Strain difference in mercury excretion in methylmercury-treated mice

Area of Science:

• Toxicology
• Environmental Health
• Pharmacokinetics

Background:

• Methylmercury (HgCl2) is a potent neurotoxin.
• Understanding strain-specific differences in mercury toxicokinetics is crucial for risk assessment.

Purpose of the Study:

• To investigate the influence of mouse strain on mercury excretion and organ distribution following methylmercury chloride administration.
• To identify potential mechanisms underlying observed strain differences.

Main Methods:

• Four male mouse strains (C57BL/6N, BALB/cA, C3H/HeN, AKR) were administered methylmercuric chloride (5 mg/kg).
• Mercury levels in urine, feces, blood, plasma, brain, liver, and kidney were measured over time.
• Plasma to whole blood mercury ratios were analyzed.

Main Results:

• C57BL mice exhibited 3.9-4.7 times higher urinary mercury excretion compared to other strains.
• AKR mice showed the highest fecal mercury levels.
• C57BL mice had lower blood mercury concentrations and significantly lower mercury levels in brain, liver, kidney, and blood after day 5.
• C57BL mice demonstrated higher initial mercury uptake in the brain and kidney.
• C3H mice had the highest brain and liver mercury levels, while BALB/c mice had the highest kidney mercury levels.

Conclusions:

• Mouse strain significantly influences methylmercury excretion and organ distribution.
• C57BL strain's rapid urinary excretion may be linked to higher plasma distribution and kidney uptake.
• Observed differences highlight the importance of genetic background in methylmercury toxicokinetics and toxicity.