PTZ-induced seizures in rats: effects of age and strain

Abstract

The susceptibility to pentylenetetrazol (PTZ)-induced seizures during postnatal ontogeny [postnatal day (PN) 10–220] was investigated in two rat strains. The WAG/Rij strain, genetically prone for developing generalized absence epilepsy, and Wistar rats were tested and compared at PN 10, 26, 30, 70, 90, 125, and 220 on the PTZ-convulsive threshold. A subconvulsive dose of 25-mg/kg PTZ was administered every 15 min, and the occurrence of clonic and tonic–clonic seizures was scored. The 10-day-old pups were quite sensitive to PTZ and showed mainly clonic seizures. The highest threshold and latency of PTZ-induced clonic and tonic–clonic convulsions were observed at PN 26 in both strains. From that age onwards, the seizure threshold significantly decreased and reached a minimum at PN 220. Between strain comparisons showed that WAG/Rij rats have a lower tonic–clonic seizure threshold than Wistar rats. The data indicate that changes in susceptibility first quickly decreases until PN 26–30 and then tend to monotonically increase with age, and that genetically prone nonconvulsive WAG/Rij rats are more vulnerable to convulsive seizures induced by PTZ than Wistar rats.