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Developmental cholinotoxicants: nicotine and chlorpyrifos.
1Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA. t.slokin@duke.edu
Environmental Health Perspectives
|May 7, 1999
Summary
Environmental toxins like chlorpyrifos disrupt neurodevelopment through both cholinergic and non-cholinergic pathways, impacting cell replication and differentiation from embryonic stages into postnatal life.
Area of Science:
- Neuroscience
- Developmental Biology
- Toxicology
Background:
- Cholinergic receptor stimulation is crucial for normal neurodevelopment.
- Environmental agents can disrupt neurodevelopment by altering cholinergic activity.
- Nicotine and cholinesterase inhibitors cause neurodevelopmental damage via cholinergic pathways.
Purpose of the Study:
- To investigate the mechanisms of chlorpyrifos-induced neurodevelopmental damage.
- To determine if chlorpyrifos exerts effects through both cholinergic and non-cholinergic pathways.
- To characterize the developmental window of vulnerability to chlorpyrifos.
Main Methods:
- Administered chlorpyrifos to developing rats and embryo cultures.
- Utilized in vitro studies with PC12 cells (lacking cholinesterase metabolite production).
- Assessed effects on DNA synthesis, cell numbers, apoptosis, and neuritic outgrowth.
Main Results:
- Chlorpyrifos decreased DNA synthesis and cell numbers in specific brain regions of rats.
- In embryo cultures, chlorpyrifos induced apoptosis during neurulation.
- In PC12 cells, chlorpyrifos inhibited DNA synthesis and cell replication via non-cholinergic mechanisms, independent of cholinergic antagonists.
Conclusions:
- Chlorpyrifos causes neurodevelopmental damage through both non-cholinergic and cholinergic mechanisms.
- Effects span from early cell replication to later stages of differentiation and axonogenesis.
- Vulnerability to chlorpyrifos extends from embryonic to postnatal development.