Abstracts

Rationale: The absence seizures are one type of epilepsy which is characterized by a sudden loss of consciousness and with characteristic spike-wave discharges (SWD) in the electroencephalogram. Absence seizures are due to a dysregulation in the activity of the gamma-aminobutyric acid receptor type A (GABA_A) in the thalamo-cortical network which are modulate by the reticular nucleus of the thalamus (RNT) that ends the seizures. The aim of this study was to analyze the role of GABA_A receptors in the RNT on the SWD on adult male taiep rats.

Methods: We used 6-month-old taiep rats which were implanted with electrodes in the rostral RNT, cerebral cortex, neck muscles and in the right eye orbit for simultaneous recordings. Gaboxadol was infuse at 7.5, 15 y 30 µg/µL and bicuculline 50, 100 and 200 ng/mL in to rostral RNT through guide cannulas at 0800. We did four video-EEG recordings of 8 h, the first one is control, and three additional recordings using an increasing doses scheme every 72 h. Off-line we analyzed the frequency and mean duration of the SWD. We followed the NIH rules for the care and use of experimental animals and the protocol was approved by the University committee.

Results: Gaboxadol at the maximum dose abolished absence seizures during the first six hours of recording (P< 0.001), increasing its latency up to 650% (P< 0.001) with respect to control group (338 ± 144s). On the other hand, the administration of 100 ng/mL of bicuculline increased the number of absence seizures by two hours of recording (