Effect of pyrethroids on female genital system. Review

Ampligo® 150 ZC affect the expression of sex hormone receptors and cell proliferation marker in female rabbit ovary: Protective effects of thyme essential oil and vitamin C

Pesticides tend to cause serious reproductive defects, disturbing endocrine functions and reducing fertility, especially in females. The objective of this work was to identify the reprotoxic effects of Ampligo® 150 ZC (AP), a mixture formulation of lambda cyhalothrin and chlorantraniliprole, on the ovary of female rabbits (Oryctolagus cuniculus) and the possible protective effect of co-treatment with thyme essential oil (TEO), extracted from (Thymus vulgaris) species, and vitamin C (vit C). Twenty female rabbits were divided into four equal groups (n = 5): Control (distilled water), AP (20 mg/ kg bw of the insecticide mixture every other day, by gavage for 28 days), AP+TEO (20 mg/ kg bw of AP + 0.5 mg/ kg bw of TEO every other day), and AP+TEO+Vit C (20 mg/ kg bw of AP + 0.5 mg/ kg bw of TEO + 200 mg/ kg bw of vitamin C every other day). The effects were tested on body weight, ovary histomorphometry, and immunohistochemical expression of AFP, estrogen receptor (ER), and progesterone receptor (PR). The results revealed that AP decreased body and ovarian weights, caused ovarian histological damages, and increased collagen fiber deposition. The immunostaining of the ovary showed a significant (p < .001) increase in AFP and decrease in both ER and PR expressions. In the opposite, co-administration of TEO and vitamin C was effective in improving all caused alterations. In conclusion, combined use of TEO and vitamin C ameliorated the toxic effects of Ampligo® on the ovary in female rabbits.

Application of the Integrated Approach to Testing and Assessment (IATA) for evaluating endocrine disruption potential of selected pyrethroids by H295R steroidogenesis and ER/AR transcriptional activation

Pyrethroids, which are widely utilized in agriculture, household products, and public health for their potent insecticidal properties, elicit significant concerns regarding their potential endocrine-disrupting effects. However, previous studies have yielded inconsistent data, largely due to the absence of a standardized screening system. To address this limitation, the present study introduces an Integrated Approach to Testing and Assessment (IATA) to evaluate the endocrine-disrupting potential of pyrethroids, aligned with the Adverse Outcome Pathway (AOP) framework. Employing this IATA-based methodology, the endocrine-disrupting effects of five pyrethroids, allethrin, phenothrin, deltamethrin, cypermethrin, and lambda-cyhalothrin-were investigated, with a focus on hormone levels of 17β-estradiol (E2) and testosterone (T). Enzyme-linked immunosorbent assays (ELISA) and receptor transactivation assays were utilized to assess the direct receptor interactions and alternative disruption mechanisms. The results demonstrated that lambda-cyhalothrin and phenothrin significantly elevated E2 levels, while all tested compounds substantially reduced T levels. Notably, transactivation assays indicated that these pyrethroids function as estrogenic agonists and androgenic antagonists, suggesting their complex role in endocrine disruption. The IATA-based framework, incorporating steroidogenesis and receptor transactivation assays, provides a comprehensive approach for assessing endocrine disruption, enabling the early identification and prioritization of hazardous chemicals. By predicting adverse outcomes without relying on in vivo testing, this integrated approach enhances regulatory decision making, promotes public health protection, and supports ethical and efficient chemical risk assessment.

Preconception and first trimester exposure to pesticides and associations with stillbirth

Associations of pesticide exposures during preconception with stillbirth have not been well explored. We linked Arizona pesticide use records with birth certificates from 2006 to 2020 and estimated associations of living within 500 m of any pyrethroid, organophosphate (OP), or carbamate pesticide applications during a 90-day preconception window or the first trimester, with stillbirth. We considered a binary measure of exposure (any exposure), as well as log-pounds and log-acres applied within 500 m, in a negative control exposure framework with log-binomial regression. We included 1 237 750 births, 2290 stillbirths, and 27 pesticides. During preconception, any exposure to pesticides was associated with stillbirth, including cyfluthrin (risk ratio [RR] = 1.97; 95% CI, 1.17-3.32); zeta-cypermethrin (RR = 1.81; 95% CI, 1.20-2.74); OPs as a class (RR = 1.60; 95% CI, 1.16-2.19); malathion (RR = 2.02; 95% CI, 1.26-3.24); carbaryl (RR = 6.39; 95% CI, 2.07-19.74); and propamocarb hydrochloride (RR = 7.72; 95% CI, 1.10-54.20). During the first trimester, fenpropathrin (RR = 4.36; 95% CI, 1.09-17.50); permethrin (RR = 1.57; 95% CI, 1.02-2.42); OPs as a class (RR = 1.50; 95% CI, 1.11-2.01); acephate (RR = 2.31; 95% CI, 1.22-4.40); and formetanate hydrochloride (RR = 7.22; 95% CI, 1.03-50.58) were associated with stillbirth. Interpretations were consistent when using continuous measures of pounds or acres of exposure. Pesticide exposures during preconception and first trimester may be associated with stillbirth. This article is part of a Special Collection on Environmental Epidemiology.

Resmethrin induces implantation failure by disrupting calcium homeostasis and forcing mitochondrial defects in porcine trophectoderm and uterine luminal epithelial cells

Resmethrin, a type I pyrethroid insecticide, is frequently used globally in residential and farmland areas to control pests. Owing to the repeated administration of resmethrin, and particularly because of its lipophilic nature, residues have been detected in various environments, crops, and livestock. Previous studies have shown the adverse effects of resmethrin, including neurotoxicity and hepatotoxicity. However, the toxic effects of resmethrin on the female reproductive system have rarely been investigated. In the present study, we used two cell types, porcine trophectoderm (pTr) and porcine uterine luminal epithelial (pLE) cells, to examine the toxic effects of resmethrin on implantation and its mechanisms. Our study showed that resmethrin exposure induced apoptosis and inhibited cell cycle progression, thereby reducing the viability of both cell types. In addition, calcium homeostasis was disrupted following resmethrin treatment, and disrupted calcium homeostasis impaired the mitochondrial membrane potential and mitochondrial respiration. In addition to mitochondrial dysfunction, GRP75 and ER stress-related proteins were upregulated. Furthermore, the AKT and MAPK cascades were altered, and reactive oxygen species production and inflammation occurred after resmethrin treatment. Ultimately, through various mechanisms, resmethrin decreased the migratory abilities, and it could diminish the crosstalk between the two cell lines and lower the probability of successful implantation. Overall, we demonstrated that resmethrin interfered with the implantation process by triggering various toxic mechanisms. This study presents, for the first time, evidence regarding the mechanisms through which resmethrin exerts toxic effects on the female reproductive system, thereby raising awareness regarding the potential implications of its widespread use.

