17β estradiol induced ROS generation, DNA damage and enzymatic responses in the hepatic tissue of Japanese sea bass

In Vitro metabolism of six representative organic UV stabilizers (OUVs) in marine fish liver microsomes: Kinetics, mechanisms and bioaccumulation evaluation

The ubiquitous occurrence of organic UV stabilizers (OUVs) poses a potential threat to marine fish, but the metabolism of OUVs in the body remains a missing piece of the puzzle in their ecotoxicology. This study investigated the in vitro metabolism of six OUVs in the liver microsomes of an economically valuable marine fish (Lateolabrax japonicus). The depletion of the six OUVs follows first-order kinetics in the microsomes, with in vitro depletion rate constants (kdepl) ranging from 0.23 to 0.40/h. The intrinsic clearance (CLint) of 1H-benzotriazole (BT) was estimated to be 0.0026 μL/(min·mg·protein). The enzyme inhibition experiments and molecular docking results highlight the importance of cytochrome P450 enzyme (CYP) 3A4 in OUVs metabolism. Among the 4 metabolizable compounds, some metabolites from hydroxylation, methylation, acetylation and conjugation were tentatively identified. In addition, the in vitro transformation rates can more accurately predict the whole-body bioconcentration potential via an in vitro to in vivo extrapolation (IVIVE) model.

Dietary exposure to 17α-ethinylestradiol negatively affects reproduction and health parameters of zebrafish (Danio rerio)

Pollution of the aquatic ecosystem by hormone-active substances is a frequently discussed topic these days. Such substances can pass through the sewage treatment plant system and affect aquatic life. This study tested the effect of 17α-ethinylestradiol (EE2) on individual zebrafish (Danio rerio) at an environmentally relevant concentration in fish food (10 μg/kg) and at a concentration 100 times higher (1000 μg/kg). This experiment revealed significant changes in the expression of reproductive genes, an increase in vitellogenin levels and histopathological lesions in the testes after EE2 exposure. Additionally, lipid peroxidation and changes in antioxidant enzyme activities were observed at both tested concentrations, along with morphological changes and increased mortality at the higher concentration. Even the environmentally relevant concentration of EE2 poses a danger to the aquatic organisms as it changes D. rerio's reproductive and health parameters, indicating toxicity at molecular, cell, tissue, and organism levels.

17α-Ethynylestradiol and Levonorgestrel Exposure of Rainbow Trout RTL-W1 Cells at 18 °C and 21 °C Mainly Reveals Thermal Tolerance, Absence of Estrogenic Effects, and Progestin-Induced Upregulation of Detoxification Genes

Fish are exposed to increased water temperatures and aquatic pollutants, including endocrine-disrupting compounds (EDCs). Although each stressor can disturb fish liver metabolism independently, combined effects may exist. To unveil the molecular mechanisms behind the effects of EDCs and temperature, fish liver cell lines are potential models needing better characterisation. Accordingly, we exposed the rainbow trout RTL-W1 cells (72 h), at 18 °C and 21 °C, to ethynylestradiol (EE2), levonorgestrel (LNG), and a mixture of both hormones (MIX) at 10 µM. The gene expression of a selection of targets related to detoxification (CYP1A, CYP3A27, GST, UGT, CAT, and MRP2), estrogen exposure (ERα, VtgA), lipid metabolism (FAS, FABP1, FATP1), and temperature stress (HSP70b) was analysed by RT-qPCR. GST expression was higher after LNG exposure at 21 °C than at 18 °C. LNG further enhanced the expression of CAT, while both LNG and MIX increased the expressions of CYP3A27 and MRP2. In contrast, FAS expression only increased in MIX, compared to the control. ERα, VtgA, UGT, CYP1A, HSP70b, FABP1, and FATP1 expressions were not influenced by the temperature or the tested EDCs. The RTL-W1 model was unresponsive to EE2 alone, sensitive to LNG (in detoxification pathway genes), and mainly insensitive to the temperature range but had the potential to unveil specific interactions.

