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Evaluation of Synaptic Multiplicity Using Whole-cell Patch-clamp Electrophysiology
Published on: April 23, 2019
Adenosine A1 receptors presynaptically modulate excitatory synaptic input onto subiculum neurons
Nicholas J Hargus1, Edward H Bertram, Manoj K Patel
1Department of Anesthesiology, University of Virginia, Charlottesville, VA 22908, USA.
Brain Research
|May 20, 2009
Summary
Adenosine, acting on A(1) receptors, suppresses excitatory synaptic transmission in the subiculum, a key hippocampal output. This neuromodulator reduces neuronal excitability through a presynaptic mechanism.
Area of Science:
- Neuroscience
- Neuropharmacology
Background:
- Adenosine is an endogenous neuromodulator known to decrease neuronal excitability and synaptic transmission in the central nervous system (CNS).
- The subiculum, as the primary output region of the hippocampus, plays a critical role in information processing and memory consolidation.
Purpose of the Study:
- To investigate the specific actions of adenosine on excitatory synaptic transmission and neuronal excitability in the subiculum.
- To elucidate the receptor subtypes and cellular mechanisms underlying adenosine's effects in this brain region.
Main Methods:
- Electrophysiological recordings of excitatory postsynaptic currents (EPSCs) and miniature EPSCs (mEPSCs) in subiculum neurons.
- Application of adenosine, A(1) receptor agonist (CPA), A(1) receptor antagonist (DPCPX), and A(2A) receptor antagonist (ZM 241385).
- Assessment of action potential (AP) generation in response to synaptic stimulation and direct current injection.
Main Results:
- Adenosine (10 microM) significantly and reversibly inhibited EPSCs in subiculum neurons.
- These inhibitory effects were replicated by the A(1) receptor agonist CPA and blocked by the A(1) antagonist DPCPX, but not by the A(2A) antagonist ZM 241385.
- Adenosine and CPA reduced the frequency of mEPSCs without altering their amplitude, indicating a presynaptic action.
- Adenosine and CPA inhibited synaptically evoked action potentials but not those evoked by current injection, further supporting a presynaptic mechanism.
Conclusions:
- Adenosine modulates subiculum neuron excitability primarily through presynaptic A(1) receptors.
- These findings highlight the role of adenosine as a key regulator of hippocampal output pathways, influencing information flow from the hippocampus to other brain regions.
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