Steroidogenic alterations in testes and sera of rats exposed to formulated Fenvalerate by inhalation

Key proteins of proteome underlying sperm malformation of rats exposed to low fenvalerate doses are highly related to P53

Fenvalerate (Fen) is an endocrine disruptor, capable of interfering with the activity of estrogen and androgen. Our objective was to explore the molecular mechanisms of Fen on sperm in vivo. Adult male Sprague-Dawley rats were orally exposed to 0, 0.00625, 0.125, 2.5, 30 mg/kg/day Fen for 8 weeks. Sperm morphology, differential proteomics of sperm and testes, bioinformatic analysis, western blotting (WB), and RT-PCR were used to explore the mechanism of Fen on sperm. Data showed that low Fen doses significantly induced sperm malformations. In sperm proteomics, 47 differentially expressed (DE) proteins were enriched in biological processes (BPs) related to energy metabolism, response to estrogen, spermatogenesis; and enriched in cellular components (CCs) relating to energy-metabolism, sperm fibrous sheath and their outer dense fibers. In testicular proteomics, 56 DE proteins were highly associated with mRNA splicing, energy metabolism; and enriched in CCs relating to vesicles, myelin sheath, microtubules, mitochondria. WB showed that the expression of selected proteins was identical to their tendency in 2D gels. Literature indicates that key DE proteins in proteomic profiles (such as Trap1, Hnrnpa2b1, Hnrnpk, Hspa8, and Gapdh) are involved in P53-related processes or morphogenesis or spermatogenesis. Also, P53 mRNA and protein levels were significantly increased by Fen; bioinformatic re-analysis showed that 88.5% DE proteins and P53 formed a complex interacting network, and the key DE proteins were coenriched with P53-related BPs. Results indicate that key DE proteins of proteome underlying sperm malformations of rats exposed to low Fen doses are highly related to P53.

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.

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.

Pesticide residues in honey and their potential reproductive toxicity

Honey is the sweet natural substance produced by honeybees. It may be contaminated with pesticide residues due to its intensive use. Almost no reviews have addressed pesticide residues in honey, calculated a hazard index or discussed their potential reproductive toxicity. The focus of this article is primarily to summarize advances in research related to pesticide residues, estimate daily intake of pesticide residues from consuming honey only and discuss the potential reproductive toxicity associated with those residues. The results showed that 92 pesticide residues were found in honey samples from 27 countries. Six residues belong to class IA toxicity, eight residues belong to class IB toxicity, 42 residues belong to class II, 35 residues belong to class III and one residue belong to class IV toxicity. The calculated hazard indices (HIs) suggest high potential health risk by consuming honey. In addition, residues found in honey are known to impair semen quality among exposed individuals and experimental animal models. In conclusion, consumption of honey as one of many food items contaminated with pesticide residues may induce male and female reproductive toxicity in consumers.

An epigenome-wide association study of ambient pyrethroid pesticide exposures in California's central valley

BACKGROUND

Pyrethroid pesticide use is increasing worldwide, although the full extent of associated health effects is unknown. An epigenome-wide association study (EWAS) with exploratory pathway analysis may help identify potential pyrethroid-related health effects.

METHODS

We performed an exploratory EWAS of chronic ambient pyrethroid exposure using control participants' blood in the Parkinson's Environment and Genes Study in the Central Valley of California (N = 237). We estimated associations of living and working near agricultural pyrethroid pesticide applications in the past 5 years (binary) with site-specific differential methylation, and used a false discovery rate (FDR) cut off of 0.05 for significance. We controlled for age, sex, education, cell count, and an ancestral marker for Hispanic ethnicity. We normalized methylation values for Type I/II probe bias using Beta-Mixture Quantile (BMIQ) normalization, filtered out cross-reactive probes, and evaluated for remaining bias with Surrogate Variable Analysis (SVA). We also evaluated the effects of controlling for cell count and normalizing for Type I/II probe bias by comparing changes in effect estimates and p-values for the top hits across BMIQ and GenomeStudio normalization methods, and controlling for cell count. To facilitate broader interpretation, we annotated genes to the CpG sites and performed gene set overrepresentation analysis, using genes annotated to CpG sites that were associated with pyrethroids at a raw p < 0.05, and controlling for background representation of CpG sites on the chip. We did this for both a biological process context (Gene Ontology terms) using missMethyl, and a disease set context using WebGestalt. For these gene set overrepresentation analyses we also used an FDR cut off of 0.05 for significance of gene sets.

RESULTS

After controlling for cell count and applying BMIQ normalization, 4 CpG sites were differentially methylated in relation to pyrethroid exposures. When using GenomeStudio's Illumina normalization, 415 CpG sites were differentially methylated, including all four identified with the BMIQ method. In the gene set overrepresentation analyses, we identified 6 GO terms using BMIQ normalization, and 76 using Illumina normalization, including the 6 identified by BMIQ. For disease sets, we identified signals for Alzheimer's disease, leukemia and several other cancers, diabetes, birth defects, and other diseases, for both normalization methods. We identified minimal changes in effect estimates after controlling for cell count, and controlling for cell count generally weakened p-values. BMIQ normalization, however, resulted in different beta coefficients and weakened p-values.

CONCLUSIONS

Chronic ambient pyrethroid exposure is associated with differential methylation at CpG sites that annotate to a wide variety of disease states and biological mechanisms that align with prior research. However, this EWAS also implicates several novel diseases for future investigation, and highlights the relative importance of different background normalization methods in identifying associations.

