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Prenatal chlorpyrifos exposure in rats causes persistent behavioral alterations
Edward D Levin1, Nii Addy, Avanti Baruah
1Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC 27710, USA. edlevin@duke.edu
Neurotoxicology and Teratology
|December 4, 2002
Summary
Prenatal exposure to chlorpyrifos (CPF) in rats causes long-term cognitive deficits, particularly in females, affecting memory and learning. These effects were more pronounced at lower doses and suggest gender-specific neurodevelopmental impacts.
Area of Science:
- Neuroscience
- Toxicology
- Developmental Biology
Background:
- Chlorpyrifos (CPF) is an organophosphate insecticide known for developmental neurotoxicity.
- Previous studies focused on postnatal CPF exposure; effects of prenatal exposure are less understood.
- Prenatal exposure occurs during critical neurodevelopmental periods.
Purpose of the Study:
- To investigate the long-term cognitive effects of late prenatal chlorpyrifos (CPF) exposure in rats.
- To determine gender-specific differences in CPF-induced neurodevelopmental toxicity.
- To explore the role of cholinergic systems in mediating CPF's effects.
Main Methods:
- Pregnant rats were administered CPF (1 or 5 mg/kg/day) on gestational days 17-20.
- Offspring were tested in T-maze, Figure-8, and 16-arm radial maze tasks from adolescence to adulthood.
- Cognitive performance was assessed, followed by challenges with muscarinic (scopolamine) and nicotinic (mecamylamine) antagonists.
Main Results:
- Prenatal CPF exposure caused lasting cognitive impairments, primarily in female rats, affecting working and reference memory.
- Females exposed to CPF showed altered responses to scopolamine, suggesting compensatory mechanisms.
- Locomotor hyperactivity and slower habituation were observed in CPF-exposed females.
- Surprisingly, the lower CPF dose (1 mg/kg) induced more severe effects than the higher dose (5 mg/kg).
- Males did not exhibit significant cognitive deficits.
Conclusions:
- Late prenatal exposure to chlorpyrifos induces gender-selective, long-term cognitive deficits in rats.
- Compensatory mechanisms may underlie preserved performance in CPF-exposed females under basal conditions.
- The findings highlight the vulnerability of the developing brain to CPF and the complexity of its neurotoxic effects.