Behavioral, physiological and biochemical responses and differential gene expression in Mytilus galloprovincialis exposed to 17 alpha-ethinylestradiol and sodium lauryl sulfate

Mixture of contaminants often determine biological responses of marine species, making difficult the interpretation of toxicological data. The pharmaceutical 17 alpha-ethinylestradiol (EE2) and the surfactant Sodium Lauryl Sulfate (SLS) commonly co-occur in the marine environment. This study evaluated the effects of EE2 (125.0 ng/L) and SLS (4 mg/L), acting individually and combined, in the mussel Mytilus galloprovincialis. Contaminated mussels closed their valves for longer periods than control ones, especially in the presence of both contaminants, with longer closure periods immediately after spiking compared to values obtained one day after spiking. Nevertheless, males and females increased their metabolism when in the presence of both contaminants (males) and SLS (females), and independently on the treatment males and females were able to activate their antioxidant and biotransformation defences. Although enhancing defences mussels still presented cellular damage and loss of redox balance, especially noticed in the presence of EE2 for males and SLS for females. Histopathological damage was found at mussel's gills in single and mixture exposure, and qPCR analysis revealed a clear estrogen receptor expression with no additive effect due to combined stressors. The results obtained highlight the harmful capacity of both contaminants but further research on this matter is needed, namely considering different climate change scenarios.

Effect of benzotriazole on oxidative stress response and transcriptional gene expression in Oryzias latipes and Danio rerio embryo

Emerging contaminants (EC) such as benzotriazole are being released into the environment in various ways, therefore it is necessary to understand how organisms are affected by EC. In this study, we exposed medaka (Oryzias latipes) and zebrafish (Danio rerio) during their embryonic period (1 day after hatching) to benzotriazole to investigate its effects on oxidative stress (ROS, GSH, GST, SOD, CAT and MDA) and changes in gene expression patterns. In both medaka and zebrafish, the influence of oxidative stress was confirmed through an increased MDA level and changes in the ROS and GSH levels. Antioxidant enzymes such as GST, CAT, and SOD were affected by benzotriazole; however, medaka and zebrafish showed different patterns in the effects by benzotriazole. Results of oxidative stress genes expression showed that medaka had either no influence or had a decrease in the gene expression profile, whereas zebrafish had a statistically significant increase in the expression of some genes. The cyp1a gene expression was increased in both species. However, vtg gene expression was increased only in zebrafish but decreased in medaka, indicating no estrogenic effects in medaka. Apoptosis genes showed changes in expression in both the species but was these changes were not dose-dependent. However, zebrafish caspase-9 gene expression was increased in all of the exposed groups, suggesting the effects on the intrinsic pathway associated with caspase-9. In conclusion, the results indicate that the toxic effects of benzotriazole differ at various levels in the two small fish medaka and zebrafish embryos.

Updating the use of biochemical biomarkers in fish for the evaluation of alterations produced by pharmaceutical products

The evaluation of toxic effects in stressful environmental conditions can be determined through the imbalance between exogenous factors (environmental contaminants) and enzymatic and non-enzymatic defenses in biological systems. The use of fish for the identification of alterations in biochemical biomarkers provides a comprehensive vision of the effects that pharmaceutical products cause in the aquatic ecosystem, as they are organisms with high sensitivity to contaminants, filtering capacity, and potential for environmental toxicology studies. A wide range of pharmaceuticals can stimulate or alter a variety of biochemical mechanisms, such as oxidative damage to membrane lipids, proteins, and changes in antioxidant enzymes. This review includes a summary of knowledge of the last 20 years, in the understanding of the different biochemical biomarkers generated by exposure to pharmaceuticals in fish, which include different categories of pharmaceutical products: NSAIDs, analgesics, antibiotics, anticonvulsants, antidepressants, hormones, lipid regulators and mixtures. This review serves as a tool in the design of studies for the evaluation of the effects of pharmaceutical products, taking into account the most useful biomarkers, type of matrix, enzyme alterations, all taking the pharmaceutical group of interest.

The Potential Protective Effect of Orange Peel and Selenium against 17β-Estradiol- Induced Chronic Non-Bacterial Prostatitis in Rats

BACKGROUND

Prostate Cancer (PCa) is defined as a major health problem faced by the male population.

AIM

We aimed to investigate the protective effects of Orange Peel Extract (OPE) and/or Selenium (Se) on chronic non-bacterial prostatitis in a rat model.