Role of the gene Phlda1 in fenvalerate-induced apoptosis and testicular damage in Sprague-Dawley rats

Fenvalerate (FEN), a pyrethroid insecticide used worldwide, has been shown to produce a potentially adverse effect on male reproduction. However the mechanisms are not completely understood. Thus this study aimed to (1) determine whether cellular apoptosis was involved in FEN-induced testicular damage in rats, and (2) identify the potential mechanism involved in FEN-induced apoptosis in testes. Data demonstrated that FEN markedly decreased serum testosterone levels, increased the inner diameter of seminiferous tubules, decreased the layers of spermatogenic cells, disturbed spermatogenesis and increased the number of apoptotic cells. Further, bioinformatic analysis of gene microarray in rat testis tissue showed that FEN significantly altered the expressions of genes (Krt8, Mal, Cd24, Lcn2, Phlda1, Arg2) related to apoptotic related processes. The expression pattern of these 6 genes was upregulated in FEN-treated rat testicular tissue. qRT-PCR analysis demonstrated that Phlda1, a well-documented pro-apoptotic factor, was significantly elevated by FEN. The expression of PHLDA1 testicular protein was also elevated following FEN exposure. In conclusion, our results suggest that FEN exposure induced deleterious effects on rat testes associated with Phlda1-mediated apoptosis which may act as a molecular mechanism underlying FEN induced rat testicular damage.

Effects of pyrethroid insecticides on hypothalamic-pituitary-gonadal axis: A reproductive health perspective

Pyrethroids, a class of ubiquitous insecticides, have been recognized as endocrine-disrupting chemicals (EDCs). A lot of studies have implied the endocrine-disrupting effects of pyrethroids on the hypothalamic-pituitary-gonadal (HPG) axis. However, there are few review articles regarding the effects of pyrethroids on the HPG axis of mammal and human, especially new research progress made in this area. The present review sums up the effects of pyrethroids on the HPG axis-related reproductive outcomes, including epidemiological investigations based on human biomonitoring, animal studies and in vitro tests. Mechanisms have described that the endocrine-disrupting effects of pyrethroids on mammal can be mediated via the interaction with steroid receptors, the direct action on ion channels and signaling molecules. Finally, we summarize the current research gaps and suggest future directions in this topic.

Quizalofop-P-ethyl exposure increases estrogen axis activity in male and slightly decreases estrogen axis activity in female zebrafish (Danio rerio)

The herbicide Quizalofop-P-ethyl (QpE) exerts toxic effects in fish, but limited information is currently available on its effects on the endocrine system. In the current study, adult zebrafish (Danio rerio) were exposed to different concentrations (0, 2, 20, 200μg/L) of QpE for 30days. In males, QpE exposure significantly increased plasma estradiol (E2) and vitellogenin (VTG) levels, concomitant with up-regulation of hepatic esr1 and vtg gene expression. In females, plasma sex hormone levels and VTG concentrations were not altered significantly, but an increased expression of hepatic esr1 in addition to decreased expression of hepatic vtg, esr2a and esr2b was observed. Marked histological lesions were also observed in the gonads of both males and females. Moreover, QpE exposure significantly increased transcriptional profiles of some genes in the HPG axis and liver in males, while the majority of these genes were down-regulated in females. Docking studies showed QpE forming stable interactions with the ligand-binding domain (LBD) of zebrafish ESR1 and ESR2a, suggesting QpE may bind to estrogen receptors (ESRs). This study for the first time reveals QpE as an endocrine-disrupting chemical (EDC) disrupting the zebrafish endocrine system in a sex-specific manner, whereby it increases estrogen axis activity in males and slightly decreases estrogen axis activity in females, which may be accounted for by QpE regulating steroidogenesis and/or activating ESR(s).

Effects of label-dose permethrin administration in yearling beef cattle: I. Bull reproductive function and testicular histopathology

Pyrethroid administration to a wide variety of laboratory animals has been shown to cause detrimental effects on male fertility, including sperm quality, by means of endocrine disruption. The objective of this experiment was to study the effects of a commercial, permethrin-containing pour-on product on reproductive variables and testicular histopathology of yearling beef bulls. Black Angus bulls (n = 60; aged 369 ± 17 days; 511 ± 33 kg; 6.2 ± 0.5 body condition scores) were assigned to either (1) saline control (CON) or (2) permethrin pour-on administered at label dose (PYR). Blood samples were collected, and industry standard breeding soundness examinations (BSE), via electroejaculation, were performed on all bulls at 5 days before and 14 days after treatment. Progressive sperm motility and eosin-nigrosin-stained sperm were analyzed using high-power phase-contrast microscopy. Plasma testosterone concentrations were analyzed via radioimmunoassay. Bulls were slaughtered at 34 days, and one testicle per bull was randomly collected for histologic examination. Change in sperm motility between BSEs was not different because of treatment; sperm morphology however improved across treatments, but PYR bulls had less improvement in percent of head (P < 0.001) sperm abnormalities compared to CON, resulting in less improvement of primary abnormalities (P = 0.04). Nonetheless, morphological differences did not change the overall outcome for satisfactory breeder status. Change in testosterone concentration did not differ because of treatment. Histopathologic examination identified that testicular degeneration and tubule diameter did not differ as a result of treatment. It should be noted, however, that degeneration score (higher score having more degeneration) was positively correlated with primary abnormalities (P < 0.01; r = 0.35) and negatively correlated with normal sperm cells (P < 0.001; r = -0.43). In summary, these data indicate that a single use of permethrin at label dose in yearling Angus bulls results in minimal detrimental effects on sperm morphology but not to a degree that impacts the ability of bulls to pass a standard BSE.