Reproductive toxicology: keeping up with our changing world

Reproductive toxicology testing is essential to safeguard public health of current and future generations. Traditional toxicological testing of male reproduction has focused on evaluating substances for acute toxicity to the reproductive system, with fertility assessment as a main endpoint and infertility a main adverse outcome. Newer studies in the last few decades have significantly widened our understanding of what represents an adverse event in reproductive toxicology, and thus changed our perspective of what constitutes a reproductive toxicant, such as endocrine disrupting chemicals that affect fertility and offspring health in an intergenerational manner. Besides infertility or congenital abnormalities, adverse outcomes can present as increased likelihood for various health problems in offspring, including metabolic syndrome, neurodevelopmental problems like autism and increased cancer predisposition, among others. To enable toxicologic studies to accurately represent the population, toxicologic testing designs need to model changing population characteristics and exposure circumstances. Current trends of increasing importance in human reproduction include increased paternal age, with an associated decline of nicotinamide adenine dinucleotide (NAD), and a higher prevalence of obesity, both of which are factors that toxicological testing study design should account for. In this perspective article, we highlighted some limitations of standard testing protocols, the need for expanding the assessed reproductive endpoint by including genetic and epigenetic sperm parameters, and the potential of recent developments, including mixture testing, novel animal models, in vitro systems like organoids, multigenerational testing protocols, as well as in silico modelling, machine learning and artificial intelligence.

Beta-cyfluthrin impairs implantation process by inducing mitochondrial defects and changes in reactive oxygen species-mediated signaling pathways in porcine trophectoderm and uterine luminal epithelial cells

Pyrethroid insecticides, such as beta-cyfluthrin, are used extensively globally, including in households and agriculture, and have been detected in the milk and urine of humans and cattle. Beta-cyfluthrin exhibits toxic effects, including neurotoxicity and male reproductive toxicity; however, few studies have investigated female reproductive toxicity despite its wide environmental distribution. The present study investigates effects of beta-cyfluthrin on implantation in porcine cells (pTr from the trophectoderm and pLE from the endometrial luminal epithelium). To identify the various physiological changes induced by beta-cyfluthrin, such as apoptosis and lipid peroxidation, flow cytometry analysis and immunofluorescence were performed with various reagents. In addition, the expression of genes and proteins associated with intracellular changes was confirmed using qRT-PCR and western blotting. Beta-cyfluthrin induced cell-cycle arrest and altered intracellular calcium flux. It also disrupted the mitochondrial function and promoted reactive oxygen species (ROS) production, leading to lipid peroxidation. Moreover, ROS induced by beta-cyfluthrin altered mitogen-activated protein kinase (MAPK) pathways and decreased cell migration capability. The expression levels of genes that are significant during early pregnancy were altered by beta-cyfluthrin in both cell lines. The changes resulted in apoptosis and diminished cell proliferation of pTr and pLE. Collectively, the results imply that beta-cyfluthrin disrupts the implantation process by affecting the physiology of the trophectoderm and endometrial luminal epithelial cells. The present study is the first to reveal the cellular mechanisms of beta-cyfluthrin on the female reproductive system and highlights the need for further in-depth research into its hazards.

Late gestational exposure to fenvalerate impacts ovarian reserve in neonatal mice via YTHDF2-mediated P-body assembly

Fenvalerate (FEN), a type II pyrethroid pesticide, finds extensive application in agriculture, graziery and public spaces for pest control, resulting in severe environmental pollution. As an environmental endocrine disruptor with estrogen-like activity, exposure to FEN exhibited adverse effects on ovarian functions. Additionally, the presence of the metabolite of FEN in women's urine shows a positive association with the risk of primary ovarian insufficiency (POI). In mammals, the primordial follicle pool established during the early life serves as a reservoir for storing all available oocytes throughout the female reproductive life. The initial size of the primordial follicle pool and the rate of its depletion affect the occurrence of POI. Nevertheless, there is very limited research about the impact of FEN exposure on primordial folliculogenesis. In this study, pregnant mice were orally administrated with 0.2, 2.0 and 20.0 mg/kg FEN from 16.5 to 18.5 days post-coitus (dpc). Ovaries exposed to FEN exhibited the presence of large germ-cell cysts that persist on 1 days post-parturition (1 dpp), followed by a significant reduction in the total number of oocytes in pups on 5 dpp. Moreover, the levels of m6A-RNA and its associated proteins METTL3 and YTHDF2 were significantly increased in the ovaries exposed to FEN. The increased YTHDF2 promoted the assembly of the cytoplasmic processing bodies (P-body) in the oocytes, accompanied with altered expression of transcripts. Additionally, when YTHDF2 was knocked-down in fetal ovary cultures, the primordial folliculogenesis disrupted by FEN exposure was effectively restored. Further, the female offspring exposed to FEN displayed ovarian dysfunctions reminiscent of POI in early adulthood, characterized by decreases in ovarian coefficient and female hormone levels. Therefore, the present study revealed that exposure to FEN during late pregnancy disrupted primordial folliculogenesis by YTHDF2-mediated P-body assembly, causing enduring adverse effects on female fertility.

