IMPAIRMENT OF FEEDFORWARD INHIBITION IN CA1 REGION OF HIPPOCAMPUS AFTER CHRONIC BENZODIAZEPINE TREATMENT

The strength of feedforward inhibition was assessed in the CA1 region of in vitro hippocampus of benzodiazeprine tolerant rats 2 and 7 days after 1 week oral flurazepam (FZP) administration. Feedforward inhibit ion was activated with a Schaffer collateral stimulation just-subthres hold for a population spike followed at intervals of 10-100 ms by test population spikes elicited from the subicular side of the recording e lectrode. The amplitude of test spike was reduced to a lesser degree 2 days, but not 7 days, after FZP treatment, suggesting a decrease feed forward inhibition in treated rats coinciding with the time course for reversal of anticonvulsant tolerance in vivo.