Upregulation of peripubertal rat Leydig cell steroidogenesis following 24 h in vitro and in vivo exposure to atrazine

Endocrine toxicity of atrazine and its underlying mechanisms

Atrazine (ATR) is one of the most widely utilized herbicides globally and is prevalent in the environment due to its extensive use and long half-life. It can infiltrate the human body through drinking water, ingestion, and dermal contact, and has been recognized as an environmental endocrine disruptor. This study aims to comprehensively outline the detrimental impacts of ATR on the endocrine system. Previous research indicates that ATR is harmful to various bodily systems, including the reproductive system, nervous system, adrenal glands, and thyroi d gland. The toxic effects of ATR on the endocrine system and its underlying molecular mechanisms are summarized as follows: influencing the expression of kisspeptin in the HPG axis, consequently affecting steroid synthesis; disrupting DNA synthesis and meiosis, as well as modifying DNA methylation levels, leading to reproductive and developmental toxicity; impacting dopamine by altering Nurr1, VMAT2, and DAT expression, consequently affecting dopamine synthesis and transporter expression, and influencing other neurotransmitters, resulting in neurotoxicity; and changing adipose tissue synthesis and metabolism by reducing basal metabolism, impairing cellular oxidative phosphorylation, and inducing insulin resistance. Additionally, a compilation of natural products used to mitigate the toxic effects of ATR has been provided, encompassing melatonin, curcumin, quercetin, lycopene, flavonoids, vitamin C, vitamin E, and other natural remedies. It is important to note that existing research predominantly relies on in vitro and ex vivo experiments, with limited population-based empirical evidence available.

Exposure to atrazine stimulates progesterone secretion and induces oxidative stress, inflammation, and apoptosis in the ovary of pseudopregnant rats

Atrazine (ATR) is one of the most commonly used herbicides worldwide. As an endocrine disruptor, it causes ovarian dysfunction, but the mechanism is unclear. We hypothesized that ATR could affect ovarian steroidogenesis, oxidative stress, inflammation, and apoptosis. In the current study, rats aged 28 days were treated with PMSG and HCG to obtain amounts of corpora lutea. Then, rats were injected with ATR (50 mg/kg/day) or saline (0.9%) for 7 days. Sera were collected to detect biochemical indices and progesterone (P4) level, ovaries were collected for antioxidant status, HE, qPCR, and WB analysis. Results showed that ATR exposure affected growth performance as well as serum TP, GLB, and ALB levels, increased serum P4 level and ovarian mRNA and protein levels of StAR, CYP11A1, and HSD3B. ATR treatment increased ovarian mRNA and protein levels of CREB but not PKA expression. ATR treatment increased ovarian mRNA abundances of Nrf-2 and Nqo1, MDA level, and decreased SOD, GST, and T-AOC levels. ATR exposure increased the mRNA abundances of pro-inflammatory cytokines including Tnf-α, Il-1β, Il-6, Il-18, and Inos. ATR exposure increased the mRNA and protein level of Caspase 3 and the ratio of BAX/BCL-2. In conclusion, NRF-2/NQO1 signaling pathway and CREB might be involved in the regulation of ATR in luteal steroidogenesis, oxidative stress, inflammation, and apoptosis in rat ovary.

The ROS/SIRT1/STAR axis as a target for melatonin ameliorating atrazine-induced mitochondrial dysfunction and steroid disorders in granulosa cells

The granulosa cells (GCs) of birds are essential for the reproduction and maintenance of populations in nature. Atrazine (ATR) is a potent endocrine disruptor that can interfere with reproductive function in females and Diaminochlorotriazine (DACT) is the primary metabolite of ATR in the organism. Melatonin (MT) is an endogenous hormone with antioxidant properties that plays a crucial role in development of animal germ cells. However, how ATR causes mitochondrial dysfunction, abnormal secretion of steroid hormones, and whether MT prevents ATR-induced female reproductive toxicity remains unclear. Thus, the purpose of this study is to investigate the protective effect of MT against ATR-induced female reproduction. In the present study, the GCs of quail were divided into 6 groups, as follows: C (Serum-free medium), MT (10 µM MT), A250 (250 µM ATR), MA250 (10 µM MT+250 µM ATR), D200 (200 µM DACT) and MD200 (10 µM MT+200 µM DACT), and were cultured for 24 h. The results revealed that ATR prevented GCs proliferation and decreased cell differentiation. ATR caused oxidative damage and mitochondrial dysfunction, leading to disruption of steroid synthesis, which posed a severe risk to GC's function. However, MT supplements reversed these changes. Mechanistically, our study exhibited that the ROS/SIRT1/STAR axis as a target for MT to ameliorate ATR-induced mitochondrial dysfunction and steroid disorders in GCs, which provides new insights into the role of MT in ATR-induced reproductive capacity and species conservation in birds.

Atrazine: cytotoxicity, oxidative stress, apoptosis, testicular effects and chemopreventive Interventions

Atrazine (ATZ) is an environmental pollutant that interferes with several aspects of mammalian cellular processes including germ cell development, immunological, reproductive and neurological functions. At the level of human exposure, ATZ reduces sperm count and contribute to infertility in men. ATZ also induces morphological changes similar to apoptosis and initiates mitochondria-dependent cell death in several experimental models. When in vitro experimental models are exposed to ATZ, they are faced with increased levels of reactive oxygen species (ROS), cytotoxicity and decreased growth rate at dosages that may vary with cell types. This results in differing cytotoxic responses that are influenced by the nature of target cells, assay types and concentrations of ATZ. However, oxidative stress could play salient role in the observed cellular and genetic toxicity and apoptosis-like effects which could be abrogated by antioxidant vitamins and flavonoids, including vitamin E, quercetin, kolaviron, myricetin and bioactive extractives with antioxidant effects. This review focuses on the differential responses of cell types to ATZ toxicity, testicular effects of ATZ in both in vitro and in vivo models and chemopreventive strategies, so as to highlight the current state of the art on the toxicological outcomes of ATZ exposure in several experimental model systems.

