Different reaction patterns of dopamine content to prenatal exposure to chlorpyrifos in different periods.

Developmental exposure to chlorpyrifos (CPF) induces abnormalities in neurotransmission. In the present study, we evaluated the dopamine reaction patterns in brain regions after CPF exposure during different prenatal periods. Animals were exposed on gestational days (GD) 7.5-11.5 or 13-17 and assessed at GD17, and at postnatal days (PN) 14 and 60. CPF exposure during GD7.5-11.5 elicited a decrease in dopamine content at each measurement stages, with more changes in the hippocampus than in the cerebral cortex. In contrast, CPF exposure in GD13-17 elicited a decrease in dopamine content at PN14 and PN60, with more changes in the cerebral cortex than in the hippocampus. These results suggest that the two key brain regions involved in learning and memory, the cerebral cortex and hippocampus, react differently to CPF exposure in different prenatal periods. The abnormalities did not recover long after cessation of CPF exposure and deficiencies persisted into pre-puberty and adulthood.