Systematic analysis of circadian disrupting substances with a high-throughput zebrafish circadian behavior screening approach

Circadian rhythm aligns numerous biological functions in majority of animals. Aside from well-known external factors such as the light-dark cycle and temperature, circadian rhythm can also be regulated by rarely explored factors such as synthetic substances. Here, we established a circadian behavior screening approach utilizing zebrafish larvae model, which integrated high-throughput capabilities with automated batch processing. With this approach, we systematically analyzed the circadian disruptive effects of >60 synthetic substances commonly detected in aquatic environment by assessing both the circadian period length and amplitude of circadian behavior, with an exposure concentration set at 100 μg/L. Among tested substances, a series of circadian disrupting compounds (circadian disruptors) were identified. Several categories of the hit compounds can be recognized, such as phthalate (diisopentyl phthalate (DIPP), with 10.1 % and 49.6 % increases for circadian period length and amplitude, respectively), neuroactive substance (mirtazapine, with 10.6 % and 63.1 % increases, respectively), and biocides (thiamethoxam, with 100.3 % increase for amplitude). Among these compounds, DIPP increased circadian period length and amplitude with a high degree. Aside from DIPP, we further examined eleven other phthalates and demonstrated that benzyl butyl phthalate, diisobutyl phthalate and diisohexyl phthalate could also significantly increase the zebrafish circadian period length by 7.9 %, 3.7 % and 8.5 %, respectively. Collectively, the present findings substantiated the feasibility of this high throughput screening strategy for circadian disruptor's discovery and provided novel insights into understanding of the potential risks of synthetic substances.

Adsorption of Pyrethroids in Water by Calcined Shell Powder: Preparation, Characterization, and Mechanistic Analysis

Pyrethroids are common contaminants in water bodies. In this study, an efficient mussel shell-based adsorbent was prepared, the effects of factors (calcination temperature, calcination time, and sieved particle size) on the pyrethroid adsorption capacity from calcined shell powder were investigated via Box-Behnken design, and the prediction results of the model were verified. By characterizing (scanning electron microscopy, X-ray diffraction, Fourier infrared spectroscopy, and Brunauer-Emmett-Teller measurements) the adsorbent before and after the optimized preparation process, the results showed that calcined shell powder had a loose and porous structure, and the main component of the shell powder under optimized condition was calcium oxide. The adsorption mechanism was also investigated, and the analysis of adsorption data showed that the Langmuir, pseudo second-order, and intra-particle diffusion models were more suitable for describing the adsorption process. The adsorbent had good adsorption potential for pyrethroids, the adsorption capacity of the two pesticides was 1.05 and 1.79 mg/g, and the removal efficiency was over 40 and 70% at the maximum initial concentration, respectively.

Bacillus thuringiensis affects reproductive capacity of adult rat offspring

We investigated the effects of B. thuringiensis-based biological insecticides, XenTari and Dipel, and deltamethrin on the reproductive development of pups of pregnant rats. Twenty 90-day-old pregnant rats were divided randomly onto four equal groups: control group (GC) administered only water; XenTari group (GX) administered 1 mg XenTari (containing Cry1Ac toxin of B. thuringiensis)/100 g body weight; Dipel group (GDi) administered 1 mg Dipel (containing Cry1Aa, Cry1Ab and Cry1Ac toxins of B. thuringiensis)/100 g body weight; and a deltamethrin group (GDe) administered 2 mg deltamethrin (0.08 ml Keshet 25EC)/kg body weight as a positive control. Insecticides were administered by gavage at doses of 1 mg/100 g/day (GX and GDi), and 2 mg/kg/day (GDe) during pregnancy and lactation. Treatment with both biologic and synthetic insecticides reduced the weight gain of the mothers. The biological insecticides reduced the number, weight and length, and increased malformation and mortality of the offspring. In female offspring for all three groups administered insecticides, opening of the vagina was delayed, metestrus was increased and estrogen and progesterone levels were reduced compared to proestrus, estrus and metestrus of the cycle. The ovaries of female offspring of all three groups administered insecticides contained numerous tertiary and atretic follicles, few corpora lutea, primary and secondary follicles, and reduced estrogen receptors compared to controls. In male offspring, all three groups exposed to insecticides exhibited reduced testosterone levels. Histopathological changes in the testes including vacuolation and desquamation of the seminiferous epithelium were observed only in the GX and GDi groups. The number of androgen receptors was reduced significantly in the testes and testicular morphometry revealed reduced tubule diameter, height of the seminiferous epithelium and total tubule length compared to the control. The biological insecticides, XenTari and Dipel, administered in sublethal doses to pregnant rats, caused reproductive changes in the offspring similar to those of the insecticide, deltamethrin.

Androgen receptor signaling and pyrethroids: Potential male infertility consequences

Infertility is a global health concern inflicting a considerable burden on the global economy and a severe socio-psychological impact. Approximately 15% of couples suffer from infertility globally, with a male factor contribution of approximately 50%. However, male infertility remains largely unexplored, as the burden of infertility is mostly assigned to female people. Endocrine-disrupting chemicals (EDCs) have been proposed as one of the factors causing male infertility. Pyrethroids represent an important class of EDCs, and numerous studies have associated pyrethroid exposure with impaired male reproductive function and development. Therefore, the present study investigated the potentially toxic effects of two common pyrethroids, cypermethrin and deltamethrin, on androgen receptor (AR) signaling. The structural binding characterization of cypermethrin and deltamethrin against the AR ligand-binding pocket was performed using Schrodinger's induced fit docking (IFD) approach. Various parameters were estimated, such as binding interactions, binding energy, docking score, and IFD score. Furthermore, the AR native ligand, testosterone, was subjected to similar experiments against the AR ligand-binding pocket. The results revealed commonality in the amino acid-binding interactions and overlap in other structural parameters between the AR native ligand, testosterone, and the ligands, cypermethrin and deltamethrin. The estimated binding energy values of cypermethrin and deltamethrin were very high and close to those calculated for AR native ligand, testosterone. Taken together, the results of this study suggested potential disruption of AR signaling by cypermethrin and deltamethrin, which may result in androgen dysfunction and subsequent male infertility.

Early pregnancy exposure to beta-cypermethrin compromises endometrial decidualisation in mice via downregulation of cyclin D3, CDK4/6, and p21

Beta-cypermethrin (β-CYP) is a highly effective broad-spectrum insecticide that can potentially affect female reproduction. However, little is known about the effect of β-CYP on uterine decidualisation, which is a vital process by which the uterus provides a suitable microenvironment for pregnancy maintenance. Therefore, we focused on the effect and mechanism of β-CYP on endometrial decidualisation during early pregnancy in mice. The results indicated that the expression levels of HOXA10, BMP2, and IGFBP1 was significantly downregulated in the decidual tissue and primary endometrial stromal cells of pregnant and pseudopregnant mice following β-CYP treatment. Serum E₂ concentration was significantly increased, whereas P₄ concentration and oestrogen receptor (ERα) and progesterone receptor (PRA) expression were significantly downregulated following β-CYP exposure. The number of polyploid decidual cells was lower in the β-CYP-treated group. Furthermore, β-CYP significantly downregulated the protein expression levels of CDK4 and CDK6, and the mRNA expression levels of cyclin D3 and p21. The number of foetuses per female in the first litter was markedly reduced following exposure to β-CYP. In summary, early pregnancy exposure to β-CYP may result in defective endometrial decidualisation via compromised proliferation of uterine stromal cells and reduced expressions of cyclin D3, CDK4/6, and p21 in mice.

