Serotonin Strengthens a Developing Glutamatergic Synapse through a PI3K-Dependent Mechanism
Uwemedimo G Udoh1,2, John R Bruno1, Paige O Osborn1
1Department of Zoology and Physiology, University of Wyoming, Laramie 82071, Wyoming.
Summary
Serotonin modulates synaptic strength during development by regulating AMPA receptor currents independently of NMDA receptors. This finding reveals serotonin
Area of Science:
- Neuroscience
- Developmental Biology
- Synaptic Plasticity
Background:
- Synaptic strengthening during neural development typically involves NMDA receptor (NMDAR)-dependent AMPA receptor (AMPAR) upregulation.
- Serotonin is present in the developing vertebrate brain, suggesting a potential role in activity-dependent synapse formation and modulation.
Purpose of the Study:
- To investigate the role of serotonin in modulating synaptic transmission within the developing retinotectal projection of *Xenopus* tadpoles.
- To determine the receptor subtypes and signaling pathways involved in serotonin's effects on synaptic plasticity.
Main Methods:
- Whole-cell electrophysiological recordings from tectal neurons in *Xenopus* tadpoles (stage 48/49).
- Pharmacological manipulation of endogenous serotonin transmission and 5-HT2 receptor activity.
- Assessment of AMPA receptor-mediated currents at retinotectal synapses.
Main Results:
- Enhanced serotonin transmission upregulated AMPAR-mediated currents, while reduced transmission downregulated them.
- Inhibition of 5-HT2 receptors weakened AMPAR currents and blocked serotonin-induced synapse strengthening.
- Serotonin-dependent AMPAR current upregulation occurred via an NMDAR-independent, PI3K-dependent pathway.
Conclusions:
- Serotonin regulates AMPAR currents at developing synapses independently of NMDAR signaling.
- The 5-HT2 receptor and PI3K pathway are crucial for serotonin's effects on synaptic plasticity.
- Serotonin may act as a key modulator enabling activity-dependent plasticity during neural circuit development.
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