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Corticosterone-induced decrease of inhibitory postsynaptic potentials in rat hippocampal pyramidal neurons in vitro
A Teschemacher1, M L Zeise, W Zieglgänsberger
1Max-Planck-Institute of Psychiatry, Clinical Institute, Munich, Germany.
Neuroscience Letters
|September 6, 1996
Summary
Corticosterone (CORT) reduces hippocampal inhibition, but this effect disappears when intracellular factors wash out during whole-cell recordings. This suggests cytosolic factors are crucial for CORT
Area of Science:
- Neuroscience
- Cellular and Molecular Biology
- Neuroendocrinology
Background:
- Previous research indicated corticosterone (CORT) inhibits GABAergic synaptic transmission in rat hippocampal CA1 neurons.
- The precise mechanism and involvement of intracellular components remained unclear.
Purpose of the Study:
- To investigate the role of cytosolic factors in mediating CORT's effect on hippocampal CA1 neurons.
- To determine if intracellular milieu perturbation affects CORT-induced changes in synaptic inhibition.
Main Methods:
- Whole-cell gigaseal recordings were performed on rat hippocampal CA1 neurons in vitro.
- Comparison of electrophysiological data obtained with whole-cell recordings versus previous high-resistance sharp electrode studies.
Main Results:
- Perturbation of the intracellular milieu during whole-cell recordings abolished the CORT-induced decrease in inhibitory postsynaptic conductance.
- Corticosterone increased GABAA receptor-mediated conductances in approximately 50% of neurons under whole-cell recording conditions.
- CORT did not alter resting membrane potential, action potential amplitude, or input resistance in either recording condition.
Conclusions:
- The reduction in GABAergic synaptic inhibition by CORT in hippocampal CA1 neurons is dependent on cytosolic factors.
- These essential cytosolic factors are washed out during whole-cell gigaseal recordings, explaining the altered CORT effects.