Endocrine disruptive potential of endosulfan on the reproductive axis of Cichlasoma dimerus (Perciformes, Cichlidae) (original) (raw)
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Comparative biochemistry and physiology. Toxicology & pharmacology : CBP, 2016
The organochlorine pesticide endosulfan (ES) is used in several countries as a wide spectrum insecticide on crops with high commercial value. Due to its high toxicity to non-target animals, its persistence in the environment and its ability to act as an endocrine disrupting compound in fish, ES use is currently banned or restricted in many other countries. Previous studies on the cichlid fish Cichlasoma dimerus have shown that waterborne exposure to ES can lead to both decreased pituitary FSH content and histological alterations of testes. As gonadotropin-stimulated sex steroids release from gonads was inhibited by ES in vitro, the aim of the present study was to elucidate possible mechanisms of disruption of ES on gonadal steroidogenesis in C. dimerus, as well as compare the action of the active ingredient (AI) with that of currently used commercial formulations (CF). Testis and ovary fragments were incubated with ES (AI or CF) and/or steroidogenesis activators or precursors. Testo...
Archives of Environmental Contamination and Toxicology, 2010
Endocrine-disrupting chemicals can influence the hypothalamus-pituitary-gonad axis and possibly affect reproduction in vertebrates. We analyzed the effect of 30day endosulfan (ES) exposure in sexually undifferentiated larvae of the cichlid fish Cichlasoma dimerus. The number, area, mean cytoplasmic and nuclear diameter, and mean cytoplasmic optical density of gonadotropin-releasing hormone (GnRH) I, II, and III immunoreactive (ir-) neurons and b follicle-stimulating hormone (bFSH) ir-cells were measured. Animals exposed to the highest ES concentration (0.1 lg/l) showed a decrease in GnRH I nucleus/cytoplasm area ratio upon exposure. Nuclear area and mean nuclear diameter of bFSH ir-cells was higher in ES treated fish. bFSH nucleus/cytoplasm area ratio was high in exposed animals, and animals exposed to 0.1 lg/l ES showed smaller mean cytoplasmic optical density. These findings suggest that ES affects GnRH I and bFSH protein synthesis/release. However, these responses seem to be insufficient to affect gonadal differentiation at this stage of development.
Ecotoxicology and Environmental Safety, 2015
Endosulfan (ES) is an organochlorine pesticide widely used in agriculture despite its high toxicity towards non-target organisms such as fish. It has been demonstrated that ES can cause negative effects on aquatic animals, including disruption of hormonal systems. However, the alterations produced by this pesticide on the reproductive axis of fish prior to sexual maturity, as well as possible modes of action have hardly been studied. This study aimed at assessing the effect of waterborne exposure to the pesticide ES on the reproductive axis during sexual differentiation of juveniles of the South American freshwater cichlid fish Cichlasoma dimerus. No mortality was observed due to ES subchronic exposure (90 days post-fertilization). Exposure to ES did not affect body weight nor morphometric parameters, indicating that larvae nutritional state was not affected. Timing of sexual differentiation, gonadal morphology and sex ratio were likewise not altered by ES. However, ES acted as an endocrine disrupting chemical in this species as the morphometry of gonadotropin-releasing hormones (GnRH) producing cells was altered. Exposure to ES altered nuclear area, cell area and nucleus/cytoplasm ratio of GnRH II neurons, and cell and nuclear area and diameter of GnRH III neurons. Interestingly, in our previous study, exposure before sex differentiation (30 day exposure) caused no alteration to GnRH II and III, and did alter GnRH I and FSH cells. These alterations could lead to changes in circulating hormone levels, especially when fish are exposed for prolonged periods, ultimately impairing reproductive fitness. C. dimerus juveniles can be an interesting biological model to perform toxicological studies with the intent to assess early disruption endpoints in the reproductive axis during development.
Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology, 2008
A number of man-made chemicals has been shown to mimic endogenous hormones and to induce alterations of reproductive physiology in wild populations. Of particular importance are compounds that mimic estrogens and androgens (and their antagonists), because of their central role in reproductive function. In this study, male and female adult South African clawed toads (Xenopus laevis) were exposed to ethinylestradiol (EE2), tamoxifen (TAM), methyldihydrotestosterone (MDHT) and flutamide (FLU) as (anti)estrogenic and (anti)androgenic model compounds, respectively, at a concentration of 10 − 8 M, and to water from the river Lambro (LAM), a contaminated watercourse from Northern Italy. Potential disrupting effects on reproduction were studied by histological analyses of gonads. The strongest adverse effects were observed in EE2 and LAM exposed males, e.g. tubule mean diameter reduction, spermatogenic nest breakdown and interlobular wall thickening. In both groups, the occurrence of small oocytes within the seminiferous tubules was observed. In TAM and MDHT exposed females slight oocyte atresia and occurrence of spermatogenic nests were observed. In contrast to previous studies addressing the alteration of molecular biomarkers in the same experimental setup, histological analyses of gonads were very sensitive and indicated an adverse effect of water from Lambro River on reproductive physiology of X. laevis.
Risks Induced by Pesticides on Fish Reproduction
Pollution of water resources with agricultural water drainage has a great risk on fish reproduction. Organophosphrous pesticides such as Malathion and dimethaote are frequently used in Egypt due to their highly effectiveness for controlling agriculture pests. These pesticides were found that have endocrine disrupting effect on fish reproduction through lowering sex steroid hormones (estradiol and testosterone). Endocrine disrupting pesticides also have been implicated in the impairment of fish fecundity, semen quality, hatchability and survivability of fishes. Sex steroid hormones, vitellogenin, organosomatic indices and histopathology are considered as biomarker tools used for assessing disrupting effect of pesticides on fish.
Ecotoxicology and Environmental Safety, 2016
Estrogenic chemicals are often detected in the aquatic environment and can negatively affect animal development and reproduction. In teleost fishes, the hormonal regulation during a critical period of larval development has a strong influence on gonadal sex differentiation; thus this process may be affected by the exposure to environmental estrogens. In this study, we first assessed the lethal acute toxicity of the natural estrogen 17β-estradiol (E 2) and the weaker estrogen mimics 4-tert-octylphenol (OP) and 4-nonylphenol (NP) on larval stages of the South American cichlid fish Cichlasoma dimerus. In a further experiment, we analyzed the effects of chronic waterborne exposure to E 2 and OP on gonad development and sex differentiation. Exposure to high concentrations of E 2 had a pronounced feminizing effect directing sex differentiation towards ovarian development, while testis development was inhibited at a lower, environmentally relevant concentration. Among OP-exposed fish, 15-38.5% of the males exhibited testicular oocytes (TOs), a commonly reported biomarker of estrogenic exposure. However, since TOs were also recorded in control males and the proportion of males with TOs was not significantly higher in OP treatments, their occurrence could not be attributed to OP exposure. In addition, TOs did not seem to impair male gonad development and functionality since normal spermatogenesis was observed in testes of OP-treated fish. These results indicate that E 2 occurring in the South American aquatic environment may affect male reproductive development and pose a risk for wild C. dimerus, especially under prolonged exposure, while the effects of weaker xenoestrogens such as OP would be negligible for gonad development in this species. As illustrated by this study, the natural occurrence of TOs indicates that conclusions concerning the causes of this phenomenon must be drawn with care.
Endocrine disrupting mechanisms and effects of pesticides
Arhiv za farmaciju, 2021
Pesticides are important agents that are intentionally introduced into the environment to control various pests and disease carriers, often by killing them. Although pesticides have many important objectives, including protection against crop loss and vector-borne diseases, there are significant concerns over the potential toxicity of pesticides on various organisms, including humans. The frequent use of pesticides in agriculture has led to the long-term exposure of humans to different pesticide residues. Exposure to pesticides has been linked to disturbances in the endocrine system of animals and humans. There are increasing data on the relation between lipophilic pesticides with low biodegradability and changes in reproductive functions and parameters of male and female animals. But more epidemiological and detailed information is necessary on the probability and strength of pesticide exposure-outcome relations regarding endocrine-disrupting effects.