METHODS

Fifty-six adult male Wistar albino rats were castrated; after 5 days, they were divided randomly into eight groups (n= 7). The control group received saline treatment; while 17β-estradiol (E2) (0.25mg/kg) was injected subcutaneously in rats from Groups V, VI, VII, and VIII to induce chronic non-bacterial prostatitis. They were then treated with OPE (400mg/kg body weight; Groups II, IV, VI, and VIII) and/or sodium selenite (0.5mg/kg body weight; Groups III, IV, VII, and VIII) for 30 days. Interleukin-2 (IL2) and Prostate Cancer Antigen 3 (PCA3) mRNA expressions were determined using qPCR; Prostate-Specific Antigen (PSA) protein expression was determined immunohistochemically. Prostate tissue histology was examined by hematoxylin and eosin staining, and the levels of oxidative stress markers and antioxidant enzymes were measured.

RESULTS

E2 administration significantly increased IL2 and PCA3 mRNA expressions, and PSA protein expression. It also increased the prostate wet weight and body weight, and lipid peroxidation, nitric oxide, TNF-α, and IL-1β levels, decreased the glutathione and antioxidant enzyme levels and caused distinct histological alterations in the prostate gland. OPE and/or Se markedly improved all the studied parameters due to their antioxidant properties and anti-inflammatory effects.

CONCLUSION

OPE and Se showed protective effects against 17β-estradiol-induced chronic non-bacterial prostatitis. These results suggest that protection of chronic non-bacterial prostatitis by OPE+Se combination involves anti-oxidation and anti-inflammation. Moreover, their synergistic mechanism was mostly achieved via the regulation of oxidative stress and inflammation processes.

Reduced lactate dehydrogenase activity in the heart and suppressed sex hormone levels are associated with female-biased mortality during thermal stress in Pacific salmon

Female-biased mortality has been repeatedly reported in Pacific salmon during their upriver migration in both field studies and laboratory holding experiments, especially in the presence of multiple environmental stressors, including thermal stress. Here, we used coho salmon (Oncorhynchus kisutch) to test whether females exposed to elevated water temperatures (18°C) (i) suppress circulating sex hormones (testosterone, 11-ketotestosterone and estradiol), owing to elevated cortisol levels, (ii) have higher activities of enzymes supporting anaerobic metabolism (e.g. lactate dehydrogenase, LDH), (iii) have lower activities of enzymes driving oxidative metabolism (e.g. citrate synthase, CS) in skeletal and cardiac muscle, and (iv) have more oxidative stress damage and reduced capacity for antioxidant defense [lower catalase (CAT) activity]. We found no evidence that a higher susceptibility to oxidative stress contributes to female-biased mortality at warm temperatures. We did, however, find that females had significantly lower cardiac LDH and that 18°C significantly reduced plasma levels of testosterone and estradiol, especially in females. We also found that relative gonad size was significantly lower in the 18°C treatment regardless of sex, whereas relative liver size was significantly lower in females held at 18°C. Further, relative spleen size was significantly elevated in the 18°C treatments across both sexes, with larger warm-induced increases in females. Our results suggest that males may better tolerate bouts of cardiac hypoxia at high temperature, and that thermal stress may also disrupt testosterone- and estradiol-mediated protein catabolism, and the immune response (larger spleens), in migratory female salmon.

17-β-Estradiol: Significant reduction of its toxicity in water treated by photocatalysis

The aim of this study was to assess the efficiency of photocatalysis by TiO₂ on the removal of 17-β-estradiol (E2) (at environmentally relevant concentrations) and the toxicity caused by this emerging pollutant. After 60min of TiO₂/UV treatment at pilot scale (14L), E2 was removed from water approximately 85%. The toxicity was established by using Cyprinus carpio as bioindicator organism and oxidative stress biomarkers (OSB): [lipid peroxidation level (LPX), hydroperoxide content (HPC) and protein carbonyl content (PCC)] and enzymes [superoxide dismutase (SOD) and catalase (CAT)]. It was found that the photocatalytic treatment led to significantly reduce OSB in approximately 85-95%. Thus, it can be concluded that heterogeneous photocatalysis by TiO₂ is an efficient process to eliminate the toxicity caused by E2 and thus to remediate water polluted with this molecule.

