Comparison of the effects of drugs on hyperexcitability induced in hippocampal slices by withdrawal from chronic ethanol consumption
The effects of drugs, previously demonstrated to have a range of effects on the behavioural signs of ethanol withdrawal hyperexcitability, were examined in area CA1 in isolated hippocampal slices prepared after withdrawal from chronic ethanol in vivo. The decreases seen after the ethanol treatment in the thresholds for production of single and multiple population spikes were prevented when the dihydropyridine calcium channel antagonist, isradipine, was included in the perfusion medium at 4 μM. Another dihydropyridine, felodipine, which had no activity against withdrawal signs in vivo, did not affect the changes in field potentials, at concentrations up to 10 μM. Diltiazem, which increased withdrawal hyperexcitability in vivo, had no effect on the withdrawal changes in field potentials at 30 μM; higher concentrations affected the control slices. The novel anticonvulsant, gabapentin, at 1 μM but not at 100 nM, significantly decreased the signs of withdrawal hyperexcitability in the hippocampal slices. When the CCKB antagonist, CI988, was added to the bathing medium, at 1 μM, there were small, but significant decreases in the withdrawal hyperexcitability. The results showed that the actions of these drugs on the changes in the field potentials in isolated hippocampal slices were very similar to their previously demonstrated effects on the convulsive signs of ethanol withdrawal in vivo, but differences were seen in the corresponding comparison with anxiolytic actions in vivo.