The Effect of P2X7 Antagonism on Subcortical Spread of Optogenetically-Triggered Cortical Spreading Depression and Neuroinflammation
Migraine is a neurological disorder characterized by episodes of severe headache. Cortical spreading depression (CSD), the electrophysiological equivalent of migraine aura, results in opening of pannexin-1 megachannels that release ATP and triggers parenchymal neuroinflammatory signaling cascade in the cortex. Migraine symptoms suggesting subcortical dysfunction bring subcortical spread of CSD under the light. Here, we investigated the role of purinergic P2X7 receptors on the subcortical spread of CSD and its consequent neuroinflammation using a potent and selective P2X7 antagonist, JNJ-47965567. P2X7 antagonism had no effect on the CSD threshold and characteristics but increased the latency to hypothalamic voltage deflection following CSD showing that ATP acts as a mediator in the subcortical spread. P2X7 antagonism also prevented hypothalamic neuronal activation following CSD, revealed by bilateral decrease in hypothalamic c-fos positive neuron count. P2X7 antagonism further stopped the CSD-induced neuroinflammation revealed by decreased nuclear translocation of NF-kappa B-p65 in astrocytes and decreased HMGB1 release. Following CSD we observed an increase in neuronal cytoplasmic P2X7R signal in cortex and subcortical structures (thalamus, hypothalamus, striatum, hippocampus) concordant with the neuroinflammation which is also prevented by P2X7R antagonism. In conclusion, our data suggest that P2X7R plays an imperative role in CSD-induced neuroinflammation, subcortical spread of CSD and CSD-induced hypothalamic neuronal activation hence can be a potential target in migraine treatment.