From PN23 until PN60, LEV (54 mg/kg, i.p.) was administered once daily to GAERS (n = 8), while control GAERS (n = 7) received saline (0.9 % NaCl, i.p.). All animals were implanted with four epidural EEG electrodes at PN51. EEG was recorded for 3 h daily, during the last 4 days of the treatment (PN57-PN60) and during 4 additional days after treatment had been terminated (PN61–PN64). The animals were monitored again at the age of 4 months (PN120–PN124), about 2 months after the last administration of LEV.
During treatment, epileptiform events in the LEV group were significantly reduced (62 % , P < 0.05) in comparison with the control group. During the following 4 days, epileptiform events were reduced in the LEV group, with an average difference of 53 % (P = 0.064). Once the animals had reached adult age, there was no difference in epileptiform events between the LEV group and controls.
In this study, chronic LEV administration induced a reduction in epileptiform events in young GAERS. This effect persisted to some extent after treatment cessation (PN61–PN64), which might indicate a slowing down of epileptogenic processes. However, at the age of 4 months all animals revealed a similar expression of epileptiform discharges.