Larval exposure to environmentally relevant concentrations of triclosan impairs metamorphosis and reproductive fitness in zebrafish

Stenzel, Amanda; Wirt, Heidi; Patten, Alyssa; Theodore, Briannae; King‐Heiden, Tisha C.

doi:10.1016/j.reprotox.2019.05.055

Cited by 27 publications

(17 citation statements)

References 88 publications

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“…Similar to our results, one study found that TCS exposure delayed the hatching of 6-13 h in medaka fish (28). A recent study found that the offspring of zebrafish exposed to TCS decreased the survival rate and delayed maturation (50), which might be partially explained by decreased thyroid hormone resulting from TCS exposure (50). The adverse effect of longterm exposure to TCS on thyroid hormone levels might be due to the cumulative effect of TCS on the development of zebrafish thyroid glands.…”

Section: Discussionsupporting

confidence: 89%

The Effect of Early Life Exposure to Triclosan on Thyroid Follicles and Hormone Levels in Zebrafish

Fan

Chen

et al. 2022

Front. Endocrinol.

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Triclosan (TCS) is an antimicrobial chemical widely used in personal care products. Most of the TCS component is discharged and enters the aquatic ecosystem after usage. TCS has a similar structure as thyroid hormones that are synthesized by thyroid follicular epithelial cells, thus TCS has a potential endocrine disrupting effect. It is still not clear how the different levels of the environmental TCS would affect early development in vivo. This study examines the effects of TCS on thyroid hormone secretion and the early development of zebrafish. The fertilized zebrafish eggs were exposed to TCS at 0 (control), 3, 30, 100, 300, and 900 ng/mL, and the hatching rate and the larvae mortality were inspected within the first 14 days. The total triiodothyronine (TT3), total thyroxine (TT4), free triiodothyronine (FT3), and free thyroxine (FT4) were measured at 7, 14, and 120 days post-fertilization (dpf). The histopathological examinations of thyroid follicles were conducted at 120 dpf. TCS exposure at 30-300 ng/mL reduced the hatching rate of larvae to 34.5% to 28.2 % in the first 48 hours and 93.8 .7 % to 86.8 % at 72 h. Extremely high TCS exposure (900 ng/mL) strongly inhibited the hatching rate, and all the larvae died within 1 day. Exposure to TCS from 3 to 300 ng/mL reduced the thyroid hormones production. The mean TT3 and FT3 levels of zebrafish decreased in 300 ng/mL TCS at 14 dpf (300 ng/mL TCS vs. control : TT3 , 0.19 ± 0.08 vs. 0.39 ± 0.06; FT3, 19.21 ± 3.13 vs. 28.53 ± 1.98 pg/mg), and the FT4 decreased at 120 dpf ( 0.09 ± 0.04 vs. 0.20 ± 0.14 pg/mg). At 120 dpf , in the 300 ng/mL TCS exposure group, the nuclear area and the height of thyroid follicular epithelial cells became greater, and the follicle cell layer got thicker. This happened along with follicle hyperplasia, nuclear hypertrophy, and angiogenesis in the thyroid. Our study demonstrated that early life exposure to high TCS levels reduces the rate and speed of embryos hatching, and induces the histopathological change of thyroid follicle, and decreases the TT3, FT3, and FT4 production in zebrafish.

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Section: Discussionsupporting

confidence: 89%

The Effect of Early Life Exposure to Triclosan on Thyroid Follicles and Hormone Levels in Zebrafish

Fan

Chen

et al. 2022

Front. Endocrinol.

