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Neonatal chlordecone exposure impairs early learning and retention of active avoidance in the rat
Insights
Neonatal exposure to chlordecone (a pesticide) impaired active avoidance learning and memory in young rats, particularly males. This neurotoxic effect suggests developmental risks associated with chlordecone exposure.
Area of Science:
- Neurotoxicology
- Developmental toxicology
- Behavioral neuroscience
Background:
- Chlordecone is an organochlorine pesticide with known neurotoxic effects.
- Neonatal exposure to environmental toxins can have long-lasting impacts on brain development and behavior.
- Active avoidance tasks are standard behavioral models for assessing learning and memory in rodents.
Purpose of the Study:
- To investigate the effects of neonatal chlordecone exposure on active avoidance learning and memory in rats.
- To determine if chlordecone exposure impacts acquisition and retention of one-way and two-way active avoidance tasks.
- To assess potential sex-dependent differences in chlordecone's neurobehavioral effects.
Main Methods:
- Fischer-344 rat pups were administered chlordecone (1 mg/pup) or vehicle on postnatal day 4.
- Pups were trained and tested on one-way active avoidance (OWA) pre-weaning (day 18) and two-way active avoidance (TWA) post-weaning (days 28-30).
- Body weights, acquisition trials, retention latency, and extinction responses were recorded.
Main Results:
- Chlordecone exposure slightly reduced body weight in both sexes.
- Chlordecone impaired OWA acquisition, requiring more trials, especially in males.
- Chlordecone disrupted TWA performance, reducing sex differences and impairing retention, indicated by a loss of directional bias and increased responses during extinction.
Conclusions:
- Neonatal chlordecone exposure significantly impairs active avoidance learning and memory in rats.
- The neurotoxic effects of chlordecone are sex-dependent, with males showing more pronounced acquisition deficits.
- Chlordecone disrupts spatial learning and memory retention, suggesting a specific impact on cognitive functions related to environmental navigation.
Abstract:
The effect of neonatal exposure of rats to chlordecone on the acquisition and retention of active avoidance was investigated. Pups were trained and tested on one-way (preweaning) and/or two-way (post-weaning) active avoidance tasks. Offspring of Fischer-344 rats were administered 1 mg/pup of chlordecone (SC) dissolved in DMSO on postnatal day 4. Body weights were slightly, but significantly, depressed for chlordecone-exposed males (10-11%) and females (7-8%) during preweaning development. Post-weaning body weights were also slightly depressed by the chlordecone treatment (8% for the males, 7% for the females). For pups trained (day 18) on one-way (small to large compartment) active avoidance (OWA), chlordecone treatment increased the number of trials needed to attain the acquisition criterion; the effect was most pronounced in the males. A 72-hr retention test revealed a sex-dependent effect of chlordecone on response latency during the initial test trials. Acquisition of two-way avoidance (TWA) (days 28-30) was superior in female pups relative to males; chlordecone treatment significantly reduced this sex difference in pups which had prior or no prior OWA training. Perhaps most importantly, however, following prior OWA training, vehicle control pups demonstrated a directional bias to make an avoidance response from a small to a large compartment, whereas chlordecone-treated pups executed their avoidance responses in both directions at comparable rates. Similar evidence indicative of a selective retention deficit also characterized TWA performance when a "reversal" procedure was used. A final retention (extinction) session indicated that the chlordecone-treated pups made fewer responses than vehicle-treated controls during the test trials.(ABSTRACT TRUNCATED AT 250 WORDS)