Antioxidant responses and DNA damage in primary hepatocytes of Van fish (Alburnus tarichi, Güldenstadt 1814) exposed to nonylphenol or octylphenol

Alkylphenols, a nonionic surface-active agent group, such as nonylphenol (NP) and octylphenol (OP) are important endocrine-disrupting chemicals (EDC). In this study, the dose- and time-dependent effects of NP and OP were investigated in the primary hepatocyte culture of Van Fish. In this study, samples were taken at different times and biochemical parameters were studied separately. The effects of the chemicals used on SOD, CAT, GSH-Px, MDA, and 8-OHdG were investigated in hepatocyte culture. The antioxidants SOD and CAT were observed to increase in all groups in the primary hepatocyte cultures at the 24th hour after NP and OP administration, whereas the GSH-Px level was observed to increase with OP at the 24th hour and with NP at the 48th hour. The MDA level was observed to reach its highest value for both chemicals in the 24th hour, and the 8-OHdG level was observed to increase toward the end of the follow-up time, compared to the control group (p < 0.05). In conclusion, different doses of NP and OP were found to induce an increase in the levels of antioxidants and the MDA level in Van Fish primary hepatocyte culture. DNA damage, on the other hand, may be considered to appear after longer-term exposure to NP and OP.

Effects of Sex Steroids on Fish Leukocytes

In vertebrates, in addition to their classically reproductive functions, steroids regulate the immune system. This action is possible mainly due to the presence of steroid receptors in the different immune cell types. Much evidence suggests that the immune system of fish is vulnerable to xenosteroids, which are ubiquitous in the aquatic environment. In vivo and in vitro assays have amply demonstrated that oestrogens interfere with both the innate and the adaptive immune system of fish by regulating the main leukocyte activities and transcriptional genes. They activate nuclear oestrogen receptors and/or G-protein coupled oestrogen receptor. Less understood is the role of androgens in the immune system, mainly due to the complexity of the transcriptional regulation of androgen receptors in fish. The aim of this manuscript is to review our present knowledge concerning the effect of sex steroid hormones and the presence of their receptors on fish leukocytes, taking into consideration that the studies performed vary as regard the fish species, doses, exposure protocols and hormones used. Moreover, we also include evidence of the probable role of progestins in the regulation of the immune system of fish.

17β-Estradiol induces cyto-genotoxicity on blood cells of common carp (Cyprinus carpio)

17β-Estradiol, a natural hormone present at high concentrations in aquatic ecosystems, affects and modifies endocrine function in animals. In recent years research workers have expressed concern over its potential effects on aquatic organisms; however, little is known about its capacity to induce genetic damage or the pro-apoptotic effects of such damage on fish. Therefore, this study aimed to evaluate 17β-estradiol-induced cyto-genotoxicity in blood cells of the common carp Cyprinus carpio exposed to different concentrations (1 ng, 1 μg and 1 mg L^-1). Peripheral blood samples were collected and evaluated by comet assay, micronucleus test, determination of caspase-3 activity and TUNEL assay at 12, 24, 48, 72 and 96 h of exposure. Increases in frequency of micronuclei, TUNEL-positive cells and caspase-3 activity were observed, particularly at the highest concentration. In contrast, the comet assay detected significant increases at 24 and 96 h with the 1 μg and 1 ng L^-1 concentrations respectively. The set of assays used in the present study constitutes a reliable early warning biomarker for evaluating the toxicity induced by this type of emerging contaminants on aquatic species.

Highly potent host external immunity acts as a strong selective force enhancing rapid parasite virulence evolution

Virulence is often under selection during host-parasite coevolution. In order to increase fitness, parasites are predicted to circumvent and overcome host immunity. A particular challenge for pathogens are external immune systems, chemical defence systems comprised of potent antimicrobial compounds released by prospective hosts into the environment. We carried out an evolution experiment, allowing for coevolution to occur, with the entomopathogenic fungus, Beauveria bassiana, and the red flour beetle, Tribolium castaneum, which has a well-documented external immune system with strong inhibitory effects against B. bassiana. After just seven transfers of experimental evolution we saw a significant increase in parasite induced host mortality, a proxy for virulence, in all B. bassiana lines. This apparent virulence increase was mainly the result of the B. bassiana lines evolving resistance to the beetles' external immune defences, not due to increased production of toxins or other harmful substances. Transcriptomic analyses of evolved B. bassiana implicated the up-regulation of oxidative stress resistance genes in the observed resistance to external immunity. It was concluded that external immunity acts as a powerful selective force for virulence evolution, with an increase in virulence being achieved apparently entirely by overcoming these defences, most likely due to elevated oxidative stress resistance.