Environmental Biology of Fishes, 1993
Anabas testudineus were treated with non lethal levels of metacid-50 (0.106 ppb) and carbaryl(1.66 ppm) for 90 days covering the pre-spawning and spawning phases of the annual reproductive cycle. The main purpose of the present work was to identify the effects of metacid-50 and carbaryl on the gonado somatic index (GSI) and ovarian and plasma estrogen level. There was no alteration in GSI until 15 days, initiating the inhibition on day 20 which further intensified from 20 to 90 days of exposure. Plasma and ovarian estrogen level significantly increased up to 15 days of exposure followed by a decline till the end of the experiment. It is noteworthy that the effect of pesticides on GSI is reflected in the ovarian estrogen level. This highlights the fact that at short-term exposures the nonlethal levels of pesticides have no inhibitory effect while at long-term exposure, the pesticides have potent inhibitory effect on the reproduction of fish.
Toxicological Sciences, 2009
The vertebrate hypothalamic-pituitary-gonadal (HPG) axis is controlled through various feedback mechanisms that maintain a dynamic homeostasis in the face of changing environmental conditions, including exposure to chemicals. We assessed the effects of prochloraz on HPG axis function in adult fathead minnows (Pimephales promelas) at multiple sampling times during 8-day exposure and 8-day depuration/recovery phases. Consistent with one mechanism of action of prochloraz, inhibition of cytochrome P450 (CYP) 19 aromatase activity, the fungicide depressed ex vivo ovarian production and plasma concentrations of 17b-estradiol (E2) in female fish. At a prochloraz water concentration of 30 mg/l, inhibitory effects on E2 production were transitory and did not persist during the 8-day exposure phase. At 300 mg/l prochloraz, inhibition of E2 production was evident throughout the 8-day exposure but steroid titers recovered within 1 day of cessation of exposure. Compensation or recovery of steroid production in prochloraz-exposed females was accompanied by upregulation of several ovarian genes associated with steroidogenesis, including cyp19a1a, cyp17 (hydroxylase/lyase), cyp11a (cholesterol side-chain cleavage), and follicle-stimulating hormone receptor. In male fathead minnows, the 8-day prochloraz exposure decreased testosterone (T) production, possibly through inhibition of CYP17. However, as for E2 in females, ex vivo testicular production and plasma concentrations of T recovered within 1 day of stopping exposure. Steroidogenic genes upregulated in testis included cyp17 and cyp11a. These studies demonstrate the adaptability of the HPG axis to chemical stress and highlight the need to consider the dynamic nature of the system when developing approaches to assess potential risks of endocrine-active chemicals.
Effect of Endocrine Disruptor Pesticides: A Review
International Journal of …, 2011
Endocrine disrupting chemicals (EDC) are compounds that alter the normal functioning of the endocrine system of both wildlife and humans. A huge number of chemicals have been identified as endocrine disruptors, among them several pesticides. Pesticides are used to kill unwanted organisms in crops, public areas, homes and gardens, and parasites in medicine. Human are exposed to pesticides due to their occupations or through dietary and environmental exposure (water, soil, air). For several years, there have been enquiries about the impact of environmental factors on the occurrence of human pathologies. This paper reviews the current knowledge of the potential impacts of endocrine disruptor pesticides on human health. CN Cl CN Cl Cl Cl Activation of androgen-sensitive cells proliferation [93] M.S: 0.007-25.31 ng/g [92] U.C: 0.007-25.12 ng/g [92] H.S: mean 6 pg/g [85] Chlordane (I) M(g/Mol) = 409.8 pKa = n.a logP: 2.78 Cl Cl Cl Cl Cl Cl Cl Cl Competitive binding to androgen receptors [76] Anti-estrogenic effect, inhibition of estradiol binding [13] M.P: 0-2.7 ng/g lipid [94] B.S: <LOD-0.9 ng/g lipid [95] H.M: 0.02-437 ng/g lipid [79,96-99] FF: 0.1-0.3 ng/L [100] Chlordecone (I) M(g/Mol) = 490.6 pKa = n.a logP: 4.5 O Cl Cl Cl Cl Cl Cl Cl Cl Cl Cl