Neurobehavioral effects of combined prenatal exposure to low-level mercury vapor and methylmercury

• Yoshida Minoru

  Faculty of Human Health Sciences, Hachinohe University

• Suzuki Megumi

  Department of Chemistry, Meisei University

• Satoh Masahiko

  Laboratory of Pharmaceutical Health Sciences, School of Pharmacy, Aichi Gakuin University

• Yasutake Akira

  Biochemistry Section, National Institute for Minamata Disease

• Watanabe Chiho

  Department of Human Ecology, Graduate School of Medicine, University of Tokyo

Abstract

We evaluated the effects of prenatal exposure to low-level mercury (Hg⁰) or methylmercury (MeHg) as well as combined exposure (Hg⁰ + MeHg exposure) on the neurobehavioral function of mice. The Hg⁰ exposure group was exposed to Hg⁰ at a mean concentration of 0.030 mg/m³ for 6 hr/day during gestation period. The MeHg exposure was supplied with food containing 5 ppm of MeHg from gestational day 1 to postnatal day 10. The combined exposure group was exposed to both Hg⁰ vapor and MeHg according to above described procedure. After delivery, when their offspring reached the age of 8 weeks, behavioral analysis was performed. Open field (OPF) tests of the offspring showed an increase and decrease in voluntary activity in male and female mice, respectively, in the MeHg exposure group. In addition, the rate of central entries was significantly higher in this group than in the control group. The results of OPF tests in the Hg⁰ + MeHg exposure group were similar to those in the MeHg exposure group in both males and females. The results in the Hg⁰ exposure group did not significantly differ from those in the control group in males or females. Passive avoidance response (PA) tests revealed no significant differences in avoidance latency in the retention trial between the Hg⁰, MeHg, or Hg⁰ + MeHg exposure group and the control group in males or females. Morris water maze tests showed a delay in the latency to reach the platform in the MeHg and Hg⁰ + MeHg exposure groups compared with the control group in males but no significant differences between the Hg⁰, MeHg, or Hg⁰ + MeHg exposure group and the control group in females. The results of OPF tests revealed only slight effects of prenatal low-level Hg⁰ exposure (0.03 mg/m³), close to the no-observable-effect level (NOEL) stated by the WHO (0.025 mg/m³), on the subsequent neurobehavioral function. However, prenatal exposure to 5 ppm of MeHg affected exploratory activity in the OPF test, and, in particular, male mice were highly sensitive to MeHg. The MeHg and Hg⁰ + MeHg exposure groups showed similar neurobehavioral effects. Concerning the effects of prenatal mercury exposure under the conditions of this study, the effects of MeHg exposure may be more marked than those of Hg⁰ exposure.

Journal

• The Journal of Toxicological Sciences

  The Journal of Toxicological Sciences 36 (1), 73-80, 2011

  The Japanese Society of Toxicology

Keywords

• Mercury vapor
• Methylmercury
• Combined exposure
• Mice
• Neurobehavioral effects

Details

• CRID: 1390282679878374528
• NII Article ID: 10027420404
• NII Book ID: AN00002808
• DOI: 10.2131/jts.36.73
• ISSN: 18803989
• ISSN: 03881350
• NDL BIB ID: 10999473
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I10999473
• Web Site: http://www.jstage.jst.go.jp/article/jts/36/1/36_1_73/_pdf
• Web Site: https://search.jamas.or.jp/link/ui/2011323232
• Text Lang: en
• Data Source:
  • JaLC
  • NDL
  • Crossref
  • CiNii Articles
• Abstract License Flag: Disallowed