The effect of mercuric chloride on thyroid function in the rat

Goldman, Max; Blackburn, Paul

doi:10.1016/s0041-008x(79)80007-1

Cited by 21 publications

(4 citation statements)

References 21 publications

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“…According to Fort et al [34], increased tail resorption time due to toxicant exposure is frequently mediated through inhibition of the thyroid axis. Changes in thyroid function due to Hg exposure have been demonstrated in fish [35], rodents [36, 37], and humans [38]. Decreases in tail resorption rate observed in this experiment suggest that Hg may also inhibit the amphibian thyroid axis.…”

Section: Discussionmentioning

confidence: 56%

Adverse effects of ecologically relevant dietary mercury exposure in southern leopard frog (Rana sphenocephala) larvae

Unrine

Jagoe

Hopkins

et al. 2004

Enviro Toxic and Chemistry

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Southern leopard frog (Rana sphenocephala) larvae were exposed to experimental diets supplemented with aufwuchs from control and mercury-enriched mesocosms combined in proportions intended to mimic mercury concentrations and speciation in aufwuchs observed from aquatic systems contaminated by atmospheric deposition. Observations on rates of mortality, malformation, and larval growth and development were made for 254 d. Increased incidence of mortality, malformation, and changes in growth and development were observed at concentrations that reflect the highest concentrations expected in the amphibian diet from atmospheric deposition (1,500-3,300 ng Hg/g dry wt). The results of this study are probably more ecologically realistic than results obtained from previous studies of aqueous mercury toxicity and suggest that dietary mercury exposure in habitats contaminated primarily by atmospheric deposition has the potential to cause adverse effects in amphibian larvae.

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Section: Discussionmentioning

confidence: 56%

Adverse effects of ecologically relevant dietary mercury exposure in southern leopard frog (Rana sphenocephala) larvae

Unrine

Jagoe

Hopkins

et al. 2004

Enviro Toxic and Chemistry

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“…In both cases, ingestion of methylmercury (MeHg)-tainted fish or grains led to neurological damage and death of both humans and wild animals. Increasing evidence suggests that Hg can act as an endocrine disruptor as well. − Mercury is known to accumulate in endocrine organs, prevent steroidogenesis, and lead to abnormal levels of sex hormones, glucocorticoids, and thyroid hormones . However, the direct mechanistic link between Hg, its effects on hormone disruption, and any subsequent effects on development or survival has not been examined in depth.…”

Section: Introductionmentioning

confidence: 99%

Dietary Mercury Has No Observable Effects on Thyroid-Mediated Processes and Fitness-Related Traits in Wood Frogs

Wada

Bergeron

McNabb

et al. 2011

Environ. Sci. Technol.

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Mercury (Hg) is a neurotoxicant known to cause developmental and behavioral abnormalities in vertebrates. Increasing evidence suggests that Hg can also disrupt endocrine functions and endocrine-dependent processes. For example, dietary Hg has been shown to delay tail resorption during metamorphic climax in amphibians, a process mediated by thyroid hormones. However, a direct link between Hg, hormone disruption, and developmental delays in amphibians has not been explored. Therefore, we examined the effects of dietary Hg (0.01, 2.5, and 10 μg/g total Hg, dry wt) on thyroid hormone concentrations, development, growth, performance, and survival of wood frogs (Rana sylvatica). Tadpoles accumulated Hg in a concentration-dependent manner; total Hg concentrations in tadpoles at the beginning of metamorphic climax (Gosner stage 42) were 0.03, 1.06, 3.54 μg/g, dry wt, for control, low, and high Hg diets, respectively. During metamorphic climax, tadpoles eliminated 35% of the inorganic Hg from their tissues but retained most of their accumulated methylmercury. Contrary to our predictions, we found no effect of Hg on the duration of tadpole development, size at metamorphosis, tail resorption time, or hopping performance. Consistent with the lack of effects on development, we also detected no differences in whole-body thyroid hormone concentrations among our dietary treatments. Our results, when compared with the effects of Hg on other amphibians, suggest that amphibian species may differ substantially in their sensitivity to dietary Hg, emphasizing the need for data on multiple species when establishing toxicity benchmarks.

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“…Adult rats orally exposed to HgCl 2 have reduced locomotor activity and gait disturbances (Goldman & Blackburn, 1979;Teixeira et al, 2014). At the highest wAAT tested HgCl 2 exposure of 100 μg/mL, there was only hypoactivity, indicating that higher levels of toxicity can overwhelm the escape response in C. elegans and that hypoactivity is a concordant effect of exposure to high levels of inorganic mercury.…”

Section: Discussionmentioning

confidence: 99%

“…We hypothesize that this initial hyperactivity phase in the presence of a toxicant that later induces hypoactivity is an escape response that, in a natural habitat, supports the organism moving to a less toxic environment. Adult rats orally exposed to HgCl 2 have reduced locomotor activity and gait disturbances (Goldman & Blackburn, 1979; Teixeira et al, 2014). At the highest wAAT tested HgCl 2 exposure of 100 μg/mL, there was only hypoactivity, indicating that higher levels of toxicity can overwhelm the escape response in C. elegans and that hypoactivity is a concordant effect of exposure to high levels of inorganic mercury.…”

Section: Discussionmentioning

confidence: 99%

The worm Adult Activity Test (wAAT): A de novo mathematical model for detecting acute chemical effects in Caenorhabditis elegans

Hunt

Welch

Camacho

et al. 2023

J of Applied Toxicology

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We have adapted a semiautomated method for tracking Caenorhabditis elegans spontaneous locomotor activity into a quantifiable assay by developing a sophisticated method for analyzing the time course of measured activity. The 16‐h worm Adult Activity Test (wAAT) can be used to measure C. elegans activity levels for efficient screening for pharmacological and toxicity‐induced effects. As with any apical endpoint assay, the wAAT is mode of action agnostic, allowing for detection of effects from a broad spectrum of response pathways. With caffeine as a model mild stimulant, the wAAT showed transient hyperactivity followed by reversion to baseline. Mercury chloride (HgCl2) produced an early dose–response hyperactivity phase followed by pronounced hypoactivity, a behavior pattern we have termed a toxicant “escape response.” Methylmercury chloride (meHgCl) produced a similar pattern to HgCl2, but at much lower concentrations, a weaker hyperactivity response, and more pronounced hypoactivity. Sodium arsenite (NaAsO2) and dimethylarsinic acid (DMA) induced hypoactivity at high concentrations. Acute toxicity, as measured by hypoactivity in C. elegans adults, was ranked: meHgCl > HgCl2 > NaAsO2 = DMA. Caffeine was not toxic with the wAAT at tested concentrations. Methods for conducting the wAAT are described, along with instructions for preparing C. elegans Habitation Medium, a liquid nutrient medium that allows for developmental timing equivalent to that found with C. elegans grown on agar with OP50 Escherichia coli feeder cultures. A de novo mathematical parametric model for adult C. elegans activity and the application of this model in ranking exposure toxicity are presented.

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The effect of mercuric chloride on thyroid function in the rat

Cited by 21 publications

References 21 publications

Adverse effects of ecologically relevant dietary mercury exposure in southern leopard frog (Rana sphenocephala) larvae

Adverse effects of ecologically relevant dietary mercury exposure in southern leopard frog (Rana sphenocephala) larvae

Dietary Mercury Has No Observable Effects on Thyroid-Mediated Processes and Fitness-Related Traits in Wood Frogs

The worm Adult Activity Test (wAAT): A de novo mathematical model for detecting acute chemical effects in Caenorhabditis elegans

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