Protein kinase C-ε contributes to a chronic inhibitory effect of IL-1β on voltage-gated sodium channels in mice with febrile seizure

Abstract

This study aimed to understand the role of Interleukin-1β in mouse febrile seizures. To investigate the chronic effects of raised Interleukin-1β on seizures, the sodium currents of hippocampal neurons were recorded by whole-cell voltage clamp. Interleukin-1β inhibited sodium currents in mouse hippocampal neurons and verified that protein kinase C epsilon contributed to the effect of Interleukin-1β exposure. The inhibitory effect was also identified in neurons from a protein kinase C epsilon null mutant mouse. Action potentials were recorded using a ramp depolarizing current. Peak spike depolarization was significantly reduced by Interleukin-1β treatment, and was abolished following the administration of a protein kinase C epsilon inhibitor, εV1-2. However, neither Interleukin-1β nor εV1-2 had any significant effect on spike threshold. Interleukin-1β reduced the amplitude of action potentials due to its inhibitory effect on sodium channels. This is hypothesised to decrease the release of presynaptic transmitters of neuroexcitability, thus exerting a neuroprotective role in excitotoxicity. To ascertain the role of protein kinase C epsilon on febrile seizures in vivo, a heated water-bath model was used to identify susceptible mice. It was found that protein kinase C epsilon reduced susceptibility to, and frequency of, febrile seizure onset. This may be related to the neuroprotective effect of Interleukin-1β on hippocampal neurons.