Related Experiment Videos
Selective targeting of newly synthesized Arc mRNA to active synapses requires NMDA receptor activation
1Reeve-Irvine Research Center and, Department of Anatomy and Neurobiology, College of Medicine, University of California at Irvine, Irvine, CA 92697, USA. osteward@uci.edu
Abstract:
Newly synthesized Arc mRNA is selectively targeted to synapses that have experienced particular patterns of activity. Here, we demonstrate that the targeting requires NMDA receptor activation. Arc expression was induced by an electroconvulsive seizure, and the newly synthesized mRNA was then targeted to synaptic sites by activating the perforant path projections to the dentate gyrus. When micropipette electrodes containing NMDA receptor antagonists (MK801 or APV) were positioned in the dentate gyrus during the stimulation period, newly synthesized Arc mRNA was transported into dendrites but did not localize in the activated lamina; instead, the mRNA remained diffusely distributed. AMPA receptor antagonists (CNQX) blocked targeting of Arc mRNA in a small region, and mGluR antagonists (MCPG) did not affect localization. These results demonstrate that NMDA receptor activation is required for the targeting of Arc mRNA to active synapses.
Insights
Newly synthesized Arc messenger RNA (mRNA) targets active synapses, but this process requires N-methyl-D-aspartate (NMDA) receptor activation. Blocking NMDA receptors prevents Arc mRNA from localizing to active synapses.
Area of Science:
- Neuroscience
- Molecular Biology
- Synaptic Plasticity
Background:
- Newly synthesized Arc mRNA is known to selectively target synapses with specific activity patterns.
- Understanding the molecular mechanisms regulating Arc mRNA synaptic targeting is crucial for comprehending activity-dependent gene expression.
Purpose of the Study:
- To investigate the role of specific receptor activations in the synaptic targeting of newly synthesized Arc mRNA.
- To determine whether NMDA receptor activation is necessary for Arc mRNA localization to active synapses.
Main Methods:
- Induction of Arc expression via electroconvulsive seizure in a rodent model.
- Activation of perforant path projections to the dentate gyrus to induce synaptic activity.
- Pharmacological blockade of NMDA receptors (MK801, APV), AMPA receptors (CNQX), and mGluRs (MCPG) during stimulation.
- Analysis of Arc mRNA distribution within the dentate gyrus using in situ hybridization.
Main Results:
- NMDA receptor antagonists (MK801, APV) prevented the localization of newly synthesized Arc mRNA to the activated synaptic layer, with mRNA remaining diffusely distributed in dendrites.
- AMPA receptor antagonists (CNQX) partially blocked Arc mRNA targeting in a localized region.
- mGluR antagonists (MCPG) did not significantly affect Arc mRNA localization.
Conclusions:
- NMDA receptor activation is essential for the precise targeting of newly synthesized Arc mRNA to actively participating synapses.
- AMPA receptors may play a secondary or modulatory role in this targeting process.
- These findings elucidate a critical molecular step in activity-dependent synaptic plasticity and gene regulation.