High doses of GrassOut Max poses reproductive hazard by affecting male reproductive function and early embryogenesis in Swiss albino mice

Clethodim is a widely used and approved class II herbicide, with little information about its impact on the reproductive system. Herein, we investigated the male reproductive toxicity of clethodim using a mouse model. GrassOut Max (26% clethodim-equivalent) or 50 mg kg^-1 body weight analytical grade clethodim (≥90%) were given orally to male mice for 10 d in varying doses. All parameters were assessed at 35 d from the first day of treatment. Significant decrease in testicular weight, decreased germ cell population, elevated DNA damage in testicular cells and lower serum testosterone level was observed post clethodim-equivalent exposure. Epididymal spermatozoa were characterized with significant decrease in motility, elevated DNA damage, abnormal morphology, chromatin immaturity and, decreased acetylated-lysine of sperm proteins. In the testicular cells of clethodim-equivalent treated mice, the expression of Erβ and Gper was significantly higher. Proteomic analysis revealed lower metabolic activity, poor sperm-oocyte binding potential and defective mitochondrial electron transport in spermatozoa of clethodim-equivalent treated mice. Further, fertilizing ability of spermatozoa was compromised and resulted in defective preimplantation embryo development. Together, our data suggest that clethodim exposure risks male reproductive function and early embryogenesis in Swiss albino mice via endocrine disrupting function.

Mitigating effect of L-carnitine against atrazine-induced hepatotoxicity: histopathological and biochemical analyses in albino rats

Atrazine (ATR) is an extensively used herbicide that is often found in drinking water and waterways. After metabolization and excretion in the liver, ATR residues or its metabolites were found in tissues causing harmful effects mainly to the endocrine system and liver. This study aimed to elucidate the toxic impact of ATR on the liver and possible ameliorative effects of L-carnitine (LC). It utilized 30 adult male albino rats divided into three equal groups; the control group received 0.5 cc distilled water orally for 14 days, an ATR-treated group received ATR in a dose of 400 mg/kg BW dissolved in distilled water by oral gavage daily for 14 days, and a protected group (ATR + LC) received 400 mg/kg BW of ATR dissolved in distilled water, plus 100 mg/kg LC dissolved in distilled water by oral gavage daily for 14 days. At the end of the experiment, the liver tissue was prepared for histological and biochemical analyses and showed significant elevation of liver enzymes and oxidative parameters, altered expression of apoptotic and antiapoptotic genes, and hepatic degenerative changes in the ATR-treated group. In conclusion, atrazine induces oxidative stress, inflammation, and apoptosis in the liver of rats, and these toxic effects can be alleviated by L-carnitine.

Curcumin improves the protective effects of quercetin against atrazine-induced testicular injury in adult Wistar rats

This study evaluated the beneficial protective effect of cotreatment of curcumin (CUR) and quercetin (QUE) on atrazine (ATZ)-induced testicular toxicity in rats. ATZ challenge diminished luteinizing hormone, follicular stimulating hormone, testosterone and myeloperoxidase enzyme activity, but these effects were attenuated on co-treatment with CUR and QUE. Also, co-treatment of CUR + QUE was better than separate administration of QUE at diminishing malondialdehyde and glutathione and improving tumour necrosis factor-α concentration, germ cell numbers (spermatogonia, spermatocytes and round spermatids) and epididymal sperm quality. Histologically, smaller sized tubules with degenerated epithelia and few germ cells were seen in the seminiferous tubules of the ATZ group whereas CUR + QUE pretreatment improved the histo-morphologic features of the tubules compared to the ATZ group and was also better than separate administration of QUE. We conclude that CUR can improve the protective effects of QUE against ATZ-induced testicular injury by enhancing the levels of reproductive hormones, recovering testicular biochemical parameters and improving the histological features of the testes.

Exposure to Atrazine through gestation and lactation period led to impaired sexual maturation and subfertility in F1 male rats with congenital deformities in F2 progeny

Several scientific reports suggest perturbed reproductive and developmental defects associated with environmental exposure to Atrazine (ATR). ATR has been associated with altered endocrine and reproductive functioning in-vivo exposed during the critical window of development. Thus, the present study investigates the effect of ATR exposure on F1-F2 male progeny exposed through gestation and lactation. F0 dams administered with ATR at doses 2, 10, 70, and 100 mg/kg b. wt/day from gestation day 6 to postnatal day 21. The F1 male rats were monitored for sexual maturation and subjected to fertility assessment on PND75. Delayed testicular descent was observed in 10, 70, and 100 mg/kg b. wt/day ATR dose with significantly lower serum testosterone, sperm count, and motility with testicular defects in F1 male. Expression of Androgen receptor (AR), Estrogen receptors (ER α and ER β), StAR, Aromatase, and INSL-3 were upregulated at all doses indicating estrogenic/anti-androgenic activity of ATR. Fertility assessment revealed subfertility in F1 males with high (%) pre- and post-implantation loss at 10, 70, and 100 mg/kg b. wt/day dose as compared to control. Further, F2 fetuses exhibited congenital disabilities viz. decreased weight, crown-rump length, and anogenital distance with several other morphological deformities. To conclude, ATR exerted estrogenic and/or anti-androgenic activity with fetotoxic effects through the male germline.

Atrazine impairs testicular function in BalB/c mice by affecting Leydig cells

Several studies have reported the effects of atrazine on the gonads of many experimental models. However, the short-term effects of in vivo exposure to atrazine on the testes of mice are not well clarified. Here we reported that adult BalB/c mice exposed to atrazine (50 mg kg^-1 body weight) by gavage for three consecutive days have reduced numbers of 3β-hydroxysteroid dehydrogenase positive Leydig cells (LCs), associated with increased in situ cell death fluorescence and caspase-3 immuno-expression in the testes. Consequently, immunostaining for cell cycle gene regulators showed increased expressions of p45, accompanied with increased expressions of cyclin D2 and E2. Histological observations of the gonads showed reduced number of germ cells in particular areas, sloughed seminiferous epithelium, presence of giant apoptotic cells close to the seminiferous tubule lumen and in the epididymal lumen along with low numbers of Leydig cells in the testicular interstitial areas. Similarly, LCs isolated from the testes of BalB/c mice that were exposed to atrazine (0.5, 25, 50 mg kg^-1 body weight) in the same manner as in the first experiment presented dose-dependent increased caspase-3 activity, decreased cell viability, intratesticular and serum testosterone concentrations and LCs testosterone secretion. In summary, atrazine appears to directly decrease the number of testosterone secreting LCs in mice through apoptosis.

Changes induced by atrazine in Clarias gariepinus provide insight into alterations in ovarian histoarchitecture and direct effects on oogenesis

Clarias gariepinus juveniles were exposed to environmentally relevant concentrations of 0 (control), 2.5, 25, 250 and 500 μg L^-1 atrazine in a quality-controlled 28-day laboratory procedure. Findings revealed a significant decrease in the levels of follicle-stimulating hormone, luteinizing hormone and prolactin relative to control (p < 0.05). Atrazine reduced the levels of testosterone while increasing the concentration of progesterone. Histologically, the control and treatments presented three stages of oocyte maturation: the chromatin nucleolar oocyte stage, early perinucleolar oocyte stage and the vitellogenic oocyte stage. However, in the ovaries of the treatment group with the lowest treatment concentration (2.5 μg L^-1), atretic oocytes with broken membranes invaded many of the dead ova and empty spaces. In other treatments (25, 250 and 500 μg L^-1), interfollicular spaces, vacuolation in oocyte formation, and dissolution of oocyte walls were observed. Disruption of the yolk vesicle and clumping of the cytoplasm in maturing oocytes was observed only at the highest atrazine concentration (500 μg L^-1). Gross alterations in ovarian histoarchitecture and reproductive hormone levels observed in this study showed interference with oogenesis which may result in reduced egg viability and fecundity in fish with ecological implications in water bodies exposed to atrazine even at reduced concentrations.