Associations between pyrethroid exposure and serum sex steroid hormones in adults: Findings from a nationally representative sample

BACKGROUND

Pyrethroids have been considered as potential endocrine-disrupting chemicals and have been shown to be associated with endocrine-related health outcomes. However, limited studies directly explored the link between pyrethroid exposure and sex hormones in the general population.

OBJECTIVES

To explore the associations between exposure to pyrethroids and serum sex steroid hormones in adults.

METHODS

We evaluated the cross-sectional associations in 1235 adults aged ≥20 years who had been assigned to the National Health and Nutrition Examination Survey (NHANES) 2013-2014. The urinary concentration of 3-phenoxybenzoic acid (3-PBA) was applied as a biomarker of human pyrethroid exposure levels. Information on sex steroid hormones, including total testosterone (TT), estradiol (E2), and sex hormone-binding globulin (SHBG) in serum were measured. Free androgen index (FAI) and the ratio of TT to E2 (TT/E2) were also calculated. The percent changes with 95% confidence intervals (CIs) for a doubling of 3-PBA concentrations in the serum sex hormone levels were estimated using generalized linear regression models.

RESULTS

The overall median concentrations of creatinine-adjusted 3-PBA were 0.58 μg/g creatinine, and 90.0% of adults had a detectable level of 3-PBA. In females, every two-fold increase in 3-PBA was associated with 4.34% (95% CI: 1.58%, 7.18%) higher levels of TT and 4.05% (95% CI: 7.03%, 1.16%) higher levels of SHBG, respectively. In males, a doubling in 3-PBA was associated with 3.02% (95% CI: 1.21%, 4.86%) increase in SHBG but 1.85% (-3.59%, -0.07%) decrease in FAI, respectively. In addition, significant non-linear associations of 3-PBA with SHBG in both males and females and TT in females were observed.

CONCLUSIONS

Environmental pyrethroid exposure was associated with altered sex hormones in adults. This study provides important epidemiological evidence for the association of pyrethroids with endocrine disruption.

Correlation analysis of serum reproductive hormones and metabolites during multiple ovulation in sheep

BACKGROUND

The establishment of non-invasive diagnostic method for multiple ovulation prediction is helpful to improve the efficiency of multiple ovulation. The blood hormones and metabolites would be suitable indexes for this subject.

METHODS

In this study, 86 estrus ewes (65 of induced estrus (IE) and 21 of spontaneous estrus (SE)) were selected and the blood samples were collected at the day before follicle-stimulating hormone (FSH) injection (1^st) and before artificial insemination (2^nd). The serum reproductive hormones ofFSH, luteinizing hormone (LH), 17β-Estradiol (E2), progesterone (P4) and anti-Mullerian hormone (AMH) were measured through enzyme linked immunosorbent assay (ELISA) and the untargeted metabolomics analysis was processed through LC-MS/MS. The embryos were collected after 6.5 days of artificial insemination.

RESULTS

In total, 975 and 406 embryos were collected in IE and SE group, respectively. The analysis of reproductive hormones showed that concentrations of FSH, E2 and AMH were positive correlated with the embryo yield while concentrations of LH and P4 were negative correlated in both group at 1^st detection. At 2^nd detection, the trends of reproductive hormones were similar with 1^st except P4, which was positive correlated with embryo yield. The metabolomics analysis showed that 1158 metabolites (721 in positive iron mode and 437 in negative iron mode) were detected and 617 were annotated. In 1^st comparation of high and low embryonic yield populations, 56 and 53 differential metabolites were identified in IE and SE group, respectively. The phosphatidyl choline (PC) (19:0/20:5) and PC (18:2/18:3) were shared in two groups. In 2^nd comparation, 48 and 49 differential metabolites were identified in IE and SE group, respectively. The PC (18:1/18:2) and pentadecanoic acid were shared. Most differential metabolites were significantly enriched in amino acid, fatty acid metabolism, digestive system secretion and ovarian steroidogenesis pathways.

CONCLUSIONS

This study showed that FSH, P4, AMH, the PC relevant metabolites and some anomic acids could be potential biomarkers for embryonic yield prediction in ovine multiple ovulation. The results would help to explain the relation between blood material and ovarian function and provide a theoretical basis for the multiple ovulation prediction.

Exposures to deltamethrin on immature Chironomus columbiensis drive sublethal and transgenerational effects on their reproduction and wing morphology

Sublethal exposure to insecticides can trigger unintended responses in non-target insects that may disrupt reproductive and developmental performances of these organisms. Here, we assessed whether sublethal exposure to the pyrethroid insecticide deltamethrin in early life had sublethal and transgenerational effects on the reproduction (i.e., fecundity and fertility) and wing morphology of Chironomus columbiensis, an aquatic insect used as a water quality indicator. We first conducted concentration-response bioassays to evaluate the susceptibility of C. columbiensis larvae to deltamethrin. Our results revealed that deltamethrin toxicity was approximately 7-fold higher when C. columbiensis larvae where exposed to 96 h (LC₅₀ = 0.17 [0.15-0.20] μg/L) than to 24 h (LC₅₀ = 1.17 [0.97-1.43] μg/L). Furthermore, the sublethal exposures (at LC₁ = 0.02 μg/L or LC₁₀ = 0.05 μg/L) of immature C. columbiensis resulted in lower fecundity (e.g., reduced eggs production) and morphometric variation wing shapes. Further reduction in fertility rates (quantity of viable eggs) occurred at deltamethrin LC₁₀ (0.05 μg/L). Almost 80% of the fecundity was recovered with only a single recovery generation; however, two subsequent recovery generations were not sufficient to fully recover fecundity in C. columbiensis. Specimens recovered from 98.5% of wing morphometric variation after two consecutive generations without deltamethrin exposure. Collectively, our findings demonstrates that sublethal exposure to synthetic pyrethroids such as deltamethrin detrimentally affect the reproduction and wing shape of C. columbiensis, but also indicate that proper management of these compounds (e.g., concentration and frequency of application) would suffice for these insects' population recovery.

