2005 Progress Report: Metals Neurotoxicity Research Project

EPA Grant Number: R831725C004
Subproject: this is subproject number 004 , established and managed by the Center Director under grant R831725
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: Harvard Center for Children’s Environmental Health and Disease Prevention Research
Center Director: Hu, Howard
Title: Metals Neurotoxicity Research Project
Investigators: Maher, Tim , Weisskopf, Marc
Institution: Harvard University
EPA Project Officer: Callan, Richard
Project Period: June 1, 2004 through May 31, 2009 (Extended to May 31, 2011)
Project Period Covered by this Report: June 1, 2005 through May 31, 2006
RFA: Centers for Children's Environmental Health and Disease Prevention Research (2003) RFA Text |  Recipients Lists
Research Category: Human Health , Children's Health

Objective:

The objectives of this research project are to:  (1) examine the effect of pre- and neonatal exposure to metals on neurochemical changes and neurobehavioral outcomes in rats; and (2) explore the potential modifying effect of stress on metals neurotoxicity.

Progress Summary:

As noted in the 2004 Annual Report for Project 4 (R831725C004), progress on this project experienced major administrative delays related to the execution of a subcontract with the Massachusetts College of Pharmacy.  All of this was resolved in Year 2.

During Year 2, Project 4 continued to develop and validate the neurochemical assays (e.g., dopamine, glutamate, and 8-OH-2’-dG) required to determine the effects of manganese (Mn), lead (Pb), or their combination in rat pups exposed in utero and through to weaning.  The limits of detection for each of the analytes of interest have been improved on during the year and now are:  dopamine––4 fmol on column; glutamate––100 fmol on column; and 8-OH-2’-dG––10 fmol on column.  Levels of dopamine and glutamate will be determined in microdialysates, whereas levels of 8-OH-2’-dG will be determined in brain and other tissues from the metal-exposed offspring.

During Year 2, information from Project 3 (R831725C003) suggested that the highest levels of Mn in the brain of animals would most likely be observed following intranasal instillation, with significantly lower levels in animals exposed to Mn orally. In preliminary studies, female rats have now been exposed to either Mn (high- and medium-dose levels), Pb (high-dose levels), or control water beginning at the time of breeding and continuing through to the time of weaning (PD-21).  Although animals exposed to the highest dose levels of Pb have appeared to have noneventful gestational periods compared to control animals, those exposed to the highest levels of Mn (30 mg/mL MnCl2) during gestation failed to hydrate adequately in these preliminary studies.  As the exposure is via the drinking water provided to the animals, an attempt at a lower exposure dose (15 mg/mL) also has been tried with similar problems.  Presently, even lower exposure doses of Mn are being investigated with the addition of a sweetener in an attempt to enhance fluid intake to an adequate level so as not to affect the gestation or lactation periods adversely because of poor hydration.  If it is determined that adequate daily fluid intake with Mn added to the drinking water cannot be achieved, an alternate method of exposure (e.g., oral gavage, injection, or inhalation) is planned.  Tissues from the offspring at the time of birth and at the time of weaning have been collected and will be processed for metal levels.

Protocols for the behavioral evaluation of the metal-exposed offspring have been established with the addition of the Morris water maze (MWM).  The addition of the MWM is because of the concerns with water/food deprivation required for the proposed operant chamber fixed-ratio waiting for reward and repeated acquisition and performance chamber protocols.  Additionally, the testing of very small weight animals (PD-21-25) as proposed originally is problematic because of the force required to activate the lever in the chamber by the animal.  The MWM does not involve food/water deprivation, and very young animals can easily perform this task, thereby eliminating the above concerns.  At present, only a few animals have been tested in the behavioral protocols as we try to optimize the exposure route and levels.

Future Activities:

The investigators did not report any future activities.

Journal Articles:

No journal articles submitted with this report: View all 12 publications for this subproject

Supplemental Keywords:

children, Native American, tribal, mixtures, lead, PBPK, community, Superfund, intervention, environmental management,, RFA, Health, Scientific Discipline, INTERNATIONAL COOPERATION, ENVIRONMENTAL MANAGEMENT, Waste, Environmental Chemistry, Health Risk Assessment, Hazardous Waste, Biochemistry, Children's Health, Hazardous, Risk Assessment, community-based intervention, fate and transport , developmental toxicity, Human Health Risk Assessment, neurodevelopmental toxicity, children's environmental health, mining waste, metal wastes, metals, human health risk, metal contamination

Relevant Websites:

http://www.hsph.harvard.edu/niehs/children Exit

Progress and Final Reports:

Original Abstract
  • 2004 Progress Report
  • 2006
  • 2007 Progress Report
  • 2008 Progress Report
  • 2009
  • Final

  • Main Center Abstract and Reports:

    R831725    Harvard Center for Children’s Environmental Health and Disease Prevention Research

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R831725C001 Metals, Nutrition, and Stress in Child Development
    R831725C002 Exposure Assessment of Children and Metals in Mining Waste: Composition, Environmental Transport, and Exposure Patterns
    R831725C003 Manganese, Iron, Cadmium, and Lead Transport from the Environment to Critical Organs During Gestation and Early Development in a Rat Model
    R831725C004 Metals Neurotoxicity Research Project