A fluorescent molecularly imprinted polymer sensor synthesized by atom transfer radical precipitation polymerization for determination of ultra trace fenvalerate in the environment

In this study, novel fluorescence molecularly imprinted polymers (FMIPs) were prepared via atom transfer radical precipitation polymerization (ATRPP) for the optical detection of trace fenvalerate (FE).

Reproductive toxicity and histopathological changes induced by lambda-cyhalothrin in male mice

Lambda-cyhalothrin (LCT) is a widely used broad-spectrum pyrethroid insecticide. Oral LCT administration to adult male mice at 3 doses (0.2, 0.4, and 0.8 mg/kg/day) for 6 weeks caused a significant reduction in the weight of the seminal vesicles. The epididymal sperm count was lower in mice that received at the highest dose than in control mice. However, the proportions of live and motile spermatozoa were reduced at both the medium and the high doses compared with control mice. All doses induced an increase in the number of morphologically abnormal spermatozoa. Histopathological observations of the testes, liver, kidneys, and spleen showed dose-related degenerative damage in LCT-treated mice. The results indicate that LCT has reproductive toxicity, hepatotoxicity, nephrotoxicity, and splenotoxicity in male mice at the tested doses. © 2012 Wiley Periodicals, Inc. Environ Toxicol 29: 750-762, 2014.

Pyrethroid insecticide exposure and semen quality of young Japanese men

The present study aimed at assessing the relationship between exposure to pyrethroid insecticides and semen quality in 323 university students recruited in a population-based manner in Metropolitan Tokyo. Urinary concentrations of pyrethroid insecticide metabolite, 3-phenoxybenzoic acid (3-PBA), were measured by LC/MS/MS and semen parameters were measured by following internationally harmonized protocols. Median urinary 3-PBA concentration was 0.641 ng/mL (specific gravity-adjusted, n=322). Median values of semen volume, sperm concentration, motility, total number of sperm, and total number of motile sperm were 2.5 mL, 56×10(6)/mL, 61%, 141×10(6), and 82×10(6), respectively. Urinary concentration of 3-PBA was not selected as significant in multiple regression models indicating, in contrast to previous findings, that environmental exposure to pyrethroid insecticides did not affect semen quality. This inconsistency may be related to exposure to different pyrethroid insecticides and/or levels of exposure as well as to survey design (hospital- vs population-based subject recruitment).

Paternal fenvalerate exposure influences reproductive functions in the offspring

Fenvalerate (Fen), a synthetic pyrethroid insecticide, has been shown to have adverse effects on male reproductive system. Thus, the aim of the present study was to elucidate whether these adverse effects are passed from exposed male mice to their offspring. Adult male mice received Fen (10 mg/kg) daily for 30 days and mated with untreated females to produce offspring. Fenvalerate significantly changed the methylation status of angiotensin I-converting enzyme (Ace), forkhead box O3 (Foxo3a), huntingtin-associated protein 1 (Hap1), nuclear receptor subfamily 3 (Nr3c2), promyelocytic leukemia (Pml), and Prostaglandin F2 receptor negative regulator (Ptgfrn) genes in paternal mice sperm genomic DNA. Further, Fen significantly increased sperm abnormalities; serum testosterone and estradiol-17ß level in adult male (F0) and their male offspring (F1). Further, paternal Fen treatment significantly increased the length of estrous cycle, serum estradiol-17ß concentration in estrus, and progesterone levels in diestrus in female offspring (F1). These findings suggest that adverse effects of paternal Fen exposure on reproductive functions can be seen not only in treated males (F0) but also in their offsprings.

Risk assessment of the exposure of insecticide operators to fenvalerate during treatment in apple orchards

Dermal and inhalation exposure of the applicator to the insecticide fenavalerate in an apple orchard was measured for risk assessment during treatment. Emulsifiable concentrate (EC) and wettable powder (WP) formulations were sprayed using a speed sprayer (SS) or power sprayer (PS). Dermal patches, gloves, socks, and masks were used to monitor potential dermal exposure to fenavalerate, while personal air samplers with XAD-2 resins were used to monitor potential inhalation exposure. Validation of analytical methods was performed for the instruments' limit of detection, limit of quantitation, reproducibility, linearity of calibration curve, and recovery of fenvelerate from various exposure matrices. The results were encouraging and reasonable for an exposure study. Applicability of XAD-2 resin was evaluated with a trapping efficiency and breakthrough test. During mixing/loading, the amount of dermal exposure ranged from 262.8 μg (EC/SS) to 1652.6 μg (WP/PS) of fenvalerate, corresponding to ~0.0011-0.0066% of the total prepared quantity. In the case of WP, the amount of dermal exposure was 2032.3 μg (0.0081% of the total applied amount) for SS and 1087.9 μg (0.0145%) for PS after application. In the case of EC, the amount of dermal exposure was 3804.6 μg (0.0152%) for SS and 4055.0 μg (0.0541%) for PS after application. The primary body parts subject to exposure were thigh and upper arm for SS, and thigh and hand for PS. The amount of inhalation exposure with WP was 2.2 μg (8.65 × 10⁻⁶% of the total applied amount) for SS and 1.3 g (1.67 × 10⁻⁵%) for PS. The amount of inhalation exposure with EC was 2.5 μg (9.81 × 10⁻⁶%) for SS and 3.7 μg (4.97 × 10⁻⁵%) for PS. The absorbable quantity of exposure and margin of safety (MOS) were calculated for risk assessment. The MOS for all 4 cases was much greater than 1, indicating a low possibility of risk.

