Emergence of delayed behavioral effects in offspring mice exposed to low levels of mercury vapor during the lactation period.
This study examined the emergence of delayed behavioral effects in offspring mice exposed to low levels of mercury vapor (Hg(0)) during the lactation period. Female offspring of mice were repeatedly exposed to Hg(0) at 0.057 mg/m(3), similar to the current threshold value (TLV), for 24 hr until the 20(th) day postpartum. The behavioral effects were evaluated with locomotor activity in the open field (OPF), learning activity in the passive avoidance response (PA) and spatial learning ability in the Morris water maze (MM) at the ages of 3 and 15 months. Hg(0)-exposed mice did not differ from controls in the three behavioral measurements at 3 months of age, and no neurobehavioral effects were observed. On the other hand, the mice exhibited significantly more central locomotion in the OPF task when tested at  15 months of age, but no abnormality in other behavioral performance. Immediately after postnatal exposure, the brain mercury concentration of offspring was about 150 times that of the control, in which the concentrations were approximately 0.4 µg/g. The results indicate that mice exposed to Hg(0) at concentrations around TLV during the developing period resulted in the emergence of delayed behavioral effects at a later stage in life.
Faculty of Human Health Sciences, Hachinohe University, Hachinohe, Japan. m2yosida@hachinohe-u.ac.jp
Minoru
M
Yoshida
Chiho
C
Watanabe
Akiko
A
Honda
Masahiko
M
Satoh
Akira
A
Yasutake
D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects; D001522:Behavior, Animal / Q000187:drug effects*; D001921:Brain / Q000378:metabolism; D004785:Environmental Pollutants / Q000493:pharmacokinetics / Q000633:toxicity*; D005260:Female; D007668:Kidney / Q000378:metabolism; D007774:Lactation; D008099:Liver / Q000378:metabolism; D018782:Maze Learning / Q000187:drug effects; D008628:Mercury / Q000493:pharmacokinetics / Q000633:toxicity*; D051379:Mice; D008810:Mice, Inbred C57BL; D009043:Motor Activity / Q000187:drug effects; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D014018:Tissue Distribution; D014835:Volatilization
D004785:Environmental Pollutants; D008628:Mercury