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Karthick Rajan D, Mohan K, Rajarajeswaran J, Divya D, Thanigaivel S, Zhang S. Toxic effects of organophosphate pesticide monocrotophos in aquatic organisms: A review of challenges, regulations and future perspectives. ENVIRONMENTAL RESEARCH 2024; 244:117947. [PMID: 38109962 DOI: 10.1016/j.envres.2023.117947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 12/05/2023] [Accepted: 12/12/2023] [Indexed: 12/20/2023]
Abstract
In recent times, usage of pesticide, herbicides and synthetic fertilizers in farming lands has made the environment worse. The pesticide residues and toxic byproducts from agricultural lands were found to contaminate the aquatic ecosystem. The misuse of synthetic pesticide not only affects the environment, but also affects the health status of aquatic organisms. The organophosphate pesticide pollutants are emerging contaminants, which threatens the terrestrial and aquatic ecosystem. Monocrotophos (MCP) is an organophosphate insecticide, utilized on crops including rice, maize, sugarcane, cotton, soybeans, groundnuts and vegetables. MCP is hydrophilic in nature and their solubilizing properties reduce the soil sorption which leads to groundwater contamination. The half-life period of MCP is 17-96 and the half-life period of technical grade MCP is 2500 days if held stable at 38 °C in a container. MCP causes mild to severe confusion, anxiety, hyper-salivation, convulsion and respiratory distress in mammals as well as aquatic animals. The MCP induced toxicity including survival rate, behavioural changes, reproductive toxicity and genotoxicity in different aquatic species have been discussed in this review. Furthermore, the ultimate aim of this review is to highlight the international regulations, future perspectives and challenges involved in using the MCP.
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Affiliation(s)
- Durairaj Karthick Rajan
- Department of Cell Biology, School of Life Sciences, Central South University, Changsha, Hunan, 410013, PR China.
| | - Kannan Mohan
- PG and Research Department of Zoology, Sri Vasavi College, Erode, Tamil Nadu, 638 316, India.
| | - Jayakumar Rajarajeswaran
- Department of Nanobiomaterials, Saveetha School of Engineering, Saveetha Institute of Medical and Technical Sciences, Chennai, 602105, Tamil Nadu, India
| | - Dharmaraj Divya
- Department of Animal Health and Management, Alagappa University, Karaikudi, Tamilnadu, 630003, India
| | - Sundaram Thanigaivel
- Department of Biotechnology, Faculty of Science and Humanities, SRM Institute of Science and Technology, Kattankulathur Campus, 603 203, Tamilnadu, India
| | - Shubing Zhang
- Department of Cell Biology, School of Life Sciences, Central South University, Changsha, Hunan, 410013, PR China
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Pesticide Pollution: Detrimental Outcomes and Possible Mechanisms of Fish Exposure to Common Organophosphates and Triazines. J Xenobiot 2022; 12:236-265. [PMID: 36135714 PMCID: PMC9500960 DOI: 10.3390/jox12030018] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 08/28/2022] [Accepted: 08/29/2022] [Indexed: 11/16/2022] Open
Abstract
Pesticides are well known for their high levels of persistence and ubiquity in the environment, and because of their capacity to bioaccumulate and disrupt the food chain, they pose a risk to animals and humans. With a focus on organophosphate and triazine pesticides, the present review aims to describe the current state of knowledge regarding spatial distribution, bioaccumulation, and mode of action of frequently used pesticides. We discuss the processes by which pesticides and their active residues are accumulated and bioconcentrated in fish, as well as the toxic mechanisms involved, including biological redox activity, immunotoxicity, neuroendocrine disorders, and cytotoxicity, which is manifested in oxidative stress, lysosomal and mitochondrial damage, inflammation, and apoptosis/autophagy. We also explore potential research strategies to close the gaps in our understanding of the toxicity and environmental risk assessment of organophosphate and triazine pesticides.