Farm residence and reproductive health among boys in rural South Africa

BACKGROUND

Few studies have investigated reproductive health effects of contemporary agricultural pesticides in boys.

OBJECTIVES

To determine the association between pesticide exposure and reproductive health of boys.

METHODS

We conducted a cross-sectional study in rural South Africa of boys living on and off farms. The study included a questionnaire (demographics, general and reproductive health, phyto-estrogen intake, residential history, pesticide exposures, exposures during pregnancy); and a physical examination that included sexual maturity development ratings; testicular volume; height, weight, body mass index; and sex hormone concentrations.

RESULTS

Among the 269 boys recruited into the study, 177 (65.8%) were categorized as farm (high pesticide exposures) and 98 (34.2%) as non-farm residents (lower pesticide exposures). Median ages of the two groups were 11.3 vs 12.0 years, respectively (p<0.05). After controlling for confounders that included socioeconomic status, farm boys were shorter (regression coefficient (RC)=-3.42 cm; 95% confidence interval (CI): -6.38 to -0.45 cm) and weighed less (RC=-2.26 kg; CI: -4.44 to -0.75 kg). The farm boys also had lower serum lutenizing hormone (RC=-0.28 IU/L; CI: -0.48 to -0.08 IU/L), but higher serum oestradiol (RC=8.07 pmol/L; CI: 2.34-13.81 pmol/L) and follicle stimulating hormone (RC=0.63 IU/L; CI: 0.19-1.08 U/L).

CONCLUSIONS

Our study provides evidence that farm residence is associated with adverse growth and reproductive health of pubertal boys which may be due to environmental exposures to hormonally active contemporary agricultural pesticides.

Urinary concentrations of pyrethroid metabolites in the convenience sample of an urban population of Northern Poland

Urinary concentrations of pyrethroid metabolites were measured in the first void urine samples collected from 132 healthy people living in the Gdańsk region of Northern Poland in 2010 and 2011. Four metabolites of synthetic pyrethroids: cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acids (cis-, trans-Cl2CA), cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (Br2CA) and 3-phenoxybenzoic acid (3-PBA) were simultaneously liquid-liquid extracted, derivatized with hexafluoroisopropanol and analyzed by a gas chromatography ion-trap mass spectrometry. All the analytes were detected and quantified in the samples with various frequency, 3-phenoxybenzoic being the most often (80%) and the others less frequently (7-11%). Distribution of 3-PBA concentrations followed log-normal model, the mean concentration of 3-phenoxybenzoic acid: 0.393 μg/L (0.327 μg/g creatinine) is similar to those of the other general populations in various regions of the world. Neither sex nor age were predictors of urinary 3-PBA. Our findings suggest wide exposure to pyrethroid insecticides in the Polish general population. There is a continuous need to further study the exposure to synthetic pyrethroids among the general population since there is a strong, increasing trend in their usage.

Protective role of caffeic acid on lambda cyhalothrin-induced changes in sperm characteristics and testicular oxidative damage in rats

The synthetic pyrethroids are expected to cause deleterious effects on most of the organs and especially on the male reproductive system. The current study was performed to assess the adverse effect of lambda cyhalothrin (LC) on reproductive organs and fertility in male rats and to evaluate the protective role of caffeic acid phenethyl ester (CAPE) in alleviating the detrimental effect of LC on male fertility. A total of 48 male rats were divided into 4 groups (12 rats each): control group received distilled water ad libitum and 1 ml of vehicle solution given intraperitoneally (i.p.); CAPE-treated group received a single i.p. dose of CAPE (10 μmol kg⁻¹ day⁻¹); LC-treated group received 668 ppm of LC through drinking water; and CAPE + LC-treated group received an i.p. injection of CAPE (10 μmol kg⁻¹ day⁻¹) 12 h before the LC administration. The experiment was conducted for 10 consecutive weeks. LC caused a significant increase in testicular malondialdehyde, catalase, superoxide dismutase, glutathione-S-transferase activities, and sperm abnormalities and a significant reduction in testicular glutathione concentration, sperm count, sperm motility, and a live sperm percentage. Conversely, treatment with CAPE improved the reduction in the sperm characteristics, LC-induced oxidative damage of testes and the testicular histopathological alterations. Results indicate that LC exerts significant harmful effects on the male reproductive system and that CAPE reduced the deleterious effects of LC on male fertility.

Systematic review of biomonitoring studies to determine the association between exposure to organophosphorus and pyrethroid insecticides and human health outcomes

For the appropriate protection of human health it is necessary to accurately estimate the health effects of human exposure to toxic compounds. In the present review, epidemiological studies on the health effects of human exposure to organophosphorus (OP) and pyrethroid (PYR) insecticides have been critically assessed. This review is focused on studies where the exposure assessment was based on quantification of specific biomarkers in urine or plasma. The 49 studies reviewed used different epidemiological approaches and analytical methods as well as different exposure assessment methodologies. With regard to OP pesticides, the studies reviewed suggested negative effects of prenatal exposure to these pesticides on neurodevelopment and male reproduction. Neurologic effects on adults, DNA damage and adverse birth outcomes were also associated with exposure to OP pesticides. With regard to exposure to PYR pesticides, there are currently few studies investigating the adverse health outcomes due to these pesticides. The effects studied in relation to PYR exposure were mainly male reproductive effects (sperm quality, sperm DNA damage and reproductive hormone disorders). Studies' findings provided evidence to support the hypothesis that PYR exposure is adversely associated with effects on the male reproductive system. The validity of these epidemiological studies is strongly enhanced by exposure assessment based on biomarker quantification. However, for valid and reliable results and conclusions, attention should also be focused on the validity of the analytical methods used, study designs and the measured toxicants characteristics.

