlordane (cis-CHL) and γ-HCH were found to be related to participants who received medical treatment for infertility, and 4,4′-DDT was associated with those who received gynecological surgery. The logistic regression showed that the odds ratio (OR) of log γ-hexachlorocyclohexane (γ-HCH) was higher for mothers who had received medical treatment for infertility than for the normal group (OR = 25.6, p = 0.035) after adjustments for age, pre-pregnant BMI, annual income, population (i.e., native-born Taiwanese), birth year, and parity. Cow milk and beef consumption as well as menstruation characteristics such as average menstrual period (>5 days), shortest menstrual period (<3 days), and women who had taken hormonal drugs were significantly associated to several OCP residues in the breast milk. In addition, ΣHCH including β-HCH and γ-HCH was correlated with annual family income and gravidity as well as cow milk and beef consumptions. Overall, γ-HCH exhibited a probable association with the infertility diseases of Taiwanese women, and dietary habit might play an important role in the female Taiwanese exposure to OCPs.

Chlorinated insecticides (toxaphene and endrin) affect oxytocin, testosterone, oestradiol and prostaglandin secretion from ovarian and uterine cells as well as myometrial contractions in cow in vitro

We examined the direct effects of toxaphene and endrin, chlorinated insecticides that are widespread in the environment, on myometrial contractions and on the secretion of hormones involved in regulating these contractions. Granulosa, luteal, endometrial and myometrial cells, and myometrial strips from non-pregnant cows were incubated with both insecticides at environmentally relevant doses. Toxaphene inhibited and endrin stimulated the secretion of testosterone and oestradiol from granulosa cells. Toxaphene also inhibited and endrin stimulated the expression of the mRNA encoding the precursor of oxytocin (OT), as well OT secretion in luteal cell cultures. Moreover, endrin increased OT secretion from granulosa cells. Neither insecticide exerted an effect on progesterone secretion from luteal cells. Only toxaphene decreased the secretion of prostaglandins (PGF2 and PGE2) from endometrial cells. Meanwhile, only endrin decreased basal myometrial contractions, which was accompanied by inhibition of PGF2 secretion from the myometrium. Both endrin and toxaphene also decreased the force of the OT-stimulated myometrial contractions, whereas only toxaphene inhibited the stimulatory effect of OT on the force of myometrial contractions. In contrast to endrin, toxaphene decreased synthesis and secretion of one of the primary stimulators of myometrial contractions (OT) and indirectly inhibited OT signal reception in the myometrium by reducing E2 secretion. Both insecticides decreased OT-stimulated myometrial contractions; therefore, they may inhibit further transmission of the OT signal. Moreover, endrin inhibited basal myometrial contractions, potentially resulting from reduced PGF2 secretion from the myometrium. Our data indicate the potential of these insecticides to disturb the course of the oestrous cycle or fertilisation.

Secretory function of ovarian cells and myometrial contractions in cow are affected by chlorinated insecticides (chlordane, heptachlor, mirex) in vitro

The aim of the study was to investigate the effect of chlordane, heptachlor and mirex, on hormonal regulation of the force of myometrial contractions. Myometrial, endometrial, granulosa and luteal cells as well as strips of myometrium from non-pregnant cows were incubated with three insecticides at environmentally relevant doses (0.1, 1 or 10ng/ml). None of the insecticides affected the viability of studied cells. Chlordane stimulated, while heptachlor and mirex inhibited, secretion of testosterone and estradiol from granulosa cells as well as secretion of progesterone from luteal cells, respectively. Secretion of oxytocin (OT) from granulosa cells was increased after incubation with all studied insecticides. Only mirex stimulated OT secretion from luteal cells, while heptachlor inhibited this effect. None of them affected synthesis of OT in luteal cells and prostaglandins (PGF2 and PGE2) secretion from uterine cells, except PGE2 secretion from endometrial cells was decreased when the cells were incubated with 0.1ng/ml of chlordane. Basal and OT-stimulated myometrial contractions were increased by mirex and decreased by heptachlor. The data show that the insecticides altered secretory function of ovarian cells. Heptachlor and mirex affected also myometrial contractions in vitro, but uterine secretion of prostaglandins were not involved in the mechanism of that adverse effect of insecticides. The data indicate on potential of these insecticides to disturb fertilisation, blastocyst implantation or even the length of gestation.

In utero methoxychlor exposure increases rat fetal Leydig cell number but inhibits its function

The objective of the present study is to determine whether in utero exposure to methoxychlor (MXC) affects rat fetal Leydig cell number, cell size, or functions. Pregnant Sprague Dawley dams were gavaged with corn oil (control, 0mg/kg/day MXC) or MXC at doses of 10, 50, or 100mg/kg/day from gestational day (GD) 12 to 21. The results show that MXC increased fetal Leydig cell numbers dose-dependently from 95±8×10³ cells/testis (control, mean±SEM) to 101±6, 148±22, and 168±21×10³ cells/testis, at the doses of 10, 50, and 100mg/kg, respectively. The increase of Leydig cell number by MXC was contributed by the increase of single cell population of Leydig cells, which increased from 21±2% of the control to 31±4%, 39±3%, or 40±4% at the doses of 10, 50 or 100mg/kg, respectively. Quantitative PCR results show that MXC increased Lhcgr expression at dose of 10mg/kg and Scarb1 and Cyp11a1 mRNA levels at doses of 50 and 100mg/kg. Immunohistochemical staining demonstrated the increase of CYP11A1 protein level from the dose of 10mg/kg. However, at the highest dose (100mg/kg) MXC reduced the testicular testosterone level and MXC (1μM) in vitro treatment also inhibited androgen production from isolated fetal Leydig cells. In conclusion, our findings indicate that at low dose MXC may increase fetal Leydig cell numbers and the expressions of some steroidogenic enzymes, but at high dose it reduces the testicular testosterone level leading to reproductive tract malformations in the male offspring.