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MK-801 impedes the acquisition of a spatial memory task in rats
R L McLamb1, L R Williams, K P Nanry
1Laboratory of Molecular and Integrative Neuroscience, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709.
Abstract:
Several studies have reported that MK-801 impairs the acquisition of various learning and memory tasks, while others suggest that MK-801 may interfere with performance rather than having a specific effect on memory. To characterize further the effects of MK-801 on learning and memory, MK-801 (0.05 mg/kg, SC) was administered prior to or immediately after learning trials in a trial-independent water maze task. Since MK-801 may affect nonassociative variables that may influence learning and memory, motor activity and general reactivity measures were also determined for 0.0125, 0.025, or 0.05 mg/kg of MK-801 administered SC. Since MK-801 may also be used to treat children with epilepsy, we investigated the possible persistent cognitive effects on neonates. MK-801 (0.02 mg/kg, SC) was administered at postnatal days 9-15 and tested in the same task as above starting at day 36 of age. There were no persistent effects of neonatal treatment. However, in adult rats, MK-801 impaired the acquisition of the water maze task but did not affect performance during a recall task in the same apparatus. At doses affecting learning, there were no effects on motor activity or general reactivity in adult rats. These results are consistent with the conclusion that MK-801 interferes with acquisition of spatial learning in the rat.
Insights
MK-801 impairs spatial learning acquisition in adult rats but does not affect memory recall or motor activity. Neonatal exposure to MK-801 showed no persistent cognitive effects in later life.
Area of Science:
- Neuroscience
- Cognitive Psychology
- Pharmacology
Background:
- Conflicting reports exist on MK-801's impact on learning and memory.
- Some studies suggest MK-801 affects performance, not memory itself.
- MK-801 is explored for potential therapeutic uses, including in pediatric epilepsy.
Purpose of the Study:
- To clarify MK-801's specific effects on learning and memory acquisition versus performance.
- To investigate potential persistent cognitive effects of neonatal MK-801 exposure.
- To assess MK-801's impact on motor activity and reactivity.
Main Methods:
- Adult rats received MK-801 before or after water maze trials.
- Motor activity and reactivity were measured at various MK-801 doses.
- Neonatal rats (postnatal days 9-15) received MK-801 and were tested as adults.
Main Results:
- MK-801 impaired acquisition in the water maze task in adult rats.
- Performance during recall tasks was unaffected by MK-801.
- No persistent cognitive deficits were observed following neonatal MK-801 treatment.
- Motor activity and general reactivity remained unaffected at doses impacting learning.
Conclusions:
- MK-801 specifically interferes with the acquisition of spatial learning in adult rats.
- The drug does not appear to affect memory recall or motor functions at effective doses.
- Neonatal exposure to MK-801 does not lead to lasting cognitive impairments.