HIPPOCAMPAL SLICES FROM LONG-TERM STREPTOZOTOCIN-INJECTED RATS ARE PRONE TO EPILEPTIFORM RESPONSES

Evoked field potentials were recorded in the CA3, CA1 and dentate cyru s (DG) regions of hippocampal slices from rats injected with streptozo tocin (STZ; 60 mg/kg i.p.), to detect whether STZ-induced diabetes ent ails changes in hippocampal excitability. No change in hippocampal res ponsiveness was observed in slices from diabetic rats, up to 3 weeks p ost-STZ. Repetitive population spikes (PSs) reminiscent of an epilepti form hyperexcitability were, however, recorded in CA3 > CA1 > DG areas after more than 4 weeks ('long-term') post-STZ, although the maximal amplitudes were not different in STZ-diabetic versus control rats. Int racellular recordings on CA3 pyramidal neurons confirmed that fimbrial stimulation evokes significantly more action potentials in neurons fr om 'long-term' STZ diabetic versus control rats. This is the first rep ort of the appearance of repetitive hippocampal responses, particularl y in the seizure-prone CA3 area, as a long-term consequence of hypergl ycemic STZ treatment in rat. (C) 1998 Elsevier Science Ireland Ltd. Al l rights reserved.