Motor, memory, and anxiety-like behavioral impairments associated with brain-derived neurotrophic factor and dopaminergic imbalance after inhalational exposure to deltamethrin

Believed to cause damage to the nervous system and possibly being associated with neurodegenerative diseases, deltamethrin (DM) is a type II pyrethroid used in pest control, public health, home environment, and vector control. The objective of this study was to evaluate the motor, cognitive and emotional changes associated with dopaminergic and BDNF imbalance after DM exposure in rats. Sixty Wistar rats (9-10 months-old) were used, under Ethics Committee on Animal Research license (ID 19/2017). The animals were randomly divided into four groups: control (CTL, 0.9% saline), DM2 (2mg DM in 1.6mL 0.9% saline), DM4 (4mg of DM in 1.6mL of 0.9% saline), and DM8 (8mg of DM in 1.6mL of 0.9% saline). DM groups were submitted to 9 or 15 inhalations, one every 48hours. Half of the animals from each group were randomly selected and perfused 24hours after the 9th or 15th inhalation. Throughout the experiment, the animal's behavior were evaluated using catalepsy test, open field, hole-board test, Modified Elevated Plus Maze, and social interaction. At the end of the experiments, the rats were perfused transcardially and their brains were processed for Tyrosine Hydroxylase (TH) and Brain derived neurotrophic factor (BDNF) immunohistochemistries. The animals submitted to 9 inhalations of DM showed a reduction in immunoreactivity for TH in the Substantia nigra pars compacta (SNpc), ventral tegmental area (VTA), and dorsal striatum (DS) areas, and an increase in BDNF in the DS and CA1, CA3 and dentate gyrus (DG) hippocampal areas. Conversely, the animals submitted to 15 inhalations of DM showed immunoreactivity reduced for TH in the SNpc and VTA, and an increase in BDNF in the hippocampal areas (CA3 and DG). Our results indicate that the DM inhalation at different periods induce motor and cognitive impairments in rats. Such alterations were accompanied by dopaminergic system damage and a possible dysfunction on synaptic plasticity.

Occurrence of pyrethroids in the atmosphere of urban areas of Southeastern Brazil: Inhalation exposure and health risk assessment

The occurrence of organochlorine pesticides (OCPs) used decades ago for vector control in urban areas is still reported as a threat to human health. Pyrethroids emerged as a replacement for OCPs in sanitary campaigns and are currently the main insecticides used for vector control worldwide, with prominent use as agricultural and household insecticides, for veterinary and gardening purposes, and as wood preservative. This study aimed to assess the occurrence, seasonal variation, and potential sources of pyrethroids in ambient air of two urban regions of Southeastern Brazil, along with the potential health risks to local populations via inhalation exposure. Pyrethroids were sampled by polyurethane foam passive air samplers and their concentrations were determined by gas chromatography coupled with electron capture negative ionization mass spectrometry (GC/ECNI-MS). Atmospheric pyrethroid concentrations (hereinafter reported in pg m^-3) were considerably higher than those reported by previous studies worldwide. Cypermethrin (median: 2446; range: 461-15 125) and permethrin (655; 19-10 328) accounted for 95% of the total measured pyrethroids in ambient air. The remaining fraction comprised smaller amounts of bifenthrin (46; <limit of detection (LOD)-5171), deltamethrin (58; <LOD-564), phenothrin (7; <LOD-22) and fenvalerate (0.3; <LOD-3). Bifenthrin, deltamethrin and permethrin were linked to local sources, while cypermethrin, fenvalerate and phenothrin had more prominent regional contributions. In broad terms, most pyrethroids showed no clear seasonal trend. The concentrations and hazard quotients (HQs) showed the following order of occurrence and magnitude: urban > urban-industrial > background areas. HQs increased with decreasing age group, but deterministic and probabilistic estimates did not identify direct health risks for any group. Nevertheless, since only inhalation exposure was considered in this work, other pathways should be investigated to provide a more comprehensive risk assessment of the human exposure to pyrethroids.

Reproductive Health Risks Associated with Occupational and Environmental Exposure to Pesticides

A marked reduction in fertility and an increase in adverse reproductive outcomes during the last few decades have been associated with occupational and environmental chemical exposures. Exposure to different types of pesticides may increase the risks of chronic diseases, such as diabetes, cancer, and neurodegenerative disease, but also of reduced fertility and birth defects. Both occupational and environmental exposures to pesticides are important, as many are endocrine disruptors, which means that even very low-dose exposure levels may have measurable biological effects. The aim of this review was to summarize the knowledge collected between 2000 and 2020, to highlight new findings, and to further interpret the mechanisms that may associate pesticides with infertility, abnormal sexual maturation, and pregnancy complications associated with occupational, environmental and transplacental exposures. A summary of current pesticide production and usage legislation is also included in order to elucidate the potential impact on exposure profile differences between countries, which may inform prevention measures. Recommendations for the medical surveillance of occupationally exposed populations, which should be facilitated by the biomonitoring of reduced fertility, is also discussed.

In vitro toxicological assessment of flumethrin's effects on MCF-7 breast cancer cells

Pyrethroid pesticides are frequently used for household insect control of insects and in agriculture and livestock. Flumethrin is a pyrethroid that is used against ectoparasites in many animals. The goal of this study was to evaluate the cytotoxic, apoptotic, genotoxic, and estrogenic effects of flumethrin on the mammalian breast cancer cell line (MCF-7). Compared with control groups, a dose-dependent decrease was observed in cell viability at concentrations of 100 µM and higher. The cytotoxic and apoptotic effects detected by LDH assay and AO/EtBr staining increased significantly at a concentration of 1000 µM. The expression of BCL2, which is an anti-apoptotic gene, significantly decreased, whereas BAX, TP53, and P21 expression significantly increased. The results of a comet assay indicated that flumethrin significantly changed tail length, tail % DNA, tail moment, and Olive tail moment in concentrations above 1 and 10 µM. In addition, a 0.1 µM concentration of flumethrin affected ERα receptor mediated cell proliferation and increased transcription of estrogen-responsive pS2 (TFF1) and progesterone receptor (PGR) genes. As a result, flumethrin-induced apoptosis and cytotoxicity at a high concentration, while induced genotoxicity even at lower concentrations. Flumethrin is an endocrine disrupting insecticide with estrogenic effects at very low concentrations.

