Mercury toxicity and neurodegenerative effects

Area of Science:

• Environmental Health
• Toxicology
• Neuroscience

Background:

• Mercury is a highly toxic heavy metal with no known physiological role in humans, existing in elemental, inorganic, and organic forms.
• Historically and currently, mercury has been utilized in various applications including dyeing, gold purification, medicine, and household products, leading to potential human exposure.
• Different mercury forms exhibit distinct toxicity profiles, with elemental mercury (Hg0) vapor and methylmercury (MeHg) primarily affecting the central nervous system (CNS), while inorganic mercury salts target the kidneys.

Purpose of the Study:

• To elucidate the toxicological mechanisms of mercury exposure.
• To investigate the relationship between mercury exposure and neurodegenerative conditions such as Amyotrophic Lateral Sclerosis (ALS) and Alzheimer's Disease (AD).
• To explore the role of antioxidants and protective mechanisms against mercury-induced toxicity.

Main Methods:

• Review of existing literature on mercury toxicity and its effects on human health.
• Analysis of the biochemical pathways involved in mercury's cellular damage, including mitochondrial dysfunction and oxidative stress.
• Examination of the correlation between mercury exposure levels and the incidence/progression of neurodegenerative diseases.

Main Results:

• Methylmercury (MeHg) is identified as the most bioavailable and toxic organic mercury compound, accumulating in the CNS and disrupting endocrine function.
• Mercury's primary toxicity mechanism involves mitochondrial damage through glutathione (GSH) depletion and binding to thiol groups, leading to free radical generation.
• Mercury exposure induces mitochondrial dysfunction, reduces ATP synthesis, and increases lipid, protein, and DNA peroxidation, particularly in the brain.

Conclusions:

• Depletion of GSH, mitochondrial damage, increased lipid peroxidation, and oxidative stress in the brain are key factors in mercury-induced neurotoxicity.
• These mechanisms are implicated in the pathogenesis of neurodegenerative conditions like ALS and AD.
• Factors such as metallothionein content, GSH levels, selenium, and omega-3 fatty acids may play a role in modulating mercury toxicity and protective responses.