Changes in brain serotonin and 5-hydroxyindolacetic acid levels induced by 2,4-dichlorophenoxyacetic butyl ester.

Brain concentrations of Serotonin (5-HT) and 5-hydroxyindolacetic acid (5-HIAA) were determined in male, mother and virgin female adult rats after exposure to 69 mg/kg body weight/day of 2,4-dichlorophenoxyacetic butyl ester (2,4-Dbe) during 15 or 45 consecutive days. Both 5-HT and 5-HIAA concentrations were increased in the brain. These effects reverted to levels even lower than controls, when the animals were fed an untreated diet after the 2,4-Dbe treatment. High 5-HT and 5-HIAA brain concentrations were also observed in adult rats born from treated mothers (during pregnancy and lactancy) and fed with or without treated diet after weaning. Two different effects on serotoninergic system were detected: a transient effect if 2,4-Dbe was given to adult rats in a short period of time and a permanent effect if the herbicide was supplied during pre- and post birth period (rat brain development). However, in utero exposed but lactationally cross-fostered rat pups were not affected, suggesting that prenatal exposure did not have any influence on the postnatal status of the neurotransmitter(s).