Pyrethroid based pesticides - chemical and biological aspects

Human and animal welfare primarily depends on the availability of food and surrounding environment. Over a century and half, the quest to identify agents that can enhance food production and protection from vector borne diseases resulted in the identification and use of a variety of pesticides, of which the pyrethroid based ones emerged as the best choice. Pesticides while improved the quality of life, on the other hand caused enormous health risks. Because of their percolation into drinking water and food chain and usage in domestic settings, humans unintentionally get exposed to the pesticides on a daily basis. The health hazards of almost all known pesticides at a variety of doses and exposure times are reported. This review provides a comprehensive summation on the historical, epidemiological, chemical and biological (physiological, biochemical and molecular) aspects of pyrethroid based insecticides. An overview of the available knowledge suggests that the synthetic pyrethroids vary in their chemical and toxic nature and pose health hazards that range from simple nausea to cancers. Despite large number of reports, studies that focused on identifying the health hazards using doses that are equivalent or relevant to human exposure are lacking. It is high time such studies are conducted to provide concrete evidence on the hazards of consuming pesticide contaminated food. Policy decisions to decrease the residual levels of pesticides in agricultural products and also to encourage organic farming is suggested.

The deleterious toxic effects of bifenthrin on male fertility

Bifenthrin (BF), a broad-spectrum synthetic pyrethroid insecticide, has been generally used to eradicate harmful insects. However, according to the U.S. EPA, BF has been classified as a "Class C" carcinogenic ingredient. Furthermore, a previous study reported that BF was considered as endocrine-disrupting chemicals and causes reproductive toxicity in mammals. Despite the various effects of BF, there is a scarcity of studies about its adverse effects on male fertility. Therefore, this study was conducted to determine the effects of BF on sperm functions at various concentrations (0.1, 1, 10, and 100 μM), including a control. Sperm motility and kinematics, capacitation status, intracellular ATP levels, cell viability, PKA activation, and protein tyrosine phosphorylation were measured. Moreover, fertilization and early embryonic development were examined through in vitro fertilization. Results showed that sperm motility and kinematic parameters were significantly decreased at a high BF concentration. Consequently, the sperm capacitation status exhibited significant alteration according to the treatment concentration. Intracellular ATP levels were significantly decreased at 10 and 100 μM treatment concentrations. Moreover, the levels of phospho-PKA substrates were significantly increased in a dose-dependent manner. In contrast, the levels of phospho-tyrosine substrates were significantly decreased at 10 and 100 μM treatment concentrations. BF treatment also diminished the rate of blastocyst formation. Altogether, our results demonstrated that BF causes detrimental effects on sperm function and can influence fertilization. Therefore, our study results might be helpful in understanding the adverse effects of BF on male fertility.

Rhamnolipids on Aedes aegypti larvae: a potential weapon against resistance selection

The resistance of Aedes aegypti to chemical insecticides has been reported and our work proposes the use of biosurfactants as an alternative larvicide. We evaluated the effect of rhamnolipids against larvae of pyrethroid-resistant and susceptible A. aegypti strains. Time-mortality and sublethal effects were evaluated via survival analysis and swimming behavior, respectively. Rhamnolipids showed larvicidal effect at all tested concentrations. Rhamnolipids at 300 mg L^-1 killed 100% of both susceptible and resistant larvae within 24 h of exposure and 99% after 30-days stored (pyrethroid-susceptible larvae). Regarding the sublethal effects, the swimming rate was reduced in 50 and 100 mg L^-1 of rhamnolipids in grouped (pyrethroid-susceptible) larvae. Rhamnolipids at 50 mg L^-1 reduced the distance and speed and increased the number of stops and resting time of individualized pyrethroid-susceptible larvae. The larvicidal effect of the rhamnolipids evaluated demonstrates that these compounds represent an alternative to control A. aegypti.

Endocrine disrupting chemicals: Impacts on human fertility and fecundity during the peri-conception period

It is becoming increasingly difficult to avoid exposure to man-made endocrine disrupting chemicals (EDCs) and environmental toxicants. This escalating yet constant exposure is postulated to partially explain the concurrent decline in human fertility that has occurred over the last 50 years. Controversy however remains as to whether associations exist, with conflicting findings commonly reported for all major EDC classes. The primary aim of this extensive work was to identify and review strong peer-reviewed evidence regarding the effects of environmentally-relevant EDC concentrations on adult male and female fertility during the critical periconception period on reproductive hormone concentrations, gamete and embryo characteristics, as well as the time to pregnancy in the general population. Secondly, to ascertain whether individuals or couples diagnosed as sub-fertile exhibit higher EDC or toxicant concentrations. Lastly, to highlight where little or no data exists that prevents strong associations being identified. From the greater than 1480 known EDCs, substantial evidence supports a negative association between exposure to phthalates, PCBs, PBDEs, pyrethroids, organochloride pesticides and male fertility and fecundity. Only moderate evidence exists for a negative association between BPA, PCBs, organochloride pesticides and female fertility and fecundity. Overall fewer studies were reported in women than men, with knowledge gaps generally evident for both sexes for all the major EDC classes, as well as a paucity of female fertility studies following exposure to parabens, triclosans, dioxins, PFAS, organophosphates and pyrethroids. Generally, sub-fertile individuals or couples exhibit higher EDC concentrations, endorsing a positive association between EDC exposure and sub-fertility. This review also discusses confounding and limiting factors that hamper our understanding of EDC exposures on fertility and fecundity. Finally, it highlights future research areas, as well as government, industry and social awareness strategies required to mitigate the negative effects of EDC and environmental toxicant exposure on human fertility and fecundity.