Cloning and expression of the translocator protein (18 kDa), voltage-dependent anion channel, and diazepam binding inhibitor in the gonad of largemouth bass (Micropterus salmoides) across the reproductive cycle

Cholesterol transport across the mitochondrial membrane is rate-limiting for steroidogenesis in vertebrates. Previous studies in fish have characterized expression of the steroidogenic acute regulatory protein, however the function and regulation of other genes and proteins involved in piscine cholesterol transport have not been evaluated. In the current study, mRNA sequences of the 18 kDa translocator protein (tspo; formerly peripheral benzodiazepine receptor), voltage-dependent anion channel (vdac), and diazepam binding inhibitor (dbi; also acyl-CoA binding protein) were cloned from largemouth bass. Gonadal expression was examined across reproductive stages to determine if expression is correlated with changes in steroid levels and with indicators of reproductive maturation. In testis, transcript abundance of tspo and dbi increased with reproductive maturation (6- and 23-fold maximal increase, respectively) and expression of tspo and dbi was positively correlated with reproductive stage, gonadosomatic index (GSI), and circulating levels of testosterone. Testis vdac expression was positively correlated with reproductive stage and GSI. In females, gonadal tspo and vdac expression was negatively correlated with GSI and levels of plasma testosterone and 17β-estradiol. Ovarian dbi expression was not correlated with indicators of reproductive maturation. These studies represent the first investigation of the steroidogenic role of tspo, vdac, and dbi in fish. Findings suggest that cholesterol transport in largemouth bass testis, but not in ovary, may be transcriptionally-regulated, however further investigation will be necessary to fully elucidate the role of these genes in largemouth bass steroidogenesis.

Cypermethrin exposure during puberty induces oxidative stress and endocrine disruption in male mice

Cypermethrin (CYP) is one of the most common contaminants in the ecosystem. The effects of CYP exposure on the induction of oxidative stress and endocrine disruption were studied in adolescent male ICR mice. The hepatic activities of antioxidant enzymes including superoxide dismutase (SOD), glutathione peroxidase (GPX), catalase (CAT) and total antioxidant capacity (T-AOC) increased significantly after 3 weeks (postnatal day 21-42) of oral administration of 20 mg kg(-1) CYP. In accordance with the enzyme activities, the mRNA levels for the genes encoding these antioxidant proteins, such as Sod1, Sod2, Gpx1 and Gpx2, were also up-regulated significantly in the 10 and 20 mg kg(-1) CYP treatment groups. Furthermore, we also found that the 3-week oral administration of CYP decreased transcription levels of key genes in pathways of cholesterol synthesis and transport and testosterone synthesis including HMG-CoA synthase, steroidogenic acute regulatory protein (StAR) and cytochrome P450 17α-hydroxysteroid dehydrogenase (P450 17α in the liver and testes. Serum testosterone levels also decreased significantly in mice after treatment with 20 mg kg(-1) CYP. Taken together, the results indicated that CYP can induce endocrine disruption in adolescent mice. The findings will be helpful in elucidating the mechanism of toxicity induced by CYP in adolescent mice.

Pubertal and early adult exposure to fenvalerate disrupts steroidogenesis and spermatogenesis in mice at adulthood

Fenvalerate, a pyrethroid insecticide used worldwide, has been shown to have a potentially adverse effect on male reproduction. Our earlier study showed that maternal fenvalerate exposure during lactation impaired testicular development in male offspring. In this study, we investigated the effects of pubertal and early adult exposure to fenvalerate on steroidogenesis and spermatogenesis in mice. Male mice were administered fenvalerate (60 mg/kg) by gavage daily from postnatal day 35 (PND35) to PND63. Results showed that sperm count was significantly decreased in fenvalerate-treated mice. In addition, fenvalerate markedly decreased the layers of spermatogenic cells, disturbed the array of spermatogenic cells and increased the number of apoptotic cells in testes. The adverse effects of fenvalerate on male reproduction seemed to be associated with a decrease in serum and testicular testosterone (T). Although pubertal and early adult exposure to fenvalerate had little effect on the number of Leydig cells in testes, mRNA and protein levels of testicular T biosynthetic enzymes including P450(17alpha) and P450scc were significantly downregulated in fenvalerate-treated mice. In conclusion, pubertal and early adult fenvalerate exposure induces a deleterious effect on steroidogenesis and spermatogenesis in adulthood. The decreased testicular T synthesis partially contributes to fenvalerate-induced impairment on spermatogenesis.

Fenvalerate exposure alters thyroid hormone status in selenium- and/or iodine-deficient rats

Considering the potential adverse effects of selenium and iodine deficiencies, and taking into account the widespread but often careless use of pyrethroid insecticides and their possible endocrine-disrupting effects, this study was undertaken to investigate the effects of fenvalerate on thyroid hormone parameters in both healthy and selenium- and/or iodine-deficient rats. Fenvalerate exposure had no effect on the TT4 levels of healthy controls but caused significant increases both in iodine deficiency (ID) and selenium plus iodine deficiency (ISeD), and a significant decrease in selenium deficiency (SeD). Dramatic increases in TT3 of all groups were observed by fenvalerate. Moreover, it caused insignificant decrease of thyroid stimulating hormone in healthy controls, no effect in SeD, and significant elevation in ID and ISeD. These results, thus, showed that the widely used pyrethroid insecticide fenvalerate has the potential to change significantly thyroid hormone parameters both in normal and deficiency states, and consequences of its thyroid status modifying effect might be of critical importance particularly in sensitive individuals and patients with thyroid dysfunction.

