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GABA-activated Single-channel and Tonic Currents in Rat Brain Slices
Published on: July 17, 2011
Calcium-dependent changes of paired-pulse modulation at single GABAergic synapses
Mykola O Kravchenko1, Anastasia O Moskalyuk, Svetlana A Fedulova
1Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, 4, Bogomoletz str., 01024 Kiev, Ukraine.
Neuroscience Letters
|December 3, 2005
Summary
Extracellular calcium concentration critically influences synaptic plasticity in rat hippocampal neurons. Varying calcium levels not only alter synaptic strength but can also reverse the direction of paired-pulse plasticity.
Area of Science:
- Neuroscience
- Cellular Neuroscience
- Synaptic Plasticity
Background:
- GABAergic currents are crucial for regulating neuronal excitability in the hippocampus.
- Paired-pulse plasticity, a form of short-term synaptic plasticity, is sensitive to presynaptic calcium levels.
- Understanding calcium's role in synaptic plasticity is vital for comprehending neural circuit function.
Purpose of the Study:
- To investigate the impact of varying extracellular calcium concentrations on monosynaptic GABAergic currents in cultured rat hippocampal neurons.
- To determine how calcium modulates paired-pulse plasticity and its dependence on stimulus strength.
- To explore whether calcium concentration can alter the direction of paired-pulse plasticity.
Main Methods:
- Whole-cell patch-clamp recordings were employed to measure synaptic currents.
- Local electrical stimulation was used to evoke monosynaptic GABAergic postsynaptic currents (IPSCs).
- Extracellular calcium concentrations were manipulated (0.5 mM, 2 mM, 5 mM) to assess their effects.
Main Results:
- Paired-pulse depression was observed under normal calcium conditions (2 mM).
- Both IPSC amplitude and release probability showed a bell-shaped dependency on stimulus amplitude, which persisted across different calcium concentrations.
- Altering extracellular calcium levels (0.5 mM or 5 mM) modulated IPSC amplitude and release probability, and notably, inverted the direction of paired-pulse plasticity (facilitation in low calcium, depression in high calcium).
Conclusions:
- Extracellular calcium concentration is a key regulator of synaptic plasticity strength in hippocampal GABAergic synapses.
- Calcium levels can dictate the direction of paired-pulse plasticity, shifting from depression to facilitation or vice versa.
- These findings highlight the dynamic and calcium-dependent nature of short-term synaptic plasticity.
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