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Thambirajah AA, Wade MG, Verreault J, Buisine N, Alves VA, Langlois VS, Helbing CC. Disruption by stealth - Interference of endocrine disrupting chemicals on hormonal crosstalk with thyroid axis function in humans and other animals. ENVIRONMENTAL RESEARCH 2022; 203:111906. [PMID: 34418447 DOI: 10.1016/j.envres.2021.111906] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 08/04/2021] [Accepted: 08/16/2021] [Indexed: 06/13/2023]
Abstract
Thyroid hormones (THs) are important regulators of growth, development, and homeostasis of all vertebrates. There are many environmental contaminants that are known to disrupt TH action, yet their mechanisms are only partially understood. While the effects of Endocrine Disrupting Chemicals (EDCs) are mostly studied as "hormone system silos", the present critical review highlights the complexity of EDCs interfering with TH function through their interactions with other hormonal axes involved in reproduction, stress, and energy metabolism. The impact of EDCs on components that are shared between hormone signaling pathways or intersect between pathways can thus extend beyond the molecular ramifications to cellular, physiological, behavioral, and whole-body consequences for exposed organisms. The comparatively more extensive studies conducted in mammalian models provides encouraging support for expanded investigation and highlight the paucity of data generated in other non-mammalian vertebrate classes. As greater genomics-based resources become available across vertebrate classes, better identification and delineation of EDC effects, modes of action, and identification of effective biomarkers suitable for HPT disruption is possible. EDC-derived effects are likely to cascade into a plurality of physiological effects far more complex than the few variables tested within any research studies. The field should move towards understanding a system of hormonal systems' interactions rather than maintaining hormone system silos.
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Affiliation(s)
- Anita A Thambirajah
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, V8P 5C2, Canada
| | - Michael G Wade
- Environmental Health Science & Research Bureau, Health Canada, Ottawa, ON, K1A 0K9, Canada
| | - Jonathan Verreault
- Centre de Recherche en Toxicologie de l'environnement (TOXEN), Département des Sciences Biologiques, Université du Québec à Montréal, Succursale Centre-ville, Montréal, QC, H3C 3P8, Canada
| | - Nicolas Buisine
- UMR7221 Physiologie Moléculaire et Adaptation, Centre National de la Recherche Scientifique, Muséum National d'Histoire Naturelle, Paris Cedex 05, France
| | - Verônica A Alves
- Centre Eau Terre Environnement, Institut National de La Recherche Scientifique (INRS), Québec City, QC, G1K 9A9, Canada
| | - Valerie S Langlois
- Centre Eau Terre Environnement, Institut National de La Recherche Scientifique (INRS), Québec City, QC, G1K 9A9, Canada
| | - Caren C Helbing
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, V8P 5C2, Canada.
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Korkmaz N, Örün İ. Effects of pesticide NeemAzal-T/S on thyroid, stress hormone and some cytokines levels in freshwater common carp, Cyprinus carpio L. TOXIN REV 2021. [DOI: 10.1080/15569543.2021.1895841] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Nuh Korkmaz
- Department of Biology, Faculty of Arts and Sciences, Osmaniye Korkut Ata University, Osmaniye, Turkey
| | - İbrahim Örün
- Department of Biology, Faculty of Science and Letters, Aksaray University, Aksaray, Turkey
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Hernández AF, Bennekou SH, Hart A, Mohimont L, Wolterink G. Mechanisms underlying disruptive effects of pesticides on the thyroid function. CURRENT OPINION IN TOXICOLOGY 2020. [DOI: 10.1016/j.cotox.2019.10.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Leemans M, Couderq S, Demeneix B, Fini JB. Pesticides With Potential Thyroid Hormone-Disrupting Effects: A Review of Recent Data. Front Endocrinol (Lausanne) 2019; 10:743. [PMID: 31920955 PMCID: PMC6915086 DOI: 10.3389/fendo.2019.00743] [Citation(s) in RCA: 103] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 10/14/2019] [Indexed: 12/26/2022] Open
Abstract
Plant Protection Products, more commonly referred to as pesticides and biocides, are used to control a wide range of yield-reducing pests including insects, fungi, nematodes, and weeds. Concern has been raised that some pesticides may act as endocrine disrupting chemicals (EDCs) with the potential to interfere with the hormone systems of non-target invertebrates and vertebrates, including humans. EDCs act at low doses and particularly vulnerable periods of exposure include pre- and perinatal development. Of critical concern is the number of pesticides with the potential to interfere with the developing nervous system and brain, notably with thyroid hormone signaling. Across vertebrates, thyroid hormone orchestrates metamorphosis, brain development, and metabolism. Pesticide action on thyroid homeostasis can involve interference with TH production and its control, displacement from distributor proteins and liver metabolism. Here we focused on thyroid endpoints for each of the different classes of pesticides reviewing epidemiological and experimental studies carried out both in in vivo and in vitro. We conclude first, that many pesticides were placed on the market with insufficient testing, other than acute or chronic toxicity, and second, that thyroid-specific endpoints for neurodevelopmental effects and mixture assessment are largely absent from regulatory directives.
