Alterations in Rat Hippocampal Glutamatergic System Properties After Prolonged Febrile Seizures

Febrile seizures in early childhood can lead to developmental disorders in the CNS. However, the specific mechanisms behind the impact of febrile seizures on the developing brain are not well-understood. To address this gap in knowledge, we employed a hyperthermic model of febrile seizures in 10-day-old rats and tracked their development over two months. Our objective was to determine the degree to which the properties of the hippocampal glutamatergic system are modified. We analyzed whether pyramidal glutamatergic neurons in the hippocampus die after febrile seizures. Our findings indicate that there is a reduction in the number of neurons in various regions of the hippocampus in the first two days after seizures. The CA1 field showed the greatest susceptibility, and the reduction in the number of neurons in post-FS rats in this area appeared to be long-lasting. Electrophysiological studies indicate that febrile seizures cause a reduction in glutamatergic transmission, leading to decreased local field potential am-plitude. This impairment could be attributable to diminished glutamate release probability as evidenced by decreases in frequency of miniature excitatory postsynaptic currents and increases in pair-pulse ratio of synaptic responses. We also found higher threshold current causing hindlimb extension in the maximal electroshock seizure threshold test of rats 2 months after febrile seizures compared to control animals. Our research suggests that febrile seizures can impair glutamatergic transmission, which may protect against future seizures.