Effects of methyl mercury in postnatal developing rats

Area of Science:

• Neuroscience
• Toxicology
• Developmental Biology

Background:

• Methylmercury chloride (MMC) is a known neurotoxin.
• Understanding developmental neurotoxicity is crucial for risk assessment.
• Postnatal development involves significant changes in organ systems and susceptibility to toxicants.

Purpose of the Study:

• To investigate the impact of methylmercury chloride (MMC) on rats at different postnatal developmental stages.
• To assess mercury (Hg) accumulation in the brain, liver, and kidney across various postnatal ages.
• To evaluate the effects of MMC on body weight, motor coordination, and neurological function.

Main Methods:

• Rats were orally administered varying doses of MMC (0-10 mg/kg/day) on postnatal days 1, 14, and 35 for 10 consecutive days.
• Mercury levels in brain, liver, and kidney were quantified.
• Body weight changes, hindlimb-crossing reflex, and rotarod performance were assessed.

Main Results:

• Brain Hg accumulation was highest in PD-14 rats, followed by PD-35 and PD-1 rats.
• Liver and kidney Hg accumulation increased with postnatal development.
• PD-35 rats showed the most severe body weight loss; motor deficits (hindlimb-crossing, rotarod impairment) varied significantly with age and dose.

Conclusions:

• Mercury distribution and MMC toxicity are highly dependent on the postnatal developmental stage in rats.
• Early postnatal exposure (PD-14) leads to higher brain mercury accumulation.
• Motor coordination deficits are more pronounced and persistent in rats exposed during later postnatal development (PD-14, PD-35).