Examining the evidence that ethylmercury crosses the blood-brain barrier

Kern, Janet K.; Homme, Kristin G.; Geier, Mark R.

doi:10.1016/j.etap.2019.103312

Cited by 22 publications

(15 citation statements)

References 38 publications

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“…Unithiol and succimer have shown limited or no effect on neurotoxicity from ethylmercury when used in humans [13,50,69,85]. Similar to methylmercury this likely reflects dealkylation of ethylmercury to inorganic mercury (Hg þ2 ) in the brain and the inability of unithiol of succimer to cross the blood brain barrier [86,87]. Acetylcysteine has not been evaluated with ethylmercury in humans, but the additional role of increased glutathione production in the brain supports the choice of acetylcysteine [88].…”

Section: Chelation: Choice Of Chelator Depends On the Form Of Mercurymentioning

confidence: 99%

Rethinking treatment of mercury poisoning: the roles of selenium, acetylcysteine, and thiol chelators in the treatment of mercury poisoning: a narrative review

Spiller

Hays

Casavant

2021

Toxicology Communications

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We reevaluate the treatment of mercury poisoning, incorporating recent advances in understanding of mercury toxicity and the mercury:selenium interaction. This review focuses on: 1) the role, limitations and benefits of chelation (Unithiol, succimer and N-Acetylcysteine); 2) the role of selenium supplementation; and 3) how the different forms of mercury are impacted by use of chelation and selenium. Unithiol and succimer produce increases in urinary excretion of mercury and to a lesser degree blood and total body mercury. The primary role of N-acetylcysteine is increasing renal mercury excretion, similar to the thiol-chelators. Additional unique features of acetylcysteine include increased efflux of methylmercury from the brain, and reduced oxidative stress via increased glutathione production. The role of selenium includes: 1) restoration of selenoprotein activity, 2) protection against mitochondrial injury and DNA damage, 3) demethylation of methylmercury, 4) sequestering of mercury via Hg:Se complexes, and 5) redistribution of Hg inside organisms. Selenium may increase blood Hg, via a "sink" effect, causing a redistribution of mercury away from the brain. A combined approach for mercury poisoning treatment was developed focusing on restoration of selenoprotein function, reduction of oxidative stress and increased mercury elimination.

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Section: Chelation: Choice Of Chelator Depends On the Form Of Mercurymentioning

confidence: 99%

Rethinking treatment of mercury poisoning: the roles of selenium, acetylcysteine, and thiol chelators in the treatment of mercury poisoning: a narrative review

Spiller

Hays

Casavant

2021

Toxicology Communications

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“…Despite the prevalence of rising autism, current detection methods and treatment options for this disease are limited [3,5,7]. Although numerous scientific and well-documented studies have shown no direct links between childhood vaccinations and ASD, serious parental concerns remain regarding the safety of vaccination [8,9]. The organomercury compound thimerosal, which has been in use as an antibacterial and antifungal agent in many vaccines and other injectable biological products, is an important part of this debate [10].…”

Section: Regressive Autism (Ra) and Autism Spectrum Disorder (Asd)mentioning

confidence: 99%

“…It was developed in 1927 and was designed to solve the toxicity concerns of elemental mercury and mercuric chloride as a bactericide and fungicide [10,11]. If thimerosal enters the human brain, it may be metabolized or degraded to highly toxic inorganic mercury-containing compounds that can persist for a long time [9]. However, it is not clear if thimerosal can penetrate the blood-brain barrier (BBB) in normal healthy individuals [9,12].…”

Section: Regressive Autism (Ra) and Autism Spectrum Disorder (Asd)mentioning

confidence: 99%

“…If thimerosal enters the human brain, it may be metabolized or degraded to highly toxic inorganic mercury-containing compounds that can persist for a long time [9]. However, it is not clear if thimerosal can penetrate the blood-brain barrier (BBB) in normal healthy individuals [9,12]. As millions of children who receive thimerosal-containing vaccines and other products that contain ethylmercury do not show apparent signs of neurotoxicity, thimerosal risks are probably minimal [13].…”

Section: Regressive Autism (Ra) and Autism Spectrum Disorder (Asd)mentioning

confidence: 99%

“…Thimerosal was also used in the tetanus-toxoid vaccine until very recently, and it is given to individuals of all ages [27]. Additionally, in the US, over half of influenza-vaccine doses (> 75 million annually) still contain thimerosal [9].…”

Section: Role Of Blood-brain Barrier In Development Of Ramentioning

confidence: 99%

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Gender-Dependent Effects of Thimerosal on Human Progenitor Neurons: A Potential Link to Regressive Autism

Goodwin¹,

Shamabadi²,

Pandey³

et al. 2020

aeer

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Regressive Autism [RA] is a subtype of autism spectrum disorder (ASD) that manifests as the loss of previously acquired developmental milestones and skills. Early life dysregulation of neurodevelopment due to exposure to toxic metals has been associated with ASD, but the underlying biological mechanisms by which metals influence neurodevelopment remain unclear. We explored the potential role of thimerosal or ethylmercury on neurite formation and oxytocin receptor (OXTR) modulation in four human-developing neuronal cell lines of male and female origin (N = 2 each). We exposed the cell lines to three levels of thimerosal that closely represented the concentrations an infant (equivalent to 1 L of blood volume), an adolescent (~5 L), and an adult (~10 L) might receive from multiple doses of vaccine containing 100 µg/mL of thimerosal. We found that exposure to vaccine-equivalent concentrations of thimerosal induced significantly greater neurite dysregulation, including central chromatolysis, neurite abnormalities (i.e., axonal length, relative diameter, and pathways in neurons), and syncytia formation in undifferentiated and partially differentiated human developing neurons compared to controls. Exposure of male neurons to thimerosal significantly affected neurite formation and OXTR expression compared to the female neurons. In developed nations, most vaccines are thimerosal-free; nonetheless, some still incorporate ethylmercury as a preservative. In contrast, due to the lack of refrigeration in many developing nations, thimerosal is still used widely in most vaccines. Our study shows that ethylmercury induced profound neurite dysregulation and downregulated OXTR expression. The progenitor neurons from males were significantly more susceptible to thimerosal than those from females. However, internal factors in vaccine recipients may trigger dysfunction in the Blood-Brain Barrier (BBB), and screening potentially vulnerable individuals for conditions that may contribute to a BBB breach before vaccination might be beneficial.

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Optimization of Heavy Metal Tracing by Total Reflection X-ray Fluorescence: The Experts’ Tips

de Faria Barbosa,

Belo,

da Silva Carneiro

et al. 2024

Methods and Protocols in Food Science

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Examining the evidence that ethylmercury crosses the blood-brain barrier

Cited by 22 publications

References 38 publications

Rethinking treatment of mercury poisoning: the roles of selenium, acetylcysteine, and thiol chelators in the treatment of mercury poisoning: a narrative review

Rethinking treatment of mercury poisoning: the roles of selenium, acetylcysteine, and thiol chelators in the treatment of mercury poisoning: a narrative review

Gender-Dependent Effects of Thimerosal on Human Progenitor Neurons: A Potential Link to Regressive Autism

Optimization of Heavy Metal Tracing by Total Reflection X-ray Fluorescence: The Experts’ Tips

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