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Affiliation(s)
- Michelle Leemans
- Muséum National d'Histoire Naturelle, CNRS UMR 7221, Laboratoire Physiologie moléculaire de l'adaptation, Paris, France
| | | | | | - Jean-Baptiste Fini
- Muséum National d'Histoire Naturelle, CNRS UMR 7221, Laboratoire Physiologie moléculaire de l'adaptation, Paris, France
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Mulder TA, van den Dries MA, Korevaar TIM, Ferguson KK, Peeters RP, Tiemeier H. Organophosphate pesticides exposure in pregnant women and maternal and cord blood thyroid hormone concentrations. ENVIRONMENT INTERNATIONAL 2019; 132:105124. [PMID: 31479957 PMCID: PMC6827719 DOI: 10.1016/j.envint.2019.105124] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 08/21/2019] [Accepted: 08/23/2019] [Indexed: 05/17/2023]
Abstract
BACKGROUND Animal studies suggest that organophosphate (OP) pesticides exposure affects thyroid function, but evidence in humans remains sparse and inconclusive. Gestational exposure is of particular interest, since thyroid hormone is essential for fetal brain development. OP pesticides are able to cross the placental and blood-brain barrier and may interfere with fetal development processes regulated by thyroid hormone. OBJECTIVE To investigate the association of gestational OP pesticides exposure during pregnancy with maternal and cord blood thyroid hormone concentrations. METHODS This study was embedded within Generation R (Rotterdam, the Netherlands), a prospective population-based birth cohort. Mother-child pairs with OP pesticides assessment and maternal (N = 715) or cord blood (N = 482) thyroid hormone measurements were included. OP pesticides exposure was assessed at <18, 18-25, and >25 weeks gestation by measuring six urinary dialkylphosphate (DAP) metabolites. Thyroid stimulating hormone (TSH) and free thyroxine (FT4) were measured in maternal and cord blood. Maternal measures also included total thyroxine (TT4) and TPO antibodies (TPOAbs). To study the association of creatinine-adjusted DAP metabolite concentrations with thyroid function and TPO antibodies, multivariable linear regression models including relevant confounders were used. RESULTS There was no association of DAP metabolites with maternal TSH, FT4, TT4 or TPOAb concentrations during pregnancy. Similarly, there was no association of DAP metabolites with cord blood TSH or FT4. Results did not change when DAP concentrations were analyzed at individual time points or as mean gestational exposure. CONCLUSION Gestational OP pesticides exposure, as assessed by repeatedly measured urinary DAP metabolite concentrations in an urban population, was not associated with maternal or cord blood thyroid hormone concentrations. These findings do not support a mediating role for serum thyroid hormone availability in the relation of early life exposure to low levels of OP pesticides with child neurodevelopment. However, disruption of the thyroid system at tissue level cannot be excluded. In addition, this is one of the first studies on this subject and measurement error in DAP metabolites might have resulted in imprecise estimates. Future studies should use more urine samples to increase precision and should investigate specific OP pesticide metabolites.