Environmental Impact on Male (In)Fertility via Epigenetic Route

In the last 40 years, male reproductive health-which is very sensitive to both environmental exposure and metabolic status-has deteriorated and the poor sperm quality observed has been suggested to affect offspring development and its health in adult life. In this scenario, evidence now suggests that epigenetics shapes endocrine functions, linking genetics and environment. During fertilization, spermatozoa share with the oocyte their epigenome, along with their haploid genome, in order to orchestrate embryo development. The epigenetic signature of spermatozoa is the result of a dynamic modulation of the epigenetic marks occurring, firstly, in the testis-during germ cell progression-then, along the epididymis, where spermatozoa still receive molecules, conveyed by epididymosomes. Paternal lifestyle, including nutrition and exposure to hazardous substances, alters the phenotype of the next generations, through the remodeling of a sperm epigenetic blueprint that dynamically reacts to a wide range of environmental and lifestyle stressors. With that in mind, this review will summarize and discuss insights into germline epigenetic plasticity caused by environmental stimuli and diet and how spermatozoa may be carriers of induced epimutations across generations through a mechanism known as paternal transgenerational epigenetic inheritance.

Atrazine exposure in gestation and breastfeeding affects Calomys laucha sperm cells

The present study evaluated the effects of low doses of atrazine administered during gestation and breastfeeding on sperm characteristics of the wild rodent Calomys laucha. Adult females were divided into groups of 10 and administered different doses of atrazine through gavage, during gestational or breastfeeding period. At 3 months of age, the F1 adult male progeny of these females was evaluated. We observed a drastic reduction in the total and progressive motility of male sperm cells at all doses and during both the exposure periods. Moreover, the plasma membrane integrity of adult male sperm cells decreased at all doses of atrazine administered during the breastfeeding, whereas the membrane fluidity of these cells increased at all tested doses. Atrazine led to a decrease in the sperm mitochondrial functionality at all doses and during both exposure periods. The damage to the sperm DNA was higher in males exposed to the highest dose (1.0 mg/kg) during the gestation period, and in animals exposed to the lowest dose of atrazine (0.1 mg/kg) during breastfeeding period. Furthermore, the highest dose (1.0 mg/kg) of atrazine reduced the sperm concentration. Furthermore, the reduced levels of reactive oxygen species (ROS) were observed at all evaluated doses in males exposed during the gestation period. These results suggest that the administration of low doses of atrazine at critical periods of development may permanently reduce the sperm quality in C. laucha.

Effects of short-time exposure to atrazine on miRNA expression profiles in the gonad of common carp (Cyprinus carpio)

BACKGROUND

Atrazine is widely used in agriculture and is a known endocrine disrupting chemical. Atrazine can seep into the water body through surface, posing a potential threat to the aquatic ecological environment and human drinking water source. In vertebrate, studies have shown that it can affect reproduction and development seriously, but its molecular mechanism for aquatic animals is unknown. Aquaculture is very common in China, especially common carp, whose females grow faster than males. However, the effects of atrazine on the reproduction of carp, especially miRNA, have not been investigated.

RESULTS

In this study, common carp (Cyprinus carpio) at two key developmental stages were exposed to atrazine in vitro. Sex ratio was observed to analyze the effect of atrazine on the sex. MiRNA expression profiles were analysed to identify miRNAs related to gonad development and to reveal the atrazine mechanisms interfering with gonad differentiation. The results showed that the sex ratio was biased towards females. Atrazine exposure caused significant alteration of multiple miRNAs. Predicted targets of differently-expressed miRNAs were involved in many reproductive biology signalling pathways.

CONCLUSIONS

Our results indicate that atrazine promoted the expression of female-biased genes by decreasing miRNAs in primordial gonad. In addition, our results indicate that atrazine can up-regulate aromatase expression through miRNAs, which supports the hypothesis that atrazine has endocrine-disrupting activity by altering the gene expression profile of the Hypothalamus-Pituitary-Gonad axis through its corresponding miRNAs.

T-2 toxin downregulates LHCGR expression, steroidogenesis, and cAMP level in human cumulus granulosa cells

Our goals were to investigate whether environmentally relevant doses of T-2 toxin can affect human ovarian granulosa cells' function and to reveal the potential mechanism of T-2 toxin's action. Results showed that T-2 toxin strongly attenuated luteinizing hormone/choriogonadotropin receptor (LHCGR) mRNA expression in follicle-stimulating hormone (FSH)-stimulated human cumulus granulosa cells. Addition of human chorionic gonadotropin was not able to elicit maximal response of ovulatory genes amphiregulin, epiregulin, and progesterone receptor. T-2 toxin reduced mRNA levels of CYP19A1 and steroidogenic acute regulatory protein (STAR) and lowered FSH-stimulated estradiol and progesterone production. Mechanistic experiments demonstrated that T-2 toxin decreased FSH-stimulated cyclic adenosine monophosphate (cAMP) production. Addition of total PDE inhibitor 3-isobutyl-1-methylxanthine prevented T-2 toxin's action on LHCGR, STAR, and CYP19A1 mRNA expression in FSH-stimulated human cumulus granulosa cells. Furthermore, T-2 toxin partially decreased 8-bromoadenosine 3'5'-cyclic monophosphate (8-Br-cAMP)-stimulated LHCGR and STAR, but did not affect 8-Br-cAMP-stimulated CYP19A1 mRNA expression in human cumulus granulosa cells. Overall, our data indicate that environmentally relevant dose of T-2 toxin decreases steroidogenesis and ovulatory potency in human cumulus granulosa cells probably through activation of PDE, thus posing a significant risk for female fertility.