Comprehensive analysis of lncRNAs and mRNAs in skeletal muscle of rainbow trout (Oncorhynchus mykiss) exposed to estradiol

Estradiol (E2) is a steroid hormone that negatively affects muscle growth in rainbow trout (Oncorhynchus mykiss), but the mechanisms directing with this response are not fully understood. To better characterize the effects of E2 in muscle, we identified differentially regulated mRNAs and lncRNAs in juvenile rainbow trout exposed to E2. Here, we performed next-generation RNA sequencing and comprehensive bioinformatics analyses to characterize the transcriptome profiles, including mRNAs and long noncoding RNAs (lncRNAs), in skeletal muscle of rainbow trout injected with E2. A total of 226 lncRNAs and 253 mRNAs were identified as differentially regulated. We identified crucial pathways, including several signal transduction pathways, hormone response, oxidative response and protein, carbon and fatty acid metabolism pathways. Subsequently, a functional lncRNA-mRNA co-expression network was constructed, which consisted of 681 co-expression relationships between 164 lncRNAs and 201 mRNAs. Moreover, a lncRNA-pathway network was constructed. A total of 65 key lncRNAs were identified that regulate 20 significantly enriched pathways. Overall, our analysis provides insights into mRNA and lncRNA networks in rainbow trout skeletal muscle and their regulation by E2 while understanding the molecular mechanism of lncRNAs.

Multiwall Carbon Nanotube-Induced Apoptosis and Antioxidant Gene Expression in the Gills, Liver, and Intestine of Oryzias latipes

Multiwall carbon nanotubes (MWCNTs) have many attractive properties with potential applications in various fields. Despite their usefulness, however, the associated waste can be hazardous to the environment. To examine adverse effects in aquatic environments, Oryzias latipes were exposed to MWCNTs dispersed in water for 14 days and apoptosis and antioxidant gene expression were observed. This work showed that in gills exposed to 100 mg/L MWCNTs for 4 days, there was significant p53, caspase-3 (Cas3), caspase-8 (Cas8), and caspase-9 (Cas9) gene expression relative to the controls, while catalase (CAT) and glutathione-S-transferase (GST) expression were reduced. At 14 days, CAT, GST, and metallothionein (MT) were induced significantly in the gills and Cas3, Cas8, and Cas9 were induced in the liver. No significant gene induction was seen in intestine. Intracellular reactive oxygen species (ROS) were increased significantly only at 14 days. Histologically, no apoptosis was observed with exposure to 100 mg/L MWCNTs for 21 days. The gills were more sensitive to MWCNT toxicity than the other organs. Males had higher apoptosis gene induction than females. These results demonstrated that MWCNTs could cause apoptosis in a manner influenced by tissue and gender in aqueous environments.

A candidate short-term toxicity test using Ampelisca brevicornis to assess sublethal responses to pharmaceuticals bound to marine sediments

