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2,4-Dichlorophenoxyacetic acid in developing rats alters behaviour, myelination and regions brain gangliosides
S B Rosso1, G B García, M J Madariaga
1Laboratorio de Toxicología Experimental, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Santa Fe, Argentina.
Insights
Exposure to 2,4-D in neonatal rats impacts brain development and behavior. Even reduced exposure levels affected myelin and gangliosides, suggesting potential neurodevelopmental risks.
Area of Science:
- Neuroscience
- Developmental Toxicology
- Environmental Health
Background:
- Neonatal exposure to environmental toxins can disrupt neurodevelopment.
- 2,4-Dichlorophenoxyacetic acid (2,4-D) is a widely used herbicide with potential neurotoxic effects.
- Understanding the impact of 2,4-D on developing nervous systems is crucial for public health.
Purpose of the Study:
- To investigate the effects of different neonatal exposure levels of 2,4-D on rat pup development.
- To assess the impact of 2,4-D on myelin deposition and ganglioside composition in the brain.
- To evaluate behavioral changes in rat pups following 2,4-D exposure.
Main Methods:
- Neonatal rats were exposed to 2,4-D at two different dose regimens (100 mg/kg from PND 7-25 or 70 mg/kg from PND 12-25).
- Behavioral tests including righting reflex, negative geotaxis, forelimb support, and open field were conducted.
- Brain ganglioside composition and myelin deposition were analyzed at postnatal day 25.
Main Results:
- Higher dose/longer exposure resulted in decreased body/brain weight, reduced GM1 ganglioside levels, diminished myelin, and widespread behavioral alterations.
- Lower dose/shorter exposure led to behavioral changes (forelimb support, open field) without affecting body/brain weight.
- Both exposure levels reduced GM1 (a key myelin ganglioside) and myelin deposition.
Conclusions:
- Neonatal 2,4-D exposure can impair neurodevelopment, affecting myelin and behavior even at lower doses.
- The observed effects on myelin and behavior suggest direct neurotoxic mechanisms, independent of undernutrition.
- These findings highlight potential risks of 2,4-D exposure during critical developmental periods.
Abstract:
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.