Rosiglitazone increases expression of steroidogenic acute regulatory protein and progesterone production through PPARγ–EGFR–ERK1/2 in human cumulus granulosa cells

The mechanism by which rosiglitazone (ROSI: a thiazolidinedione (TZD)) affects steroid production in undifferentiated human granulosa cells is not known. In this study, cultured human cumulus granulosa cells were exposed to ROSI and pharmacological inhibitors of the extracellular signal-regulated kinase 1/2 (ERK1/2), epidermal growth factor receptor (EGFR) and peroxisome proliferator-activated receptor gamma (PPARγ) signalling pathways. Expression of progesterone biosynthetic enzymes, PPARγ and PPARα, progesterone production and ERK1/2 activation were analysed. After 48h, 30μM ROSI increased STAR, 3βHSD and PPARγ mRNA and elevated progesterone production in human cumulus granulosa cells. Addition of ERK1/2 (U0126), EGFR (AG1478) and PPARγ (GW9662) inhibitors prevented the ROSI-induced STAR mRNA expression and progesterone production after 48h. Inhibition of PPARγ, but not EGFR or ERK1/2, decreased the PPARγ mRNA levels induced by ROSI in human cumulus granulosa cells after 48h. On the other hand, U0126 and GW9662 prevented the ROSI-induced increase in PPARγ transcripts after 6h. Western blot analysis showed that ROSI induced a rapid ERK1/2 activation, which was prevented by inhibition of ERK1/2, EGFR and PPARγ in human cumulus granulosa cells. Overall, these data suggested that PPARγ, EGFR and ERK1/2 were involved in the stimulatory effect of ROSI on STAR expression and progesterone production in undifferentiated human cumulus granulosa cells.

Atrazine suppresses FSH-induced steroidogenesis and LH-dependent expression of ovulatory genes through PDE-cAMP signaling pathway in human cumulus granulosa cells

Atrazine (ATR) alters female reproductive functions in different animal species. Here, we analyzed whether ATR disturbs steroidogenic and ovulatory processes in hormone-stimulated human cumulus granulosa cells and mechanism of its action. Results showed that treatment of human cumulus granulosa cells with 20 μM ATR for 48 h resulted in lower FSH-stimulated estradiol and progesterone production. ATR reduced mRNA levels of aromatase (CYP19A1), steroidogenic acute regulatory protein (STAR) and luteinizing hormone/choriogonadotropin receptor (LHCGR). Addition of hCG 48 h after FSH and ATR treatment did not trigger maximal expression of the ovulatory genes amphiregulin (AREG) and epiregulin (EREG). Mechanistic experiments showed that ATR activated cPDE and decreased cAMP level. Addition of total PDE and specific PDE4 inhibitors, IBMX and rolipram, prevented ATR's action on CYP19A1 and STAR mRNA expression in FSH-stimulated human cumulus granulosa cells. This study suggests that ATR alters steroidogenesis and ovulatory process in human cumulus granulosa cells jeopardizing female reproduction.

Bisphenol A decreases progesterone synthesis by disrupting cholesterol homeostasis in rat granulosa cells

Bisphenol A (BPA) is an endocrine disruptor used in a variety of consumer products. Exposure to BPA leads to alterations in steroidogenesis of ovarian granulosa cells. Here, we analyzed the mechanism by which BPA alters progesterone biosynthesis in immature rat granulosa cells. BPA increased expression of steroidogenic acute regulatory protein (StAR), cholesterol side-chain cleavage enzyme and 3β-hydroxysteroid dehydrogenase in granulosa cells; however, BPA prevented the basal and the FSH-induced progesterone production. BPA caused sequestration of cholesterol to the perinuclear area, as evident by the Filipin staining. BPA decreased mRNA expression of ATP binding cassette transporter-A1 (Abca1) and increased level of sterol regulatory element binding protein 1. Addition of exogenous cell-permeable cholesterol restored the effect of BPA on Abca1 and Star mRNA expression and partially reversed BPA's effect on progesterone production. These results indicate that exposure to BPA disrupts cholesterol homeostasis leading to decreased progesterone production in immature rat granulosa cells.

Adverse stimulation of 4-nonylphenol in abnormal reproductive organs of female chickens

4-Nonylphenol (4-NP) is a known endocrine disrupting chemical and a persistent environmental contaminant. However, the 4-NP caused mechanism of reproductive toxicity still remains largely unknown in birds. In this study, female chickens (Hy-Line Variety White) were dosed via oral gavage in the early laying period with 0, 50, 100, and 200 mg 4-NP/kg/d for 60 days. Food intake and weight increase were monitored in this organism to investigate chicken growth and development. Moreover, pathological changes of reproductive organs, serum hormone, and mRNA changes on the HPOA were detected. The results showed that gonad development and maturity were retarded in female chickens, and the circulating concentrations of sex hormones were disordered in 4-NP-treated chicken. In 4-NP exposed animals, the mRNA expressions of GnRH and PRLH in hypothalamus and FSH and LH in pituitary were significantly unregulated by 4-NP. In addition, expressions of FSHR and LHR were down-regulated in ovaries of the 4-NP-treatment group, while the levels of stAR, P450scc, P450arom, 3β-HSD, and 17β-HSD were up-regulated in ovaries. Furthermore, expression of ERα in the ovaries of chicken was up-regulated, however, no significant change was observed for ERβ expression. Our results suggest that granulosa cells were an important target and severely disturbed by 4-NP.

Atrazine exposure decreases the activity of DNMTs, global DNA methylation levels, and dnmt expression

Atrazine, a herbicide used on agricultural crops is widely applied in the Midwestern United States as well as other areas of the globe. Atrazine frequently contaminates potable water supplies and is a suspected endocrine disrupting chemical. Previous studies have reported morphological, hormonal, and molecular alterations due to developmental and adulthood atrazine exposure; however, studies examining epigenetic alterations are limited. In this study, the effects of atrazine exposure on DNA methyltransferase (DNMT) activity and kinetics were evaluated. Global DNA methylation levels and dnmt expression in zebrafish larvae exposed to 0, 3, or 30 parts per billion (ppb) atrazine throughout embryogenesis was then assessed. Results indicate that atrazine significantly decreased the activity of maintenance DNMTs and that the inhibition mechanism can be described using non-competitive Michaelis-Menten kinetics. Furthermore, results show that an embryonic atrazine exposure decreases global methylation levels and the expression of dnmt4 and dnmt5. These findings indicate that atrazine exposure can decrease the expression and activity of DNMTs, leading to decreased DNA methylation levels.

Persistent testicular structural and functional alterations after exposure of adult rats to atrazine

Atrazine is an endocrine disruptor affecting testicular steroidogenesis, and promoting testicular atrophy and 3β-HSD reduction. However, it remains unknown whether these effects are reversible or permanent. To address this issue was the aim of this study. Exposition of rats to 200mg/kg of atrazine resulted in transient increase in testicular weight, seminiferous tubules dilation and atrophy, and reduction in Leydig cell 3β-HSD. Testicular atrophy and 3β-HSD reduction were more pronounced after the recovery period of 75days. There was increase in aromatase expression after long-term exposure but it returned to control level after recovery. Moreover, there was increase in ED1^-/ED2⁺, ED1⁺/ED2⁺ and ED1⁺/ED2^- macrophages, in the recovery group. These macrophages were positive for 3β-HSD, thereby raising possibility of their involvement in steroidogenesis. These findings further emphasize the adverse effects of atrazine on male reproduction, highlighting that testicular damages may be irreversible even after a recovery period longer than the spermatogenic cycle.

