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CNQX infused into entorhinal cortex blocks memory expression, and AMPA reverses the effect
J A Quillfeldt1, P K Schmitz, R Walz
1Departamento de Bioquimica, Instituto de Biociencias, UFRGS (centro), Porto Alegre, RS, Brasil.
Pharmacology, Biochemistry, and Behavior
|June 1, 1994
Summary
The entorhinal cortex is crucial for memory expression. Blocking AMPA receptors with CNQX impaired memory recall in rats, but AMPA administration counteracted this effect, highlighting the role of AMPA receptors.
Area of Science:
- Neuroscience
- Neurobiology
- Memory Research
Background:
- The entorhinal cortex plays a vital role in memory formation and retrieval.
- Understanding the specific receptor mechanisms involved in memory expression is crucial for neurobiological research.
Purpose of the Study:
- To investigate the role of AMPA receptors in the entorhinal cortex for memory expression.
- To determine the effects of CNQX and AMPA on memory recall in a step-down inhibitory avoidance task.
Main Methods:
- Rats were trained in an inhibitory avoidance task and tested for retention 26 days later.
- Bilateral cannulae were implanted targeting the entorhinal cortex.
- Infusions of CNQX (an AMPA receptor antagonist) and AMPA (an agonist) were administered prior to testing.
Main Results:
- Infusion of CNQX into the entorhinal cortex blocked memory expression, with effects lasting less than 90 minutes.
- AMPA alone had no effect, but it counteracted the memory-blocking effect of CNQX at a lower dose.
- CNQX administration prior to training did not affect acquisition, retention, or general activity, suggesting effects are specific to memory expression.
Conclusions:
- The integrity of AMPA receptors within the entorhinal cortex is essential for the expression of learned memories.
- These findings underscore the critical role of glutamatergic neurotransmission, specifically via AMPA receptors, in memory recall.