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Affiliation(s)
- Tessa A Mulder
- Generation R Study Group, Erasmus University Medical Center, Rotterdam, the Netherlands; Department of Internal Medicine, Academic Center for Thyroid Diseases, Erasmus University Medical Center, Rotterdam, the Netherlands; Department of Child and Adolescent Psychiatry, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Michiel A van den Dries
- Generation R Study Group, Erasmus University Medical Center, Rotterdam, the Netherlands; Department of Child and Adolescent Psychiatry, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Tim I M Korevaar
- Department of Internal Medicine, Academic Center for Thyroid Diseases, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Kelly K Ferguson
- Epidemiology Branch, Division of Intramural Research, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA
| | - Robin P Peeters
- Department of Internal Medicine, Academic Center for Thyroid Diseases, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Henning Tiemeier
- Department of Child and Adolescent Psychiatry, Erasmus University Medical Center, Rotterdam, the Netherlands; Department of Social and Behavioral Science, Harvard TH Chan School of Public Health, Boston, USA.
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Yue Z, Yu M, Zhang X, Dong Y, Tian H, Wang W, Ru S. Semicarbazide-induced thyroid disruption in Japanese flounder (Paralichthys olivaceus) and its potential mechanisms. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2017; 140:131-140. [PMID: 28254723 DOI: 10.1016/j.ecoenv.2017.02.043] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 02/23/2017] [Accepted: 02/24/2017] [Indexed: 06/06/2023]
Abstract
Semicarbazide (SMC) is a carcinogenic and genotoxic substance that has been found in aquatic systems. SMC may also cause thyroid follicular epithelial cell injury in rats, but the thyroid-disrupting properties of SMC and its potential mechanisms remain unclear. In this study, we exposed fertilized eggs of Japanese flounder (Paralichthys olivaceus) to 1, 10, 100, and 1000μg/L SMC for 55 d to assess the impact of SMC exposure on the thyroid system. The number of larvae in each metamorphic stage was counted, the concentrations of whole-body thyroid hormones (THs) 3,5,3'-triiodothyronine (T3) and thyroxine (T4) were measured, and the transcription levels of genes involved in the hypothalamic-pituitary-thyroid (HPT) axis and gamma-aminobutyric acid (GABA) synthesis were quantified. The results showed that 10μg/L SMC significantly increased whole-body T3 levels, and 100 and 1000μg/L SMC markedly enhanced whole-body T4 and T3 levels. Furthermore, 100μg/L SMC exposure shortened the time it took for flounder larvae to complete metamorphosis by 2 d as compared to the control group. Thus, this study demonstrated that SMC exerted thyroid-disrupting effects on Japanese flounder. SMC-mediated stimulation of TH levels was primarily related to transcriptional alterations of pituitary-derived thyroid stimulating hormone β-subunit (tshβ) and hepatic deiodinase (id). In the 10 and 100μg/L SMC exposure groups, the increased TH levels may have resulted from inhibition of TH metabolism caused by down-regulation of id3 mRNA expression, while at 1000μg/L SMC-exposed group, up-regulation of tshβ and id1 transcripts was expected to enhance the synthesis of T4 and the conversion of T4 to T3 and, consequently, result in higher T4 and T3 levels. In addition, 1000μg/L SMC-induced down-regulation in glutamic acid decarboxylase gad65 and gad67 transcription may have also contributed to the increased TH levels. The thyroid-disrupting effects of 10 and 100μg/L SMC indicated that environmentally relevant concentrations of SMC posed potential environmental risks to aquatic organisms. Overall, our results demonstrated for the first time that SMC exhibited thyroid-disrupting properties by affecting the HPT axis and GABA synthesis, providing theoretical support for environmental risk assessment.
