Typical and atypical spike-wave discharges: effects of penthylenetetrazole in wag/rij rats

Item does not contain fulltextIn this preliminary study the effects of PTZ-induced spike-wave discharges were studied and compared with those that occur spontaneously in a genetic model for human absence epilepsy. PTZ (20mg/kg) was administered in chronically EEG equipped WAG/Rij rats while control rats received solvent, the EEG was recorded for three subsequent hours. All rats showed spike and wave discharges (SWD) during baseline. After PTZ de novo PTZ-induced SWD appeared while the classical SWD remain present. Clear differences between spontaneous occurring SWD and by PTZ were found, most striking were the differences in intraspike frequency 4-6/sec and 7-9/sec respectively for the PTZ and classical SWD. In the second post-drug hour the number of PTZ induced SWD was decreased compared to the first hour, while the classical SWD were increased. In the last hour SWD were again the same as during baseline while the number of PTZ-induced SWD was further decreased. The same changes were observed for the mean duration of both type of SWD. It can be concluded that PTZ administration in WAG/Rij rats induced atypical discharges while the typical SWD were not altered. The increase in typical SWD in the second hour after PTZ administration may suggest a coupling between the typical and atypical SWD. However the discrepancy in the time of onset of the increase in the discharges induced by PTZ and spontaneous occurring SWD does suggest that they can be controlled by different mechanisms