CYCLIC-AMP ANALOGS INCREASE EXCITABILITY AND ENHANCE EPILEPTIFORM ACTIVITY IN RAT NEOCORTEX INVITRO

Effects of the cyclic AMP agonists 8-(4-chlorophenylthio)-adenosine 3' : 5' cyclic monophosphate (CPT-cAMP), dibutyryl cyclic AMP (dbcAMP) an d forskolin were studied on extracellular field potentials in rat neoc ortex slices in vitro. CPT-cAMP and forskolin produced a prolonged enh ancement of epileptiform activity resulting from removal of Mg2+ from the bathing medium. DbcAMP had no apparent effect except at high conce ntrations (1 mM), when it reduced bursting activity. Field potentials observed following electrical stimulation of the corpus callosum in th e presence of Mg2+ were enhanced by CPT-cAMP and dbcAMP; however forsk olin was without effect. Intracellular recording techniques demonstrat ed a transient excitatory influence of dbcAMP. The results indicate a role for cyclic AMP in seizure mechanisms.