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Affiliation(s)
- Zonghao Yue
- Marine Life Science College, Ocean University of China, Qingdao 266003, China
| | - Miao Yu
- Marine Life Science College, Ocean University of China, Qingdao 266003, China
| | - Xiaona Zhang
- Marine Life Science College, Ocean University of China, Qingdao 266003, China
| | - Yifei Dong
- Marine Life Science College, Ocean University of China, Qingdao 266003, China
| | - Hua Tian
- Marine Life Science College, Ocean University of China, Qingdao 266003, China
| | - Wei Wang
- Marine Life Science College, Ocean University of China, Qingdao 266003, China
| | - Shaoguo Ru
- Marine Life Science College, Ocean University of China, Qingdao 266003, China.
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Gong Y, Tian H, Dong Y, Zhang X, Wang W, Ru S. An in vivo assay performed using multiple biomarkers related to testosterone synthesis and conversion for assessing the androgenic potency of refuse leachate. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2017; 135:82-89. [PMID: 27716536 DOI: 10.1016/j.ecoenv.2016.09.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 09/19/2016] [Accepted: 09/23/2016] [Indexed: 06/06/2023]
Abstract
Refuse leachate is likely an important source of androgens. However, common in vitro bioassays underestimate the potential androgenic activity of leachate, owing to non-receptor-mediated mechanisms that modify the balance of sex hormones and promote the accumulation of endogenous androgens. This study aimed to develop an in vivo assay by using multiple biomarkers related to testosterone synthesis and conversion for assessing the potential androgenic activity of refuse leachate sampled from a municipal solid waste treatment plant in Qingdao, China. The results indicated that exposure to leachate increased the levels of testosterone and luteinizing hormone, but decreased those of 17β-estradiol in both male and female goldfish (Carassius auratus), suggesting a potential androgenic activity. Further, Leydig cell hyperplasia and decreased gonadal P450 aromatase mRNA levels were observed; these alterations might promote the biosynthesis of testosterone and hinder the conversion of testosterone to 17β-estradiol, which in turn enhance testosterone accumulation. Exposure to leachate also resulted in reproductive impairments, including decreased gonadosomatic index and plasma vitellogenin levels of female goldfish, as well as decreased testicular enzyme activities in male goldfish. The integrated use of biochemical, molecular, and histological markers not only improved our understanding of the androgenic effects of leachate but also verified the reliability and validity of the results. Therefore, the in vivo bioassay described in this study might allow the investigation of the androgenic effects of other complex contaminant mixtures in the future.
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Affiliation(s)
- Yufeng Gong
- Marine Life Science College, Ocean University of China, Qingdao 266003, China
| | - Hua Tian
- Marine Life Science College, Ocean University of China, Qingdao 266003, China
| | - Yifei Dong
- Marine Life Science College, Ocean University of China, Qingdao 266003, China
| | - Xiaona Zhang
- Marine Life Science College, Ocean University of China, Qingdao 266003, China
| | - Wei Wang
- Marine Life Science College, Ocean University of China, Qingdao 266003, China.
| | - Shaoguo Ru
- Marine Life Science College, Ocean University of China, Qingdao 266003, China.
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Gong Y, Tian H, Zhang X, Dong Y, Wang W, Ru S. Refuse leachate exposure causes changes of thyroid hormone level and related gene expression in female goldfish (Carassius auratus). ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2016; 48:46-52. [PMID: 27736670 DOI: 10.1016/j.etap.2016.10.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 10/02/2016] [Accepted: 10/04/2016] [Indexed: 06/06/2023]
Abstract
To elucidate the potential thyroid disrupting effects of refuse leachate on females, female goldfish (Carassius auratus) were exposed to 0.5% diluted leachates from each step of a leachate treatment process (i.e. raw leachate before treatment, after membrane bioreactor treatment, and the final treated leachate) for 21days. Raw leachate exposure caused disturbances in the thyroid cascade of female fish, as evidenced by the elevated plasma 3,3',5-triiodo-l-thyronine (p<0.05) and thyroid-stimulating hormone (p<0.01) levels as well as up-regulated hepatic and gonadal type I deiodinase (p<0.01), type II deiodinase (p<0.01) and thyroid receptor (p<0.05) mRNA levels. Thyroid disrupting potency decreased markedly as raw leachate progressed through the "membrane bioreactor + reverse osmosis" treatment but could still be detected in the treated leachate. As our results indicated, thyroid system in female goldfish was more sensitive to leachate exposure than that of the male fish.
