2,4-Dichlorophenoxyacetic acid in developing rats alters behaviour, myelination and regions brain gangliosides pattern.

Neonate rats were exposed to 100 mg/kg from the PND 7 to PND 25 or at 70 mg/kg from PND 12 to PND 25. Treated and control pups were subjected to several behavioral tests (righting reflex, negative geotaxy, forelimbs support and open field) during the period of treatment. At PND 25 the regional effects of 2,4-D on gangliosides composition and myelin deposition were determined. The results indicate that the first design of exposure to 2,4-D produces significant diminutions in body and brain weight from PND 21. Furthermore, these pups showed decrease in GM1 level, diminution in myelin deposition and alterations in all behavioral tests. On the other hand, when treatment was not too severe (minor dose and shorter period of treatment), pups showed alterations in forelimb support and in open field tests without body or brain weight modifications. They also presented diminutions in GM1, mayoritary ganglioside of myelin, and in myelin deposition. These results suggest that in this latter 2,4-D exposure design, undernutrition could not be involved.