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Decrease of recurrent and feed-forward inhibitions under high pressure of helium in rat hippocampal slices.
1G.S. Physiologie Hyperbare, CNRS, Faculté de Médecine Nord, Marseille, France.
European Journal of Pharmacology
|August 24, 1988
Summary
High helium pressure impairs GABAergic inhibition in rat hippocampus, leading to hyperexcitability. This suggests pressure affects ion channels, impacting synaptic transmission and neuronal function.
Area of Science:
- Neuroscience
- Physiology
- High-pressure physiology
Background:
- High pressure can alter neuronal function.
- Understanding pressure effects on synaptic transmission is crucial for diving and anesthesiology.
Purpose of the Study:
- To investigate the impact of high helium pressure on inhibitory synaptic transmission in the rat hippocampus.
- To determine if pressure affects GABAergic inhibition and neuronal excitability.
Main Methods:
- Extracellular recordings in rat hippocampal slices.
- Paired-pulse stimulation to assess feed-forward and recurrent inhibition.
- Application of GABA and muscimol to test receptor sensitivity.
Main Results:
- High helium pressure (80 atm) reduced the efficiency of GABAergic inhibition.
- Pressure did not significantly affect the response to exogenous GABA or muscimol.
- High pressure induced hyperexcitability in CA1 pyramidal cells, which was partially reversed by 2-aminophosphonovalerate or GABA.
Conclusions:
- High pressure decreases GABAergic inhibitory transmission efficiency but not GABAA receptor sensitivity.
- Pressure-induced hyperexcitability may result from reduced inhibition and facilitated NMDA-mediated excitation due to altered voltage-sensitive ion channels.