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“…The other study found that sub-chronic (21 days) exposure to 100 μg/g TCS caused hyperplasia of thyroid follicle in adult zebrafish [11] . A recent study [48] found that offspring of zebrafish that exposed to TCS decreased survival rate and delayed maturation. This can be explained by decreased thyroid hormone resulting from TCS exposure.…”

Section: Discussionmentioning

confidence: 99%

Early life Exposure to Triclosan Impacted Thyroid Follicular Structure and Decreased Thyroid Hormone Levels in Zebrafish

Tang¹,

Fan²,

Yu³

et al. 2020

Preprint

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Background: Triclosan (TCS) is an antimicrobial chemical widely used in personal care products. Most of TCS is discharged into aquatic ecosystem after usage. While TCS has potential thyroid-disrupting effect, it is unknown whether early exposure to TCS affects thyroid grand and thyroid hormone levels. We used zebrafish model to examine this topic.Methods: The fertilized zebrafish eggs were exposed to TCS. We inspected hatching and mortality of larvae. The total triiodothyronine (TT3), total thyroxine (TT4), free triiodothyronine (FT3), and free thyroxine (FT4) levels were measured at 7, 14 and 120 days post fertilization (dpf). Thyroid histopathological analysis was conducted at 120 dpf of zebrafish.Results: The hatching rate of embryos decreased from 95.8% in control group to 18.3% in TCS highest exposure in 3 days. In 900 ng/mL TCS exposure all larvae died within one day. With increasing concentration of TCS exposure, TT3 and FT3 level decreased after 14 days. FT4 decreased, and the height and nuclear area of thyroid follicular cell increased with TCS exposure after 120 days.Conclusions: High TCS exposure decreased the hatching rate of zebrafish embryos, and also decreased thyroid hormone levels owing to structural change of thyroid follicles. Our study raised the concern that TCS exposure in early life may profoundly affect neurodevelopment.

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“…Their adverse effects leading to certain forms of cancers and other non-communicable diseases such as diabetes in man (Diamanti-Kandarakis et al 2009 ; Lyche et al 2011 ) and adverse effect on the population of aquatic lives (Jobling et al 2002 ; Diao et al 2017 ) have been reported. The exposure of zebrafish larvae to ED such as triclosan at environmentally relevant concentrations delayed metamorphosis, impaired fecundity and fertility presumed to be related to altered thyroid hormone homeostasis (Stenzel et al 2019 ).…”

Section: Introductionmentioning

confidence: 99%

Determination and ecological risk assessment of two endocrine disruptors from River Buffalo, South Africa

Olaniyan

Okoh

2020

Environ Monit Assess

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4-tert-Octylphenol (4-tOP) and triclosan (TCS) are endocrine disruptors which have been detected in environmental matrices such as air, soil and water at ultra-low levels. Exposure to endocrine disruptors may account at least in part, for the global increase in the incidence of non-communicable diseases like cancers and diabetes and may also lead to an imbalance in the aquatic ecosystem. River Buffalo is an important natural resource in the Eastern Cape of South Africa serving more than half a million people. The presence of the two compounds in the river water hitherto unknown was investigated during winter seasons using solid-phase extraction and gas chromatography–mass spectrometric techniques. The sampling points differed by some physicochemical parameters. The concentration of 4-tOP ranged 0–755 ng/L, median value 88.1 ng/L while that of TCS ranged 0–1264.2 ng/L and the median value was 82.1 ng/L. Hazard quotient as an index of exposure risk varied according to daphnids ˃ fish ˃ algae for 4-tOP exposure while HQ for TCS exposure was algae > daphnids = fish showing that both compounds were capable of causing imbalance in the aquatic ecosystem.

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Larval exposure to environmentally relevant concentrations of triclosan impairs metamorphosis and reproductive fitness in zebrafish

Cited by 27 publications

References 88 publications

The Effect of Early Life Exposure to Triclosan on Thyroid Follicles and Hormone Levels in Zebrafish

The Effect of Early Life Exposure to Triclosan on Thyroid Follicles and Hormone Levels in Zebrafish

Early life Exposure to Triclosan Impacted Thyroid Follicular Structure and Decreased Thyroid Hormone Levels in Zebrafish

Determination and ecological risk assessment of two endocrine disruptors from River Buffalo, South Africa

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