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Grantee Research Project Results

Grantee Research Project Results

Does Chlorpyrifos Target Glial Cell Development?

EPA Grant Number: U915722
Title: Does Chlorpyrifos Target Glial Cell Development?
Investigators: Garcia, Stephanie J.
Institution: Duke University
EPA Project Officer: Edwards, Jason
Project Period: May 1, 2000 through May 1, 2003
Project Amount: $78,000
RFA: STAR Graduate Fellowships (2000)
Research Category: Fellowship - Toxicology , Academic Fellowships , Health Effects

Description:

Objective:

The objective of this research project is to determine whether chlorpyrifos (CPF)-induced neurotoxicity is attributable to alterations in glial cell development.

Approach:

This project involves both in vitro and in vivo assessments in the developing brain. To examine adverse outcomes and mechanisms of CPF exposure on glial-type cells, researchers used the C6 glioma cell line. One advantage of this system is that effects on glial-type cells can be compared to neuronal-type cells (PC12). DNA and protein synthesis were measured by determining radiolabeled precursor uptake in proliferating cells. To elucidate critical periods of vulnerability and mechanisms involved, CPF effects on the adenylyl cyclase signaling casade and on DNA binding to transcription factors in proliferating and differentiating cells were compared. Further, because CPF sensitizes cells to oxidative damage, the generation of reactive oxygen species (ROS) were measured. The researchers will investigate effects on glial development in vivo by monitoring neuronal and glial specific markers after CPF exposure in fetal and neonatal rats. In particular, immunoblotting of glial fibrillary acidic protein (GFAP) will be used to determine whether CPF alters gliogenesis, myelin basic protein (MBP) to determine whether axonogenesis is interrupted, and neurofilament (NF) to contrast effects on neuronal development. Use of different brain regions (forebrain, midbrain-brainstem, and cerebellum) and exposure paradigms (gestation day 17?20, postnatal day 1-4, 11-14, and 21-24) will allow assessment of critical periods of vulnerability.

Expected Results:

This work is expected to result in a better understanding of how CPF disrupts development and also will identify the critical periods and the specific cellular targets. If glial cells are more sensitive to the developmental effects of CPF, this approach also may lead to more sensitive and rapid screening procedures for related developmental neurotoxins.

Supplemental Keywords:

chlorpyrifos, organophosphate pesticide, neurotoxicity, cholinergic, development, glia, neuron, C6 glioma, in vitro, differentiation, adenylyl cyclase, reactive oxygen species, transcription factors, rat, in vivo, gliogenesis, axonogenesis, GFAP, MBP, NF., Health, Scientific Discipline, PHYSICAL ASPECTS, ENVIRONMENTAL MANAGEMENT, Environmental Chemistry, Health Risk Assessment, Epidemiology, Risk Assessments, Biochemistry, Physical Processes, Risk Assessment, altered gene expression, developmental neurotoxicology, chemical exposure, toxicology, exposure, pesticides, chlorpyrifos, developmental effects, glial cell development, human exposure, exposure assessment, human health risk, cell culture

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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