Atrazine exposure elicits copy number alterations in the zebrafish genome

Atrazine is an agricultural herbicide used throughout the Midwestern United States that frequently contaminates potable water supplies resulting in human exposure. Using the zebrafish model system, an embryonic atrazine exposure was previously reported to decrease spawning rates with an increase in progesterone and ovarian follicular atresia in adult females. In addition, alterations in genes associated with distinct molecular pathways of the endocrine system were observed in brain and gonad tissue of the adult females and males. Current hypotheses for mechanistic changes in the developmental origins of health and disease include genetic (e.g., copy number alterations) or epigenetic (e.g., DNA methylation) mechanisms. As such, in the current study we investigated whether an atrazine exposure would generate copy number alterations (CNAs) in the zebrafish genome. A zebrafish fibroblast cell line was used to limit detection to CNAs caused by the chemical exposure. First, cells were exposed to a range of atrazine concentrations and a crystal violet assay was completed, showing confluency decreased by ~60% at 46.3μM. Cells were then exposed to 0, 0.463, 4.63, or 46.3μM atrazine and array comparative genomic hybridization completed. Results showed 34, 21, and 44 CNAs in the 0.463, 4.63, and 46.3μM treatments, respectively. Furthermore, CNAs were associated with previously reported gene expression alterations in adult male and female zebrafish. This study demonstrates that atrazine exposure can generate CNAs that are linked to gene expression alterations observed in adult zebrafish exposed to atrazine during embryogenesis providing a mechanism of the developmental origins of atrazine endocrine disruption.

Exposure to the widely used herbicide atrazine results in deregulation of global tissue-specific RNA transcription in the third generation and is associated with a global decrease of histone trimethylation in mice

The epigenetic events imposed during germline reprogramming and affected by harmful exposure can be inherited and transferred to subsequent generations via gametes inheritance. In this study, we examine the transgenerational effects promoted by widely used herbicide atrazine (ATZ). We exposed pregnant outbred CD1 female mice and the male progeny was crossed for three generations with untreated females. We demonstrate here that exposure to ATZ affects meiosis, spermiogenesis and reduces the spermatozoa number in the third generation (F3) male mice. We suggest that changes in testis cell types originate from modified transcriptional network in undifferentiated spermatogonia. Importantly, exposure to ATZ dramatically increases the number of transcripts with novel transcription initiation sites, spliced variants and alternative polyadenylation sites. We found the global decrease in H3K4me3 occupancy in the third generation males. The regions with altered H3K4me3 occupancy in F3 ATZ-derived males correspond to altered H3K4me3 occupancy of F1 generation and 74% of changed peaks in F3 generation are associated with enhancers. The regions with altered H3K4me3 occupancy are enriched in SP family and WT1 transcription factor binding sites. Our data suggest that the embryonic exposure to ATZ affects the development and the changes induced by ATZ are transferred up to three generations.

Embryonic Atrazine Exposure Elicits Alterations in Genes Associated with Neuroendocrine Function in Adult Male Zebrafish

The developmental origins of health and disease (DOHaD) hypothesis states that exposure to environmental stressors early in life can elicit genome and epigenome changes resulting in an increased susceptibility of a disease state during adulthood. Atrazine, a common agricultural herbicide used throughout the Midwestern United States, frequently contaminates potable water supplies and is a suspected endocrine disrupting chemical. In our previous studies, zebrafish was exposed to 0, 0.3, 3, or 30 parts per billion (μg/l) atrazine through embryogenesis, rinsed, and allowed to mature to adulthood. A decrease in spawning was observed with morphological alterations in offspring. In addition, adult females displayed an increase in ovarian progesterone and follicular atresia, alterations in levels of a serotonin metabolite and serotonin turnover in brain tissue, and transcriptome changes in brain and ovarian tissue supporting neuroendocrine alterations. As reproductive dysfunction is also influenced by males, this study assessed testes histology, hormone levels, and transcriptomic profiles of testes and brain tissue in the adult males. The embryonic atrazine exposure resulted in no alterations in body or testes weight, gonadosomatic index, testes histology, or levels of 11-ketotestosterone or testosterone. To further investigate potential alterations, transcriptomic profiles of adult male testes and brain tissue was completed. This analysis demonstrated alterations in genes associated with abnormal cell and neuronal growth and morphology; molecular transport, quantity, and production of steroid hormones; and neurotransmission with an emphasis on the hypothalamus-pituitary-adrenal and hypothalamus-pituitary-thyroid axes. Overall, this data indicate future studies should focus on additional neuroendocrine endpoints to determine potential functional impairments.

Development of a combined method to assess the complex effect of atrazine on sex steroid synthesis in H295R cells

The aim of the study was to develop a rapid, cost-effective combined testing method to assess the indirect effect of compounds interfering with sex steroid synthesis and to determine complex effects of atrazine on estrogen and androgen synthesis in vitro on H295R human cell line. Steroidogenic assay was performed on H295R human adrenocortical carcinoma cell line. Instead of standard analytical methods, bioluminescence bioreporter assays (Saccharomyces cerevisiae BLYES and BLYAS) were used to measure estrogenic and androgenic effects of sex steroid hormones released by human cells in response to atrazine. Atrazine resulted in elevated estrogen production presumably due to its well documented inductive effect on aromatase on H295R cell line, detected by BLYES. Interestingly, results of BLYAS test showed concentration-dependent increase of androgen production in H295R cells. That indicates that atrazine can not only increase estrogen level via aromatase induction, but may interfere in androgen synthesis as well. The combined method allows us to assess the androgenic and estrogenic effect of sex steroids produced by human cells in increased or decreased quantity as a result of the different chemicals, without determining specific analytical measurement endpoints, by using the yeast based bioluminescent bioreporter test.