Effects of dermal sub-chronic exposure of pubescent male rats to permethrin (PRMT) on the histological structures of genital tract, testosterone and lipoperoxidation

Short-term effects of pyrethroids on human health are better and well identified, whereas long-term risk's estimation remains difficult, especially those affecting the reproductive function. The present study, carried out in male rats, is a contribution to explore some effects underlying permethrin (PRMT) toxicity. The aim of the present work was to investigate the effect of different subcutaneous treatments with PRMT low doses on testes and epididymides histopathology, testosterone and oxidative stress in pubescent male rats. Groups of six animals were treated with a dermal daily dose of 0.013, 0.13, or 1.3 mg/kg b.w/day of PRMT in 70% ethanol for 30, 45, and 60 days, respectively. Macroscopic studies showed an influence of PRMT on the testes, the epididymides and body weight. The pyrethroid induces a testis disturbance traduced by a deregulation of spermatogenesis and an epididymis dysfunction by the appearance of strong deformations into the microstructure of the epididymides. A hormonal disruption was evidenced by the measurement of the plasma testosterone concentrations. The findings of the present investigation mentioned a significant increase (p≤0.05) in lipoperoxidation, after 45 or 60 days, when we measured the plasma malondialdehyde (MDA) concentrations. In conclusion the study shows that subcutaneous PRMT treatment causes an arrest of spermatogenesis, and a significant disharmony in testosterone concentration and MDA levels. These effects are related to dose, length of treatment and to the lipid peroxidation, which may be one of the molecular mechanisms involved in PRMT-induced gonads and epididymides toxicity.

Fenvalerate inhibits the growth of primary cultured rat preantral ovarian follicles

Fenvalerate is a widely used synthetic pyrethroid insecticide and is reported to disrupt reproductive function in humans and animals. However, little is known about its influence on follicular development. In this study, rat preantral follicles were primary cultured to investigate the effects of fenvalerate on follicular survival rate, morphological change, steroid hormone levels and steroidogenesis related gene mRNA expression. Follicles were cultured with 0, 1, 5 and 25 micromol/L fenvalerate for 72 h. And then the morphous was assessed by conventional light microscopy, steroid hormones were measured by RIA, and the expressions of steroidogenic acute regulatory protein (StAR) and cytochrome P450 side-chain cleavage enzyme (P450scc) were monitored by real-time quantitative PCR analysis. Results showed that fenvalerate inhibited the augmentation of follicular diameters but did not have detectable effects on follicular survival rates. The level of steroid hormones, such as progesterone, testosterone and estradiol, was inhibited. The inhibition might be due to the decreased expression levels of StAR and P450scc. These results suggested that fenvalerate restrained the follicular growth, and inhibited steroidogenesis by reducing StAR and P450scc gene expression, which might further contribute to the fenvalerate-induced reproductive dysfunction.

Decreased sperm motility in rats orally exposed to single or mixed pesticides

The Brazilian Agency of Sanitary Vigilance (ANVISA) conducted a study that demonstrated the presence of residues of several pesticides in fresh fruits and vegetables that were available for purchase by the general populace. In order to evaluate potential adverse health effects of low-level exposure to agrochemicals, the reproductive toxicity of the pesticides dicofol, dichlorvos, permethrin, endosulfan, and dieldrin was evaluated in rats dosed with these chemicals individually or as mixtures. Sixty male Lewis rats (6 wk old, 200 x g) were randomly allocated to 8 groups: (1) control group, received basal diet; (2) 5 groups designated a to e received the diet containing each pesticide individually, at the respective effective doses: lowest-observed-adverse-effect level (LOAEL) for dieldrin and endosulfan, lowest-observed-effect level (LOEL) for dicofol, and lowest effect level (LEL) for dichlorvos and permethrin, respectively, depending on the published data; (3) effective dose group, which received a mixture of pesticides added to basal diet at the respective doses reported to produce adverse effects; and (4) low dose group, which received a pesticide mixture added to the basal diet, where each pesticide was at its no-observed-effect level (NOEL). After 8 wk of treatment, reproductive parameters were evaluated. Sperm morphology, daily sperm production (DSP), sperm transit time through the epididymis, hormonal levels, and histopathological evaluation of testis and epididymis did not differ significantly among the groups. However, sperm motility was significantly decreased in animals that received a mixture of dieldrin, endosulfan, dicofol, dichlorvos, and permethrin, as well as in the group receiving dicofol alone. Exposure to the individual pesticides endosulfan, dichlorvos, and permethrin did not markedly affect sperm motility. The impairment of sperm motility in the mixture of pesticides at the NOEL level indicates that reproductive effects not seen with individual pesticides may occur in presence of several pesticides due to an additive effect. However, the pesticide mixtures did not appear to affect DSP or spermatogenesis despite reduced sperm motility.

