The P2X7 receptor contributes to seizures and inflammation-driven
long-lasting brain hyperexcitability following neonatal hypoxia in mice
Abstract
Background and Purpose Neonatal seizures are a clinical emergency.
Current anti-seizure medications, however, fail to resolve seizures in
~50% of infants. The P2X7 receptor (P2X7R) is an
important driver of inflammation and evidence suggest P2X7R contributing
to seizures and epilepsy in adults. To date, however, no genetic proof
has been provided to determine the contribution of the P2X7R to neonatal
seizures, its effects on inflammatory signalling during neonatal
seizures and the therapeutic potential of P2X7R-based treatments on
long-lasting brain excitability. Experimental Approach Neonatal seizures
were induced via global hypoxia in 7 day-old mouse pups (P7). The role
of P2X7Rs during seizures was analyzed in P2X7R overexpressing and
knock-out mice. Treatment of wild-type mice post-hypoxia with the P2X7R
antagonist JNJ-47965567 was used to determine the effects of the P2X7R
on long-lasting brain hyperexcitability. Cell type-specific P2X7R
expression was analyzed via P2X7R-EGFP reporter mice. RNA sequencing was
used to monitor P2X7R-dependent hippocampal down-stream signalling. Key
Results P2X7R deletion reduced seizure severity whereas P2X7R
overexpression exacerbated seizure severity and reduced responsiveness
to anti-seizure medication. P2X7R deficiency let to an anti-inflammatory
phenotype in microglia and treatment of mice with a P2X7R antagonist
reduced long-lasting brain hyperexcitability. RNA sequencing identified
several pathways altered in P2X7R knock-out mice after neonatal hypoxia
including a down-regulation of genes implicated in inflammation and
glutamatergic signalling. Conclusion and Implications Treatments based
on targeting the P2X7R may represent a novel therapeutic strategy for
neonatal seizures with P2X7Rs contributing to the generation of neonatal
seizures, driving inflammatory processes and long-term hyperexcitability
states.