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Piracetam facilitates long-term memory for a passive avoidance task in chicks through a mechanism that requires a
M Loscertales1, S P Rose, J N Daisley
1Brain and Behaviour Research Group, The Open University, Milton Keynes, UK.
Insights
Piracetam, a nootropic, enhances memory consolidation in chicks by modulating corticosteroid receptors. This cognitive enhancement effect is linked to the activation of mineralocorticoid and glucocorticoid receptors.
Area of Science:
- Neuroscience
- Pharmacology
- Animal Behavior
Background:
- Nootropics like piracetam are investigated for cognitive-enhancing properties.
- Long-term memory formation is influenced by brain corticosteroid actions.
Purpose of the Study:
- To investigate the effects of piracetam on learning and memory in a passive avoidance task in day-old chicks.
- To determine if piracetam's memory-enhancing effects are mediated by corticosteroid receptors.
Main Methods:
- A weak learning version of the passive avoidance task was used in day-old chicks.
- Piracetam was administered post-training, and memory recall was tested 24 hours later.
- The role of mineralocorticoid and glucocorticoid receptors was assessed using specific antagonists.
Main Results:
- Post-training piracetam injections significantly improved memory recall.
- Piracetam administration led to increased plasma corticosterone levels.
- Blocking mineralocorticoid and glucocorticoid receptors inhibited piracetam's memory-facilitating effects.
Conclusions:
- Piracetam modulates long-term memory formation in chicks.
- This modulation involves the activation of intracellular mineralocorticoid and glucocorticoid receptors.
- Piracetam's cognitive-enhancing effects are dependent on corticosteroid receptor signaling.
Abstract:
We investigated the effects of piracetam, a nootropic, on learning and memory formation for a passive avoidance task in day-old chicks. To test for the possible cognitive-enhancing properties of piracetam, a weak learning version of this task--whereby chicks maintain a memory to avoid pecking at a bead coated in a diluted aversant for up to 10 h--was used. Post-training (5, 30 or 60 min), but not pretraining, injections of piracetam (10 or 50 mg/kg, i.p.) increased recall for the task when the chicks were tested 24 h later. Because previous studies showed that long-term memory for the passive avoidance task is dependent upon a brain corticosteroid action, and because the efficacy of piracetam-like compounds is also modulated by corticosteroids, we tested whether the facilitating effect of piracetam was dependent upon a corticosteroid action through specific brain receptors (mineralocorticoid receptor and glucocorticoid receptor). First, increased plasma levels of corticosterone were found 5 min after piracetam injection. In addition, intracerebral administration of antagonists for each receptor type (RU28318, for mineralocorticoid receptors, and RU38486 for glucocorticoid receptors; i.c.) given before the nootropic inhibited the facilitative effect of piracetam on memory consolidation. These results give further support to a modulatory action of piracetam on the mechanisms involved in long-term memory formation through a neural action that, in this learning model, requires the activation of the two types of intracellular corticosteroid receptors.