Effects of gestational and lactational fenvalerate exposure on immune and reproductive systems of male rats

The aim of this study was to determine the consequent reproductive developmental and immunotoxic effects due to exposure to fenvalerate during pregnancy and lactation in male offspring of maternal-treated rats. Pregnant rats were treated daily by oral gavage with 40 or 80 mg/kg of fenvalerate or corn oil (vehicle, control), from d 12 of pregnancy to d 21 of lactation. Immune and reproductive developmental effects were assessed in male offspring at postnatal days (PND) 40 (peripuberty), 60 (postpuberty), and 90 (sexual maturity). Treatment with the higher dose (80 mg/kg) resulted in convulsive behavior, hyperexcitability, and mortality in 45% of the dams. Fenvalerate was detected in the fetus due to placental transfer, as well as in pups due to breast-milk ingestion, persisting in male offspring until PND 40 even though pesticide treatment was terminated on PND 20. However, fenvalerate did not produce marked alterations in age of testicular descent to the scrotum and prepucial separation, parameters indicative of puberty initiation. In contrast, at puberty, there was a reduction in testicular weight and sperm production in male offspring of maternal-treated rats. At adulthood, the sperm counts and fertility did not differ between control and treated groups. Testosterone levels were not changed at any time during reproductive development. Similarly, no apparent exposure-related effects were detected in the histological structures of the lymphohematopoietic system. Data indicate that fenvalerate, in this experimental model, interfered with initial development of the male reproductive system, but that these effects on sperm production or fertility did not persist into adulthood. There was no apparent evidence that fenvalerate altered testosterone levels or produced a disruption in male endocrine functions.

Pyrethroid insecticide metabolites are associated with serum hormone levels in adult men

Experimental studies have reported that pyrethroid insecticides affect male endocrine and reproductive function, but human data are limited. We recruited 161 men from an infertility clinic between years 2000-2003 and measured serum reproductive and thyroid hormone levels, as well as the pyrethroid metabolites 3-phenoxybenzoic acid (3PBA) and cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (cis-DCCA and trans-DCCA) in spot urine samples. When adjusting for potential confounders, categories for all three metabolites, as well as their summed values, were positively associated with FSH (all p-values for trend <0.05). Statistically significant or suggestive positive relationships with LH were also found. In addition, cis-DCCA and trans-DCCA were inversely associated with inhibin B (p for trend=0.03 and 0.02, respectively). Finally, there was evidence that trans-DCCA was inversely associated with testosterone and free androgen index (the ratio of testosterone to sex hormone binding globulin; p for trend=0.09 and 0.05, respectively). The observed relationships were consistent with previous findings, but further research is needed for a better understanding of the potential association between pyrethroid insecticides and male reproduction.

Human semen quality and sperm DNA damage in relation to urinary metabolites of pyrethroid insecticides

BACKGROUND

Exposure to synthetic pyrethroid insecticides is widespread, and is expected to increase among the general population due to the need to replace other common insecticides following regulatory use restrictions. On the basis of limited studies, there is animal and human evidence for altered reproductive or endocrine function following pyrethroid exposure.

METHODS

The present study measured urinary pyrethroid metabolites [3-phenoxybenzoic acid (3PBA) and cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (CDCCA and TDCCA)], semen quality, sperm motion parameters and sperm DNA damage with the neutral comet assay in 207 men recruited from an infertility clinic.

RESULTS

In multivariate analysis, the highest 3PBA quartile was associated with a suggestive 20.2 million sperm/ml reduction (95% confidence interval -37.1 to + 2.6) in sperm concentration compared with men below the 3PBA median. There were significant inverse associations between TDCCA and sperm motility and sperm motion parameters when adjusting for CDCCA and other covariates. The highest TDCCA quartile was associated with a 15.5% decline (95% confidence interval -26.2 to -4.8) in sperm motility compared with men below the median. In multiple logistic analyses, there were dose-dependent increased odds for below reference sperm concentration, motility and morphology in relation to TDCCA. Among the comet assay measures, 3PBA and CDCCA were associated with increased sperm DNA damage, measured as percent DNA in the comet tail.

CONCLUSIONS

We found evidence for reduced semen quality and increased sperm DNA damage in relation to urinary metabolites of pyrethroid insecticides. These findings may be of concern due to increased pyrethroid use and prevalent human exposure.

The relationship of 3-PBA pyrethroids metabolite and male reproductive hormones among non-occupational exposure males

Many pesticides possess hormonal activities and have been classified as endocrine disrupting chemicals. Synthetic pyrethroids are one kind of the most common pesticides used in the world. In the present study, we explored the association between serum reproductive hormone levels and urinary creatine (CR) adjusted concentration of 3-phenoxybenzoic acid (3-PBA), a general metabolite of pyrethroids, in Chinese adult men. The study subjects (n=212) were from the affiliated hospitals of Nanjing Medical University. By using GC-MS, urinary 3-PBA level of each subject was measured and adjusted by urinary CR. Blood samples were collected for measuring the serum levels of reproductive hormones, including follicle stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2), testosterone (T) and prolactin (PRL). All the subjects had detectable levels of 3-PBA in their urine samples. The median concentration of 3-PBA was 0.815 microg g (-1)of CR. The results showed that there was positive associations between the levels of serum LH and 3-PBA (p=0.013) but negative associations between E2 and 3-PBA level (p=0.022), and the adjusting p-value was 0.044 for LH and E2, which suggested that pyrethroids are capable of disrupting the male endocrine function. In adult men, urinary 3-PBA levels were associated with increased LH and reduced E2 levels. On a population level, these reductions show potential public health importance because of widespread exposure to these pesticides.

The relation between urinary metabolite of pyrethroid insecticides and semen quality in humans

OBJECTIVE

To explore the possible association between internal exposure levels of 3-phenoxybenzoic acid (3-PBA), an urinary metabolite of pyrethroids, and altered semen quality in Chinese men.

DESIGN

A retrospective case-control study.