Lethal and sublethal responses related to different phases of metabolism (phases I and II enzymatic activities), neurotoxicity (acetylcholinesterase activity), oxidative stress (lipid peroxidation and antioxidant enzyme activities), and genetic damage (DNA strand breaks) were analysed to assess the possible adverse effects of pharmaceuticals bound to marine sediments. The crustacean amphipod Ampelisca brevicornis was chosen as the bioindicator species. Organisms were exposed for 10 days to sediment spiked with pharmaceutical compounds frequently used and previously detected in the environment: carbamazepine (CBZ), ibuprofen (IBP), fluoxetine (FX), 17α-ethynylestradiol (EE2), propranolol (PRO), and caffeine (CAF). Short-term bioassay to evaluate amphipod mortality was recommended to assess pollution by CBZ, FX, and PRO. IBP and PRO were metabolized by phases I and II detoxification enzymatic activities. Oxidative stress was caused by PRO and CAF. Contrary to expected results, DNA damage (strand breaks) decreased after the exposure of amphipods to sediment spiked with IBP, FX, EE2, PRO, and CAF (including environmental concentrations). FX was neurotoxic to amphipods. The battery of biomarkers tested allowed the assessment of bioavailability, oxidative stress, genotoxicity, and neurotoxicity of the pharmaceuticals analysed. The results of this study suggested that pharmaceutical products at concentrations currently found in the environment might cause a wide variety of adverse effects (based on laboratory studies). The results obtained here are useful for environmental risk assessment of marine sediments contaminated by pharmaceuticals. Nevertheless, more research is needed using field-based marine sediments.

Comparative study of 17 β-estradiol on endocrine disruption and biotransformation in fingerlings and juveniles of Japanese sea bass Lateolabrax japonicus

Estrogenic contaminants in the aquatic environment are associated with endocrine disruption and feminization in fish. The effects of endocrine disrupting chemicals (EDCs) on fish have been well documented. However, very few studies have focused on 17 β-estradiol (E2) and its effects on endocrine system and biotransformation in a single prolonged exposure. This study investigated changes in the levels of serotonin (5-hydroxytryptamine) and acetyl choline esterase (AchE) in brain, cortisol in plasma and Ethoxyresorufin-O-deethylase (EROD) activity in gill of two different size groups (fingerlings and juveniles) of Japanese sea bass (Lateolabrax japonicus) upon exposure to two sub-lethal concentrations (200 and 2000 ng L(-1)) of E2 for 30 d. The results indicate that cortisol level and EROD activity significantly increased in both groups, whereas serotonin level increased in juveniles and decreased in fingerlings due to E2 exposure. The correlation analysis revealed that E2 significantly affected the endocrine and biotransformation systems in both age groups.

Benzo[a]pyrene modulates the biotransformation, DNA damage and cortisol level of red sea bream challenged with lipopolysaccharide

In animals, biotransformation and the immune system interact with each other, however, knowledge of the toxic mechanism of benzo[a]pyrene (BaP) on these two systems is not well known. The present study investigated the toxic effects of BaP on the biotransformation system, cortisol level and DNA integrity of red sea bream (Pagrus major). The results showed that cortisol level was induced under the challenge of lipopolysaccharide (LPS). Short-term exposure (96 h) of BaP at environmental concentration significantly increased the cortisol level, hepatic EROD activity and CYP1A1 mRNA expression. When P. major was exposed to BaP for 14 d followed by LPS challenge this increased the cortisol level, EROD activity and hepatic DNA damage except CYP1A1 mRNA expression. Combined with our previous data, which showed that BaP exposure can modulate the immunologic response in P. major challenged with LPS, a hypothetical adverse outcome pathway of BaP on fish was suggested.

Molecular responses to 17β-estradiol in early life stage salmonids

Environmental estrogens (EE) are ubiquitous in many aquatic environments and biological responses to EEs in early developmental stages of salmonids are poorly understood compared to juvenile and adult stages. Using 17β-estradiol (E2) as a model estrogen, waterborne exposures were conducted on early life stage rainbow trout (Oncorhynchus mykiss; egg, alevin, swim-up fry) and both molecular and physiological endpoints were measured to quantify the effects of E2. To investigate developmental stage-specific effects, laboratory exposures of 1 μg/L E2 were initiated pre-hatching as eyed embryos or post-hatching upon entering the alevin stage. High mortality (∼90%) was observed when E2 exposures were initiated at the eyed embryo stage compared to the alevin stage (∼35% mortality), demonstrating stage-specific sensitivity. Gene expression analyses revealed that vitellogenin was detectable in the liver of swim-up fry, and was highly inducible by 1 μg/L E2 (>200-fold higher levels compared to control animals). Experiments also confirmed the induction of vitellogenin protein levels in protein extracts isolated from head and tail regions of swim-up fry after E2 exposure. These findings suggest that induction of vitellogenin, a well-characterized biomarker for estrogenic exposure, can be informative measured at this early life stage. Several other genes of the reproductive endocrine axis (e.g. estrogen receptors and androgen receptors) exhibited decreased expression levels compared to control animals. In addition, chronic exposure to E2 during the eyed embryo and alevin stages resulted in suppressive effects on growth related genes (growth hormone receptors, insulin-like growth factor 1) as well as premature hatching, suggesting that the somatotropic axis is a key target for E2-mediated developmental and growth disruptions. Combining molecular biomarkers with morphological and physiological changes in early life stage salmonids holds considerable promise for further defining estrogen action during development, and for assessing the impacts of endocrine disrupting chemicals in vivo in teleosts.