Pyrethroids Toxicity to Male Reproductive System and Offspring as a Function of Oxidative Stress Induction: Rodent Studies

Pyrethroids may be related to male reproductive system damage. However, the results of many previous studies are contradictory and uncertain. Therefore, a systematic review and a meta-analysis were performed to assess the relationship between pyrethroid exposure and male reproductive system damage. A total of 72 articles were identified, among which 57 were selected for meta-analysis, and 15 were selected for qualitative analysis. Pyrethroid exposure affected sperm count (SMD= -2.0424; 95% CI, -2.4699 to -1.6149), sperm motility (SMD=-3.606; 95% CI, -4.5172 to -2.6948), sperm morphology (SMD=2.686; 95% CI, 1.9744 to 3.3976), testis weight (SMD=-1.1591; 95% CI, -1.6145 to -0.7038), epididymal weight (SMD=-1.1576; 95% CI, -1.7455 to -0.5697), and serum testosterone level (SMD=-1.9194; 95% CI, -2.4589 to -1.3798) in the studies of rats. We found that gestational and lactational exposure to pyrethroids can reduce sperm count (SMD=1.8469; 95% CI, -2.9010 to -0.7927), sperm motility (SMD=-2.7151; 95% CI, -3.9574 to -1.4728), testis weight (SMD=-1.4361; 95% CI, -1.8873 to -0.9848), and epididymal weight (SMD=-0.6639; 95% CI, -0.9544 to -0.3733) of F1 offspring. Exposure to pyrethroids can increase malondialdehyde (SMD=3.3451; 95% CI 1.9914 to 4.6988) oxide in testes and can reduce the activities of glutathione (SMD=-2.075; 95% CI -3.0651 to -1.0848), superoxide dismutase (SMD=-2.4856; 95% CI -3.9612 to -1.0100), and catalase (SMD=-2.7564; 95% CI -3.9788 to -1.5340). Pyrethroid exposure and oxidative stress could damage male sperm quality. Gestational and lactational pyrethroid exposure affects the reproductive system of F1 offspring.

Bio-accumulation of organic contaminants in Indo-Pacific humpback dolphins: Preliminary unique features of the brain and testes

There is little information about the residue levels and congener composition of organic contaminants (OCs) in cetaceans. In the present study, we investigated the polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) in the blubber, blood, brain and testes of Indo-Pacific humpback dolphins (Sousa chinensis) stranded in the Pearl River Estuary (PRE), China. The lowest blubber/tissue partition coefficients were found for sum hexachlorocyclohexanes (ΣHCHs) and ΣPAHs, while the highest were in ΣPCBs and sum dichlorodiphenyltrichloroethanes (ΣDDTs), likely attributing to the octanol-water partition features. The low levels of OCs in brain and testes theoretically resulted from the blood-brain barrier, blood-testes barrier, contaminant molecule dimensions and unique lipid compositions in the brain and testes. Compared with other contaminants, the higher mean brain/blood and testes/blood partition coefficients found for mirex, heptachlor, dieldrin and endrin would increase the risks associated with exposure-related toxicity and the bioavailability of contaminants within these tissues. Observations also suggest that as lipid mobilizes from blubber, contaminants may redistribute, leading to elevated tissue (such as brain) concentrations. Therefore, dolphins with less blubber may be more susceptible to health risks. The Indo-Pacific humpback dolphins living in PRE are at great risk due to variety of OCs in indirect contact with non-target organisms, affecting the health of animals (toxic effects and accumulation). Our findings contribute to the knowledge of the potential effects of OCs exposure on developmental neurotoxicity and reproductive damage in marine mammals.

Exposure to pyrethroid pesticides and ovarian reserve

INTRODUCTION

Synthetic pyretroids are among the most common pesticides currently used worldwide. Animal studies suggest that exposure to pyrethroids could dysregulated the function of the ovary, mainly follicular development and/or synthesis of the reproductive hormone. Nevertheless data regarding the effect of exposure on female ovarian function is limited. So the aim of the present study is to assess the effect of exposure to synthetic pyrethroids on ovarian reserve.

MATERIALS AND METHODS

The study population consists of 511 females aged 25-39 years attending infertility clinics for diagnostic purposes, because of couples' infertility. Validated gas chromatography ion-tap mass spectrometry method was used to assess the urinary concentrations of pyrethroid metabolites (CDDCA (cis-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid), TDDCA (trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid), 3PBA (3-phenoxybenzoic acid) and DBCA (cis-2,2-dibromovinyl-2,2-dimethylcyclopropane-1-carboxylic acid)). Ovarian reserve was assessed using parameters of ovarian reserve (antral follicle count and concentrations of hormones: AMH (anti-Mullerian hormone), FSH (follicle stimulating hormone) and E₂ (estradiol)).

RESULTS

In the present analysis the association was found between urinary concentrations of 3-PBA and levels of AMH (p = 0.03), FSH (p = 0.04) and antral follicle count (p = 0.02). Urinary level of CDCCA, TDCCA and DBCA was not associated with any examined parameters of ovarian reserve.

CONCLUSIONS

Synthetic pyrethroids may affect female ovarian reserve. As this is the first, preliminary study the results need confirmation in a further detailed investigations.

Effects and mechanisms of pyrethroids on male reproductive system

Synthetic pyrethroids are used as insecticides in agriculture and a variety of household applications worldwide. Pyrethroids are widely distributed in all environmental compartments and the general populations are exposed to pyrethroids through various routes. Pyrethroids have been identified as endocrine-disrupting chemicals (EDCs) which are responsible for the male reproductive impairments. The data confirm pyrethroids cause male reproductive damages. The insecticides exert the toxic effects on male reproductive system through various complex mechanisms including antagonizing androgen receptor (AR), inhibiting steroid synthesis, affecting the hypothalamic-pituitary-gonadal (HPG) axis, acting as estrogen receptor (ER) modulators and inducing oxidative stress. The mechanisms of male reproductive toxicity of pyrethroids involve multiple targets and pathways. The review will provide further insight into pyrethroid-induced male reproductive toxicity and mechanisms, which is crucial to preserve male reproductive health.