Perturbation of epigenetic processes by doxorubicin in the mouse testis

Epigenetic processes play a major role in normal mammalian development, particularly during gametogenesis and early embryogenesis. Thus, perturbation of epigenetic processes in the testis by xenobiotics could have a major impact on testicular function and fertility, and potentially affect the development and health of subsequent generations. There has been substantial research into the epigenetic toxicity of environmental exposures over the last decade. However, few studies have focussed on pharmaceutical drugs, which due to the nature of their use are typically found at much higher concentrations within exposed individuals than environmental chemicals. Here, we investigated genome-wide changes in testicular mRNA transcription, microRNA expression and DNA methylation to assess the contribution of epigenetic mechanisms to the testicular toxicity induced by doxorubicin (DOX) as a representative, widely used and well-characterised anti-cancer drug. We demonstrated that DOX is able to induce transcriptional, microRNA and DNA methylation changes, which perturb pathways involved in stress/cell death and survival and testicular function and lead to germ cell loss and reproductive organ damage. This identified potential novel mechanisms of DOX-induced testicular toxicity for further focussed investigations. Such work is required to fully assess the role of epigenetics in toxicity, determine whether single and/or multigenerational epigenetic toxicity is a real public health concern, and begin to develop and incorporate relevant epigenetic endpoints into regulatory toxicology.

Embryonic atrazine exposure alters zebrafish and human miRNAs associated with angiogenesis, cancer, and neurodevelopment

MicroRNAs (miRNAs) are short, single-stranded RNA that regulate post-transcriptional control of mRNA translation. Knowledge on the role of these critical regulators in toxicological responses in increasing, but is still limited. Atrazine is a herbicide used throughout the Midwestern US that is reported to frequently contaminate potable water supplies above the maximum contaminant level of 3 parts per billion. Atrazine is a suspected endocrine disrupting chemical and studies have begun to investigate the genetic mechanisms of toxicity; however, studies investigating epigenetic mechanisms are limited. In this study both zebrafish and human miRNAs were significantly altered in response to an embryonic atrazine exposure of 0.3, 3, or 30 ppb in zebrafish. Altered miRNAs are known to play a role in angiogenesis, cancer, or neuronal development, differentiation, and maturation. Targeted analysis of altered human miRNAs with genes previously identified to be altered by atrazine exposure revealed several targets linked to cell cycle and cell signaling. Further analysis of hsa-miRNA-126-3p, which had altered expression in all three atrazine treatments at 72 hpf, revealed alterations also occurred at 60 hpf in the 30 ppb treatment group. Results from this study indicate miRNA deregulation in zebrafish and human miRNAs following an embryonic atrazine exposure in zebrafish.

An embryonic atrazine exposure results in reproductive dysfunction in adult zebrafish and morphological alterations in their offspring

The herbicide atrazine, a suspected endocrine disrupting chemical (EDC), frequently contaminates potable water supplies. Studies suggest alterations in the neuroendocrine system along the hypothalamus-pituitary-gonadal axis; however, most studies address either developmental, pubertal, or adulthood exposures, with few investigations regarding a developmental origins hypothesis. In this study, zebrafish were exposed to 0, 0.3, 3, or 30 parts per billion (ppb) atrazine through embryogenesis and then allowed to mature with no additional chemical exposure. Reproductive function, histopathology, hormone levels, offspring morphology, and the ovarian transcriptome were assessed. Embryonic atrazine exposure resulted in a significant increase in progesterone levels in the 3 and 30 ppb groups. A significant decrease in spawning and a significant increase in follicular atresia in the 30 ppb group were observed. In offspring, a decrease in the head length to body ratio in the 30 ppb group, along with a significant increase in head width to body ratio in the 0.3 and 3 ppb groups occurred. Transcriptomic alterations involved genes associated with endocrine system development and function, tissue development, and behavior. This study provides evidence to support atrazine as an EDC causing reproductive dysfunction and molecular alterations in adults exposed only during embryogenesis and morphological alterations in their offspring.

Transcriptional profiles of glutathione-S-Transferase isoforms, Cyp, and AOE genes in atrazine-exposed zebrafish embryos

Glutathione-S-transferase (GST) superfamily consists of multiple members involved in xenobiotic metabolism. Expressional pattern of the GST isoforms in adult fish has been used as a biomarker of exposure to environmental chemicals. However, GST transcriptional responses vary across organs, thus requiring a cross-tissue examination of multiple mRNAs for GST profiling in an animal after chemical exposure. Zebrafish embryos express all GST isoforms as adult fish and could therefore represent an alternative model for identification of biomarkers of exposure. To evaluate such a possibility, we studied a set of cytosolic and microsomal GST isoform-specific expression profiles in the zebrafish embryos after exposure to atrazine, a widely used herbicide. Expression of the GST isoforms was compared with that of CYP genes involved in the phase I of xenobiotic metabolism and antioxidant enzyme (AOE) genes. Using quantitative real-time PCR, we showed dynamic changes in the expressional pattern of twenty GST isoforms, cyp1a, cyp3a65, ahr2, and four AOEs in early development of zebrafish. Acute (48 and 72 h) exposure of 24 h-old embryos to atrazine, from environmentally relevant (0.005 mg/L) to high (40 mg/L) concentrations, caused a variety of transient, albeit minor changes (<2.5-fold) in the GST isoforms, ahr2 and AOE genes response. However, expression of cyp1a and cyp3a65 mRNA was markedly and consistently induced by high doses of atrazine (5 and 40 mg/L). In summary, an analysis of the response of multiple systems in the zebrafish embryos provided a comprehensive understanding of atrazine toxicity and its potential impact on biological processes.

Atrazine triggers developmental abnormality of ovary and oviduct in quails (Coturnix Coturnix coturnix) via disruption of hypothalamo-pituitary-ovarian axis

There has been a gradual increase in production and consumption of atrazine (ATR) in agriculture to meet the population rising demands. Female reproduction is necessary for growth and maintenance of population. However, ATR impact on females and particularly ovarian developmental toxicity is less clear. The aim of this study was to define the pathways by which ATR exerted toxic effects on ovarian development of ovary and hypothalamo-pituitary-ovarian (HPO) axis. Female quails were dosed by oral gavage from sexual immaturity to maturity with 0, 50, 250 and 500 mg ATR/kg/d for 45 days. ATR had no effect on mortality but depressed feed intake and growth and influenced the biochemical parameters. Notably, the arrested development of ovaries and oviducts were observed in ATR-exposed quails. The circulating concentrations of E2, P, LH and PRL were unregulated and FSH and T was downregulated in ATR-treated quails. The mRNA expression of GnRH in hypothalamo and LH in pituitary and FSH in ovary was downregulated significantly by ATR exposure and FSH and PRL in pituitary were upregulated. ATR exposure upregulated the level of P450scc, P450arom, 3β-HSD and 17β-HSD in ovary and downregulated ERβ expression in female quails. However, ATR did not change ERα expression in ovary. This study provides new insights regarding female productive toxicology of ATR exposure. Ovary and oviduct in sexually maturing females were target organs of ATR-induced developmental toxicity. We propose that ATR-induced developmental abnormality of ovary and oviduct is associated with disruption of gonadal hormone balance and HPO axis in female quails.