Dehydroabietic acid (DHAA) alters metabolic enzyme activity and the effects of 17β-estradiol in rainbow trout (Oncorhynchus mykiss)

Recent studies have shown that dehydroabietic acid (DHAA), a resin acid present in pulp and paper mill effluent, affects liver energy metabolism and may have anti-estrogenic effects in fish. A chronic-exposure toxicity experiment using immature rainbow trout (Oncorhynchus mykiss) was conducted in order to assess the endocrine disrupting and liver metabolic effects of the model estrogen 17β-estradiol (E2) and the wood extractives DHAA and β-sitosterol (BS), regularly present in pulp and paper mill effluents. Exposure to 5ppm of E2 significantly increased hepatosomatic index (HSI), vitellogenin (VTG) and plasma sorbitol dehydrogenase (SDH). This latter effect was reduced by mixing E2 with DHAA, indicating that DHAA does not cause its endocrine disrupting effects indirectly due to liver damage. Exposure to 0.5ppm of DHAA as well as all the DHAA mixed treatments caused significant increases in liver citrate synthase (CS), activity after 7 days, however, the fish returned to control values by 28 days. Results indicate that DHAA may alter metabolic enzyme activity as well as alter the effects of E2 in juvenile rainbow trout.

An integrated assessment of estrogenic contamination and feminization risk in fish in Taihu Lake, China

An integrated approach, combining biological and chemical methods, was used to assess potential exposure to exogenous estrogens and their possible interference with the endocrine system of male goldfish (Carassius auratus) in Taihu Lake. A suite of biomarkers in caged fish after in situ exposure for 28 days, coupled with six selected exogenous estrogens in water, were determined at eight biomonitoring stations. The compounds estrone, 17β-estradiol (E2), estriol, 17α-ethinylestradiol (EE2), bisphenol-A and diethylstilbestrol were detected in most of the samples and the concentrations of total estradiol equivalent (EEQ) ranged between 5.69 and 17.8 ng/L. E2 and EE2 were thought to be the major causal agents responsible for the estrogenic activities. Elevated serum vitellogenin and E2, gonadal DNA damage and reduced gonadosomatic index were observed in fish collected from most stations. The integrated biomarker response (IBR) index showed good agreement with the observed total EEQ levels in water, and feminization risk in fish may be present in northern Taihu Lake, especially in Meiliang Bay and Zhushan Bay.

Influence of divalent metal ions on E2-induced ER pathway in goldfish (Carassius auratus) hepatocytes

Metal ions existing in the environment could influence the estrogen pathway in aquatic animal, but the detailed mechanism is still delusive. We here showed that in male Carassius auratus hepatocytes, copper (Cu) or cadmium (Cd), did not directly induce vitellogenin (VTG) expression. Interestingly, co-exposure with Cd²⁺ (or Cu²⁺) and 17-β-estradiol (E2) greatly increased the VTG level, comparing with single treatment of E2. Meanwhile, Cd²⁺ or Cu²⁺ (but not E2) triggers HSP70 expression. But, mixture of Cd²⁺ or Cu²⁺ with E2 did not obviously raise HSP70 level. E2 also had no obvious effect on reactive oxygen species. Co-treatment of Cd²⁺ and E2 showed no obvious increase compared to single treatment with Cd²⁺. We further assume that Cd²⁺-involved oxidative stress generates misfolded proteins, resulting in the competition of HSP70 proteins from a heterocomplex (with estrogen receptor). Thus, dissociation of the heterocomplex actives the receptor-ligand binding activity and promotes the E2-induced VTG expression.