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Affiliation(s)
- Yufeng Gong
- Marine Life Science College, Ocean University of China, Qingdao, 266003, China
| | - Hua Tian
- Marine Life Science College, Ocean University of China, Qingdao, 266003, China
| | - Xiaona Zhang
- Marine Life Science College, Ocean University of China, Qingdao, 266003, China
| | - Yifei Dong
- Marine Life Science College, Ocean University of China, Qingdao, 266003, China
| | - Wei Wang
- Marine Life Science College, Ocean University of China, Qingdao, 266003, China
| | - Shaoguo Ru
- Marine Life Science College, Ocean University of China, Qingdao, 266003, China.
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Yu M, Zhang X, Guo L, Tian H, Wang W, Ru S. Anti-estrogenic effect of semicarbazide in female zebrafish (Danio rerio) and its potential mechanisms. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2016; 170:262-270. [PMID: 26688189 DOI: 10.1016/j.aquatox.2015.11.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 11/25/2015] [Accepted: 11/26/2015] [Indexed: 06/05/2023]
Abstract
Semicarbazide (SMC), a member of the hydrazine family, has various toxic effects and has been detected in organisms, aquatic environments, and food. SMC exposure inhibited the transcription of hepatic vitellogenin and estrogen receptors in female zebrafish (Danio rerio), suggesting that it had anti-estrogenic properties. In order to elucidate the mechanisms underlying these, we exposed female zebrafish to SMC and used enzyme-linked immunosorbent assays to examine plasma 17β-estradiol (E2) and testosterone (T) levels. Gonad histology was analyzed and the mRNA expression of genes involved in the reproductive axis, the gamma-aminobutyric acid (GABA) shunt, and leptin was quantified by real-time PCR. Zebrafish were exposed to 1, 10, 100, or 1000μg/L SMC in a semi-static system for 96hours or 28 days. Plasma E2 levels were significantly decreased and ovarian maturation was inhibited by SMC, suggesting that its anti-estrogenic effect was exerted by reducing endogenous E2 levels. This was likely due to the SMC-mediated inhibition of cytochrome P450 (CYP) 19A mRNA levels, because this enzyme catalyzes the conversion of T to E2 in the gonads. In addition, down-regulation of the mRNA expression of 3-hydroxy-3-methylglutaryl coenzyme A reductase, steroidogenic acute regulatory protein, CYP17, and 17beta-hydroxysteroid dehydrogenase was observed; this was predicted to reduce T concentrations and further contribute to the reduced E2 levels. SMC-induced changes in the expression of these steroidogenic genes correlated with decreased transcription of gonadotropic hormones (follicle-stimulating hormone and luteinizing hormone) and significantly elevated leptin expression. Furthermore, SMC also altered expression of the key enzyme in gamma-aminobutyric acid (GABA) synthesis, GABA receptors, and salmon gonadotropin-releasing hormone, thus affecting gonadotropin expression. Overall, SMC acted at multiple sites related to reproduction to reduce plasma E2 levels, consequently exerting an anti-estrogenic effect in female zebrafish. These effects were observed at environmentally relevant concentrations and highlight the importance of controlling SMC contamination.
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Affiliation(s)
- Miao Yu
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
| | - Xiaona Zhang
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
| | - Linlin Guo
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
| | - Hua Tian
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
| | - Wei Wang
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China
| | - Shaoguo Ru
- College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
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