Atrazine Exposure and Reproductive Dysfunction through the Hypothalamus-Pituitary-Gonadal (HPG) Axis

Endocrine disrupting chemicals (EDC) are exogenous agents that alter endogenous hormone signaling pathways. These chemicals target the neuroendocrine system which is composed of organs throughout the body that work alongside the central nervous system to regulate biological processes. Of primary importance is the hypothalamic-pituitary-gonadal (HPG) axis which is vital for maintaining proper reproductive function. Atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) is a pre-emergent herbicide used to prevent the growth of weeds on various crops. This herbicide is reported to widely contaminate potable water supplies everywhere it is applied. As such, the European Union banned the use of atrazine in 2004. Currently the United States Environmental Protection Agency regulates atrazine at 3 parts per billion (ppb; μg/L) in drinking water, while the World Health Organization recently changed their drinking water guideline to 100 ppb. Atrazine is implicated to be an EDC that alters reproductive dysfunction by targeting the HPG axis. However, questions remain as to the human health risks associated with atrazine exposure with studies reporting mixed results on the ability of atrazine to alter the HPG axis. In this review, the current findings for atrazine’s effects on the HPG axis are examined in mammalian, anuran, and fish models and in epidemiological studies.

The epigenetic processes of meiosis in male mice are broadly affected by the widely used herbicide atrazine

BACKGROUND

Environmental factors such as pesticides can cause phenotypic changes in various organisms, including mammals. We studied the effects of the widely used herbicide atrazine (ATZ) on meiosis, a key step of gametogenesis, in male mice.

METHODS

Gene expression pattern was analysed by Gene-Chip array. Genome-wide mapping of H3K4me3 marks distribution was done by ChIP-sequencing of testis tissue using Illumina technologies. RT-qPCR was used to validate differentially expressed genes or differential peaks.

RESULTS

We demonstrate that exposure to ATZ reduces testosterone levels and the number of spermatozoa in the epididymis and delays meiosis. Using Gene-Chip and ChIP-Seq analysis of H3K4me3 marks, we found that a broad range of cellular functions, including GTPase activity, mitochondrial function and steroid-hormone metabolism, are affected by ATZ. Furthermore, treated mice display enriched histone H3K4me3 marks in regions of strong recombination (double-strand break sites), within very large genes and reduced marks in the pseudoautosomal region of X chromosome.

CONCLUSIONS

Our data demonstrate that atrazine exposure interferes with normal meiosis, which affects spermatozoa production.

Atrazine-Mediated Disruption of Steroidogenesis in BLTK1 Murine Leydig Cells

Atrazine (ATR) is a broad-spectrum triazine herbicide that disrupts steroidogenesis resulting in reproductive and developmental toxicity at high doses. Mouse BLTK1 Leydig cells were used as a steroidogenic model to investigate the effects of ATR on testosterone (T) biosynthesis. Induction of steroidogenesis by 3 ng/ml recombinant human chorionic gonadotropin (rhCG) induced intracellular 3',5' cyclic adenosine monophosphate (cAMP) approximately 20-fold and T approximately 3-fold at 4 h. Co-treatment with 300 μM ATR super-induced cAMP levels 100-fold yet antagonized rhCG-mediated induction of T approximately 20% at 4 h. ATR inhibited cAMP-specific phosphodiesterase (cPDE) with an IC50 of ≥98 μM, suggesting cPDE inhibition contributes to the super-induction of cAMP. However, concentrations of up to 3 mM db-cAMP did not antagonize rhCG induction of T levels, suggesting cAMP super-induction alone does not decrease T biosynthesis. Western analysis of cAMP-activated protein kinase A (PKA) target proteins identified ATR-mediated concentration-dependent alterations in phosphorylation including phospho-CREB. These results suggest the cPDE inhibition by ATR and super-induction of cAMP are independent of effects on T levels, and that altered phosphorylation of key steroidogenic regulatory proteins may underlie ATR-mediated disruption of steroidogenesis.

HBCDD-induced sustained reduction in mitochondrial membrane potential, ATP and steroidogenesis in peripubertal rat Leydig cells

Hexabromocyclododecane (HBCDD), a brominated flame retardant added to various consumer products, is a ubiquitous environmental contaminant. We have previously shown that 6-hour exposure to HBCDD disturbs basal and human chorionic gonadotropin (hCG)-induced steroidogenesis in rat Leydig cells. Reduction in mitochondrial membrane potential (ΔΨm) and cAMP production was also observed. Here, we further expanded research on the effect of HBCDD on Leydig cells by using a prolonged exposure scenario. Cells were incubated in the presence of HBCDD during 24h and then treated with HBCDD+hCG for additional 2h. Results showed that HBCDD caused a sustained reduction in ATP level after 24h of exposure, which persisted after additional 2-hour treatment with HBCDD+hCG. cAMP and androgen accumulations measured after 2h of HBCDD+hCG treatment were also inhibited. Real-time PCR analysis showed significant inhibition in the expression of genes for steroidogenic enzymes, luteinizing hormone receptor, regulatory and transport proteins, and several transcription factors under both treatment conditions. Western blot analysis revealed a decreased level of 30kDa steroidogenic acute regulatory protein (StAR) after HBCDD+hCG treatment. In addition, HBCDD decreased the conversion of 22-OH cholesterol to pregnenolone and androstenedione to testosterone, indicating loss of the activity of cytochrome P450C11A1 (CYP11A1) and 17β-hydroxysteroid dehydrogenase (HSD17β). Cell survival was not affected, as confirmed by cytotoxicity and trypan blue tests or DNA fragmentation analysis. In summary, our data showed that HBCDD inhibits ATP supply, most likely through a decrease in ΔΨm, and targets multiple sites in the steroidogenic pathway in Leydig cells.

Atrazine-induced elevation or attenuation of the LH surge in the ovariectomized, estrogen-primed female rat: role of adrenal progesterone

Multiple exposures to the herbicide atrazine (ATRZ) were shown to suppress the LH surge in both cycling female rats and those ovariectomized (OVX) and primed with estradiol (E2). A single ATRZ administration was found to induce a prompt and marked increase in progesterone (P4). As exogenous P4 is known to have a differential effect on the LH surge depending on its temporal relationship with the surge, it was hypothesized that a single treatment in an OVX, E2-primed rat would augment the surge, whereas several exposures would cause a decrease. Following four daily treatments with 100 mg/kg, LH surge was suppressed. In contrast, a single ATRZ exposure elevated the surge. Two treatments were without effect. The single administration caused a large increase in P4 at 30 and 60 min that was likely attributable to adrenal secretion. Four exposures also elevated P4 after the final treatment, although the duration of the increase was shortened. A single treatment with 0, 10, 30, and 100 mg/kg ATRZ showed similar elevations at the highest concentration in P4, the LH peak, and area under the curve (AUC), whereas four exposures reduced the AUC. An increase at 1 h in the expression of Kiss1 in the anteroventral periventricular nucleus suggests that this regional kisspeptin neuronal population has a role in the ATRZ augmentation of the surge. These data support the hypothesis that ATRZ-induced changes in adrenal P4 can either augment or attenuate the surge depending on the temporal proximity of exposure to the rise in LH.

