Tohoku J. Exp. Med., 2002, 196 (2)

Review

Placental to Fetal Transfer of Mercury and Fetotoxicity

MINORU YOSHIDA

Department of Chemistry, St. Marianna University School of Medicine, Kawasaki 216-8511

Mercury vapor is known penetrate the placental barrier more easily than inorganic mercury. A relative amount of mercury accumulates in the fetus after exposure of pregnant animals to mercury vapor. Mercury concentration in fetal organs is much lower than that in maternal organs except the liver, and fetal liver shows significantly higher mercury concentrations than maternal liver. In fetal liver, a substantial portion of mercury is bound to metallothionein (MT), which plays an important role as a reservoir of mercury during the prenatal period. The mercury retained in fetal liver is redistributed to other organs, such as the brain and kidney, with diminishing MT levels during postnatal development. Consequently, an increase in mercury concentration in the brain and kidney of the neonate is observed. In studies on animal offspring in utero exposed to mercury vapor, behavioral changes, such as radial arm maze, morris maze and lever-press durations, are observed when the levels of mercury vapor exceed the threshold limit value (TLV).

Keywords —— Mercury vapor; placental transfer of mercury; fetotoxicity; metallothionein

© 2002 Tohoku University Medical Press

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Tohoku J. Exp. Med., 2002, 196, 79-88

Address for reprints: Minoru Yoshida, Ph.D., St. Marianna University School of Medicine, 2-16-1 Sugao, Miyamae-ku, Kawasaki 216-8511, Japan.

e-mail: m2yosida@marianna-u.ac.jp

This paper was presented at the Sendai Symposium: Paradigm Shift in Heavy Metal Toxicology held on November 21-22, 2001.