Neurobiology of seizure predisposition in the genetically epilepsy-prone rat.

Seizure predisposition in the genetically epilepsy-prone rat (GEPR) is innately determined and these animals exhibit consistent and reproducible convulsive patterns. This epilepsy model is made up of 2 independently derived colonies of animals with each exhibiting a characteristic convulsive pattern. In response to a standardized acoustic stimulus, GEPR-3s exhibit moderate or clonic convulsions and GEPR-9s exhibit more severe tonic extensor convulsions. Besides exhibiting convulsions in response to sound stimulation, some GEPRs experience spontaneous and hyperthermic seizures. They are also abnormally sensitive to a number of seizure provoking stimuli that produce seizures in normal animals. The neurochemical basis for the seizure predisposition in GEPRs is increasingly well understood. Abnormalities in central nervous system norepinephrine and serotonin are widespread and may play a prominent role in regulation of seizures in the GEPR. Amino acid neurotransmitter systems are less well defined in the GEPR but abnormalities exist and may be, along with other documented deficiencies, responsible in part for the seizure predisposition that is characteristic of GEPRs.