Transcriptome alterations following developmental atrazine exposure in zebrafish are associated with disruption of neuroendocrine and reproductive system function, cell cycle, and carcinogenesis

Atrazine, a herbicide commonly applied to agricultural areas and a common contaminant of potable water supplies, is implicated as an endocrine-disrupting chemical (EDC) and potential carcinogen. Studies show that EDCs can cause irreversible changes in tissue formation, decreased reproductive potential, obesity, and cancer. The U.S. Environmental Protection Agency considers an atrazine concentration of ≤ 3 ppb in drinking water safe for consumption. The specific adverse human health effects associated with a developmental atrazine exposure and the underlying genetic mechanisms of these effects are not well defined. In this study, zebrafish embryos were exposed to a range of atrazine concentrations to establish toxicity. Morphological, transcriptomic, and protein alterations were then assessed at 72h postfertilization following developmental atrazine exposure at 0, 0.3, 3, or 30 ppb. A significant increase in head length was observed in all three atrazine treatments. Transcriptomic profiles revealed 21, 62, and 64 genes with altered expression in the 0.3, 3, and 30 ppb atrazine treatments, respectively. Altered genes were associated with neuroendocrine and reproductive system development, function, and disease; cell cycle control; and carcinogenesis. There was a significant overlap (42 genes) between the 3 and 30 ppb differentially expressed gene lists, with two of these genes (CYP17A1 and SAMHD1) present in all three atrazine treatments. Increased transcript levels were translated to significant upregulation in protein expression. Overall, this study identifies genetic and molecular targets altered in response to a developmental atrazine exposure to further define the biological pathways and mechanisms of toxicity.

Acute effects of hexabromocyclododecane on Leydig cell cyclic nucleotide signaling and steroidogenesis in vitro

Hexabromocyclododecane (HBCDD), an additive brominated flame retardant routinely added to various consumer products, was reported to have toxic effects upon biota, including endocrine disruption. In this study, the potential toxicity of HBCDD was tested in peripubertal rat Leydig cells in vitro during 6h exposure. HBCDD inhibited human chorionic gonadotropin- and forskolin-supported cAMP accumulation and steroidogenesis. It also inhibited basal cAMP production, but elevated basal steroidogenesis. The expression of several cAMP-dependent genes, including steroidogenic acute regulatory protein, cholesterol side chain cleavage enzyme, and 3β-hydroxysteroid dehydrogenase, was also inhibited by HBCDD treatment. Nevertheless, this was not accompanied by a decrease in steroidogenic acute regulatory protein expression, as documented by western blot analysis, and activity of steroidogenic enzymes, as documented by unaffected steroidogenesis in the presence of permeable 22(R)-hydroxycholesterol. However, HBCDD caused significant decrease in mitochondrial membrane potential in untreated and human chorionic gonadotropin-treated cells. This indicates that HBCDD acute toxicity in Leydig cells reflects changes in mitochondrial membrane potential-dependent cAMP production and basal and cAMP-regulated cholesterol transport. This in turn facilitates basal but inhibits cAMP-dependent steroidogenesis. Acute effects of HBCDD treatment on transcription are also indicative of its sustained effects on Leydig cell function.

Atrazine acts as an endocrine disrupter by inhibiting cAMP-specific phosphodiesterase-4

Atrazine, one of the most commonly used herbicides worldwide, acts as an endocrine disruptor, but the mechanism of its action has not been characterized. In this study, we show that atrazine rapidly increases cAMP levels in cultured rat pituitary and testicular Leydig cells in a concentration-dependent manner, but less effectively than 3-isobutyl-1-methylxanthine, a competitive non-specific inhibitor of phosphodiesterases (PDEs). In forskolin (an activator of adenylyl cyclase)- and probenecid (an inhibitor of cyclic nucleotide transporters)-treated cells, but not in 3-isobutyl-1-methylxanthine-treated cells, atrazine further increased cAMP levels, indicating that inhibition of PDEs accounts for accumulation of cAMP. In contrast to cAMP, atrazine did not alter cGMP levels, further indicating that it inhibits cAMP-specific PDEs. Atrazine-induced changes in cAMP levels were sufficient to stimulate prolactin release in pituitary cells and androgen production in Leydig cells, indicating that it acts as an endocrine disrupter both in cells that secrete by exocytosis of prestored hormones and in cells that secrete by de novo hormone synthesis. Rolipram abolished the stimulatory effect of atrazine on cAMP release in both cell types, suggesting that it acts as an inhibitor of PDE4s, isoforms whose mRNA transcripts dominate in pituitary and Leydig cells together with mRNA for PDE8A. In contrast, immortalized lacto-somatotrophs showed low expression of these mRNA transcripts and several fold higher cAMP levels compared to normal pituitary cells, and atrazine was unable to further increase cAMP levels. These results indicate that atrazine acts as a general endocrine disrupter by inhibiting cAMP-specific PDE4s.

Atrazine effects on antioxidant status and xenobiotic metabolizing enzymes after oral administration in peripubertal male rat

Previously, we reported that in vivo applied atrazine from postnatal day 23 to 50 induced strong inhibition of testicular steroidogenesis. Therefore, the aim of the present study was to investigate, in the same experimental model, the oxidative status in androgen-producing testicular interstitial compartment characterized by diminished steroidogenesis. In parallel, we determined activities of antioxidative and cytochrome P450 (CYP) xenobiotic-metabolizing enzymes in liver. To confirm the results on atrazine induced-inhibition of testicular androgenesis, we measured ex vivo production of androgen in Leydig cells. The results revealed decreased activity of antioxidant enzymes, especially glutathione S-transferase (GST), but also glutathione peroxidase (GSH-Px) and catalase (CAT) in testicular interstitial cells, in parallel with strongly diminished ex vivo basal and agonist-stimulated Leydig cell androgenesis. In liver, atrazine increased the activity of GSH-Px, GST, and CYP1A1/2 enzyme, but not lipid peroxidation. These results indicate that atrazine markedly affects both antioxidant status and androgenesis in peripubertal rats.