Translocation and Fluxes of Mercury in Neonatal and Maternal Rats Treated with Methyl Mercuric Chloride During Gestation 1

Summary

Pregnant rats, during the 16th day of gestation, were force-fed a tracer dose of ²⁰³Hg as methyl mercuric chloride. At parturition, 7, 14,21, and 28 days after parturition, the ²⁰³Hg radioactivities in the different brain parts and organs of maternal and neonatal rats were determined. The concentration of ²⁰³Hg in the brain, brain parts, and organs of mothers and pups decreased with time after force-feeding. At all time periods, cerebrum contained the greatest quantity of ²⁰³Hg and pituitary the lowest in both mothers and pups due primarily to the size of the tissue.

The blood concentration of ²⁰³Hg in the pups at birth was 27% higher than that of the darns. Similarly, at birth, the concentration of ²⁰³Hg in the different brain parts and organs of the pups, except in the kidney, was higher than corresponding tissues in the dams.

Mercury pool size in the brain and brain parts of maternal and neonatal rats also primarily reflected the size of the tissues studied. In general, a faster turnover of mercury in the pups was observed. The half-life of mercury in the maternal brain, kidneys, liver, and gastrocnemius were 10.79, 27.61,9.38, and 6.73 days, respectively. In the pups, corresponding half-life values were 10.00, 20.20, 13.50, and 12.86 days.

In another study, foster rearing of pups originally contaminated in utero with the radioactive mercury demonstrated that mercury excreted by pups recirculated to the foster dams. The uptake of ²⁰³Hg in the brain, brain parts and organs of foster dams ranged from 0.0001 to 0.067% of the original dose administered to the mothers of the contaminated pups.