Cypermethrin exposure during perinatal period affects fetal development and impairs reproductive functions of F1 female rats

Cypermethrin (CYP) is a ubiquitously present synthetic pyrethroid insecticide. It has endocrine disrupting activities which may adversely affect reproductive development and functions of offspring if exposed during critical developmental period. The present study was undertaken to delineate the effects of CYP exposure in pregnant female rats during perinatal period on the sexual maturation, hormonal regulation, reproductive development and fertility of F1 female offspring and its molecular mechanism of action. Pregnant rats (F0) were gavaged daily with 0, 1, 10, 25 mg/kg bw/day CYP and 10 μg/kg bw/day Diethylstilbestrol (DES; positive control) from gestation day (GD) 6 to postnatal day (PND) 21. The reproductive development and function parameters were evaluated at PND 45 and 75. Reduced body weight, delayed vaginal opening, and disrupted estrous cyclicity were observed at 25 mg/kg CYP dose. CYP exposure significantly affected the reproductive organ development and their functions at all doses. Significant alterations in ovarian and uterine histology such as luteinization, reduction of primordial follicular reserves, presence of multi-oocyte follicles and thin degenerative luminal and glandular uterine epithelium were observed at adulthood. Altered circulatory steroid hormone levels and expression of ovarian and uterine steroid hormone receptors were observed at PND 75 in the F1 female offspring. Expression of HOXA10 and α-SMA which are important for uterine integrity and functions, were found to be altered at PND 75. Increased pre-implantation loss (PIL%), post-implantation loss (POL%), and reduced litter size in F1 females when cohabitated with unexposed fertile male rats were observed. Overall, perinatal exposure of pregnant rats to CYP led to significant long lasting effects on the reproductive functions of F1 female offspring. The adverse effects were passed on to F2 generation via female germ line and posed developmental anomalies. The present finding necessitates additional molecular studies to understand its trans-generational mechanism of action via female germline.

Flumethrin at sublethal concentrations induces stresses in adult honey bees (Apis mellifera L.)

Flumethrin is a typical pyrethroid varroacide widely used for mite control in beekeeping worldwide. Currently, information on the toxicological characteristics of flumethrin on bees at sublethal concentrations is still lacking. To fill this gap in information, we performed a 48-h acute oral and 14-day chronic toxicity testing of flumethrin in newly emerged adult honey bees under laboratory conditions. Results showed that flumethrin had high acute toxicity to honey bees with a 48-h LD₅₀ of 0.47 µg/bee (95% CI, 0.39 ∼ 0.57 µg/bee), which is higher than that of many other commercial pyrethroid insecticides, but lower than that of tau-fluvalinate. After 14 days of chronic exposure to flumethrin at 0.01, 0.10, and 1.0 mg/L, significant antioxidant response, detoxification, immune reaction, and apoptosis were observed in the midguts. These findings indicated that flumethrin had potential risks to bees, and it can disturb the homeostasis of bees at sublethal concentrations under longer exposure conditions. Flumethrin is highly lipophilic and easy to accumulate in beeswax; thus, careless practices might pose risks to colony development in commercial beekeeping and native populations. This laboratory study can serve as an early warning, and further studies are required to understand the real residual level of flumethrin in bees and the risks of flumethrin in field condition.

Bifenthrin Induces Fat Deposition by Improving Fatty Acid Uptake and Inhibiting Lipolysis in Mice

Chemical residues in the environment are considered to be important factors that cause obesity. Bifenthrin is one of the pyrethroid pesticides and is widely used worldwide. However, its effect on adipose tissue is ill-defined. Here, we administered bifenthrin/corn oil to adult C57BL/6 mice by gavage. After 6 weeks, the bifenthrin treatment significantly increased their body weight (P = 0.015) and fat mass (P < 0.001). Then we identified 246 differently expressed proteins by proteomic analysis, and they were highly involved in fatty acid uptake and lipid metabolism processes. Interestingly, protein hormone-sensitive lipase and adipose triacylglyceride lipase were downregulated while lipoprotein lipase is upregulated after bifenthrin treatment. Similar effects in 3T3-L1 cells treated with bifenthrin validated the in vivo results. Thus, this study suggests that long-term exposure to low-dose bifenthrin induces fat deposition in mice by improving fatty acid uptake and inhibiting lipolysis, and it may cause obesity in humans.

Assessment of the Insecticidal Potential of the Eupatorium buniifolium Essential Oil Against Triatoma infestans (Hemiptera: Reduviidae). A Chiral Recognition Approach

In this research, bioactivities toward the Chagas' disease vector Triatoma infestans (Klug) (Hemiptera: Reduviidae) by the essential oil (EO) of Eupatorium buniifolium H. et A. (Asteraceae) are reported. The tests were designed in order to determine ovicidal activity as well as the response to vapor exposure (fumigant) and to topical application (contact toxicity) and as repellent. In the last three bioassays, nymphs from the 3rd and 4th instar were used. The assayed materials were obtained from aerial parts of plants collected during the months of March and December, throughout 4 years, in two locations. The EO samples were subjected to a qualitative analysis by GC-MS and the relative area of each component was reported by GC-FID. The main monoterpene detected was α-pinene and by using a chiral column through GC-MS experiments and having both stereoisomers as standards, we were able to determine that the enantiomer present was S,S-(-)-α-pinene. Although usually in studies of EOs changes in chemical composition are often observed due to the time of collection and the environment where the plant develops, in our case the differences were, with some exception, only at the level of the minor components. The best results were obtained in the experiments to determine ovicidal activity, fumigant action, and repellency. No worthy response was found as insecticide in the trials designed for contact toxicity. The results of the studied bioactivities were independent of the location, month, and year of collection of the plant material. This behavior provides an interesting scope in relation to the potential use of this natural blend for the control of this insect at the nymph stage as repellent as well as for decreasing the population by ovicidal effect. Notably, in the course of the two-choice repellency test, it was possible to demonstrate recognition of one of the enantiomers of the α-pinene, giving rise to a non-common chirality/response effect. In this assay, the levorotatory isomer was the most active as repellent. Considering the abundance of the wild plant under study and the fact that its EO is easy to obtain, it is suggested that it could be an adequate natural resource to control this vector in a sustainable way as a complementary approach to conventional methods.

Screening cyhalothrin degradation strains from locust epiphytic bacteria and studying Paracoccus acridae SCU-M53 cyhalothrin degradation process

All locust epiphytic bacteria were screened and a total of 62 epiphytic bacteria were obtained from samples of Acrida cinerea. Via phylogenetic analysis, the 62 epiphytic bacteria were allocated to 27 genera, 18 families, 13 orders, six classes, and four phylums. Then, cyhalothrin degradation experiments were conducted, and the 10 strains that degraded more than 30% cyhalothrin and Paracoccus acridae SCU-M53 showed the highest cyhalothrin degradation rate of 70.5%. Furthermore, Paracoccus acridae SCU-M53 was selected for optimal cyhalothrin biodegradation conditions via the response surface method (Design-Expert). Under the optimum conditions (28 °C, 75 mg/L, and 180 rpm), the cyhalothrin degradation rate reached 79.84% after 2 days. This suggests the possibility that isolating biodegradation cyhalothrin strains from Acrida cinerea is feasible.