SETTING

Center of clinical reproductive medicine.

PATIENT(S)

Three hundred seventy-six men with nonobstructive infertility.

MAIN OUTCOME MEASURE(S)

Urinary 3-PBA concentration, semen volume, sperm concentration, sperm number per ejaculum, sperm motility, sperm progression, and motion parameters.

RESULT(S)

The median 3-PBA concentration was 0.879 microg/g of creatinine. There was suggestive association between increased creatinine-adjusted 3-PBA quartiles and sperm concentration (odd ratios for the first, second, third, and fourth quartiles were 1.00, 1.31, 1.73, and 2.04, respectively), whereas sperm volume, sperm number per ejaculum, and sperm motility were weakly or nonsignificantly associated with 3-PBA quartiles. The sperm progression and motion parameters associated with creatinine-adjusted 3-PBA levels were straight line velocity (VSL) and curvilinear velocity (VCL).

CONCLUSION(S)

These observed associations between 3-PBA levels and some altered semen quality indicated the reproductive effects of pyrethroid exposure on adult men.

Human exposure to endocrine disrupters and semen quality

Reproductive pathology in the male represents about 20% of infertility cases. Male infertility may be attributed to a number of causes, including genetic and congenital abnormalities, infection, multisystemic diseases, varicocele, and others; however, a significant number of cases are idiopathic. Global declines in semen quality were suggested to be associated with enhanced exposure to environmental chemicals that act as endocrine disrupters as a result of our increased use of pesticides, plastics, and other anthropogenic materials. A significant body of toxicology data based upon laboratory and wildlife animals studies suggests that exposure to certain endocrine disrupters is associated with reproductive toxicity, including (1) abnormalities of the male reproductive tract (cryptorchidism, hypospadias), (2) reduced semen quality, and (3) impaired fertility in the adult. There is, however, a relative paucity of studies designed to measure exposure to endocrine disrupters on semen quality parameters (sperm concentration, motility, morphology). An overview of the human semen quality literature is presented that examines the role of endocrine disrupters including organochlorines (OC), dioxins, phthalates, phytoestrogens, and chemical mixtures (pesticides and tobacco smoke).

Fenvalerate, a pyrethroid insecticide, adversely affects sperm production and storage in male rats

The aim of this study was to investigate the potential estrogenic activity of fenvalerate by examining reproductive and fertility capabilities in Wistar rats. Adult male animals were treated for 30 d with 20 or 40 mg/kg/d fenvalerate or corn oil (vehicle) by oral gavage. Further, a possible estrogenic activity of fenvalerate (0.4, 1, 4, 8, or 40 mg/kg) was tested after a 3-d treatment of immature female rats using the uterotrophic assay. Exposure to the higher dose of fenvalerate was toxic to testis and epididymis as shown by a decrease in the absolute weights and sperm counts in both organs. Although the sperm counts were reduced, the fertility and sexual behavior were similar in control rats and rats treated with 40 mg/kg pesticide. Fenvalerate did not exert estrogenic activity in vivo at the tested doses. Data suggest that fenvalerate treatment in this study failed to compromise fertility, possibly due to enhanced reproductive capacity in rodents compared to humans.

Effects of fenvalerate and cypermethrin on rat sperm motility patterns in vitro as measured by computer-assisted sperm analysis

Fenvalerate and cypermethrin were reported to impair male reproductive function, inducing significant reductions in epididymal sperm count. Further, fenvalerate was shown to reduce sperm motility. However, it is not clear whether fenvalerate and cypermethrin might impact sperm motility directly or indirectly by affecting spermatogenesis via interaction with androgens or their receptors. In this study, sperm suspensions were treated with fenvalerate and cypermethrin, respectively, at various concentrations (0, 1, 4, 16, or 64 micromol/L) for various times (1, 2, or 4 h). The motility parameters of sperm treated with these two insecticides were analyzed with a computer-assisted sperm analysis (CASA) system. The differential effects of fenvalerate and cypermethrin on rat sperm motility patterns in vitro were also compared. Our study revealed that fenvalerate and cypermethrin reduced sperm motility in vitro in a concentration- and time-dependent manner. Cypermethrin exerted a greater effect on sperm motility in comparison to fenvalerate. These results provided evidence that fenvalerate and cypermethrin directly influence mature rat sperm motility.

Fenvalerate inhibits progesterone production through cAMP-dependent signal pathway

Fenvalerate is a widely used synthetic pyrethroid insecticide and is known to impede the male reproductive function. However, the mechanisms remain to be elucidated. In this study, mouse Leydig tumor cells (MLTC-1) were used to investigate the effects of fenvalerate on progesterone production. Fenvalerate treatment inhibited progesterone secretion induced by human chorionic gonadotropin (hCG), cholera toxin (CT) or forskolin and decreased cAMP levels induced by hCG, but not by CT or forskolin, which suggested a repaired site on the upstream components of G protein or G protein per se by fenvalerate in the cAMP-mediated signal pathway. Furthermore, the addition of cAMP analog, 8-Br-cAMP, could not reverse fenvalerate-suppressed progesterone synthesis, indicating that fenvalerate interfered with the downstream molecules of cAMP. In addition, fenvalerate decreased steroidogenic acute regulatory protein (StAR) mRNA and protein levels, and also profoundly inhibited the activity of P450 side chain cleavage enzyme (P450scc) which was consistent with the decreased expression of P450scc mRNA and protein in MLTC-1 cells. These results suggested that fenvalerate might inhibit progesterone production by attenuating cAMP generation and inhibiting StAR expression and P450scc activity.