Modulation of Long-term Potentiation in CA1 Region of Mouse Hippocampal Brain Slices by GABAA Receptor Benzodiazepine Site Ligands
Section snippets
MATERIALS AND METHODS
Extracellular recordings were made from the stratum radiatum in the CA1 region of mouse hippocampal brain slices. Slices (300–350 μm thick) were prepared from male C57 mice (20–40 weeks old) using methods as described previously for rat brain (Kemp et al., 1986). In brief, parasaggittal slices were submerged in a tissue chamber (volume 0.4 ml) by a continuously superfused (at 1–2 ml/min) artificial cerebrospinal fluid (ACSF) kept at 35°C and gassed with 95% O2/5% CO2. The ACSF contained (in
RESULTS
Excitatory postsynaptic potentials (e.p.s.p.s) in the stratum radiatum of the CA1 hippocampal region were elicited by orthodromic stimulation of the Schaffer collateral pathway with bipolar tungsten stimulating electrodes (5–50 V for a duration of 0.02 msec at 0.033 Hz). The effects of drugs on the induction of LTP by priming stimulus frequencies (priming stimulus; 10 events at 100 Hz) was compared with that induced by bursts of high-frequency stimuli (burst stimuli; 4 × 10 events at 100 Hz
DISCUSSION
This study provides further evidence that modulation of GABAA receptor function with benzodiazepines can regulate the plasticity of synaptic transmission from the Schaffer collateral commissural pathway to CA1 region of mouse hippocampus. The BZ agonist, flunitrazepam, suppressed the induction of long-term potentiation in a stimulus-dependent manner, whereas the inverse agonist DMCM facilitated its induction.
LTP was first described in vivo in the perforant path to dentate gyrus of rabbit
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