EPILEPTIC NEURONS INDUCE AUGMENTING SYNAPTIC DEPOLARIZATIONS IN NONEPILEPTIC NEURONS (BUCCAL GANGLIA, HELIX-POMATIA)

Spread of epileptic activity was studied by inducing epileptiform acti vity (pentylenetetrazol, PTZ) in one part of a nervous system and by a nalyzing responses of neurons in a non-PTZ-treated part (identified ne urons, paired buccal ganglia, Helix pomatia). Paroxysmal depolarizatio n shifts (PDS) induced time-locked depolarizations in non-epileptic ne urons (latency ca. 5 s, duration ca. 1 min, amplitude less than or equ al to 20 mV). Amplitudes were augmenting during several hours of epile ptic activity. Depolarizations were accompanied by an increase in memb rane resistance and they were blocked in 'high Mg-low Ca' solutions. I t is assumed that the potentials represent a typical widespread respon se of non-epileptic neurons to PDS of other neurons. This response may be induced via non-specific releases of substances of the epileptical ly active neurons thereby activating neighboring neurons which in turn activate neurons in control ganglion. (C) 1997 Elsevier Science Irela nd Ltd.