CHANGES IN SEROTONIN-IMMUNOREACTIVITY IN THE DORSAL AND MEDIAN RAPHE NUCLEI OF RATS EXPOSED TO 2,4-DICHLOROPHENOXYACETIC ACID THROUGH LACTATION

Comparison of serotonin-immunoreactive (SER-IR) neurons in nucleus rap he dorsalis (NRD) and median raphe nucleus (MRN) of 25-d-old rat pups exposed to 70 mg/kg/d 2,4-dichloro-phenoxyacetic acid through mothers milk and control pups was made using an immunohistochemical analysis. Significant 2,4-D-treatment-related increase in size and density of SE R-IR neuronal somata as well as in fiber length were observed. We post ulate that exposure to 2,4-dichlorophenoxyacetic acid on the first day of life would modify the synthesis of 5-HT or the maturation of the b rain serotonergic system.