Astrocytic Kir4.1 ion channel deficit drives persistent inflammatory facial pain in males

Chronic facial pain, a frequent and disabling condition, is maintained by central sensitization, which results in pain hypersensitivity. Although it is well established that reactive astrocytes play a key role in persistent pain mechanisms, the role of disruption of the normal capacity of astrocytes to maintain neuronal homeostasis is much less known. Here we show that persistent facial inflammation disturbs potassium homeostasis in the medullary dorsal horn of male rats, due to a sex-specific, drastic downregulation of astroglial inward rectifier potassium Kir4.1 channels. Using selective genetic tools, we establish that such downregulation, likely due to the release of IL-1β during inflammatory processing, is sufficient and required to drive pain hypersensitivity through altered K+ baseline levels. We further show that this chain of events can be prevented by selective upregulation of astroglial Kir4.1, or through systemic administration of 5-azacytidine, a DNA methylation modulator. Our results thus reveal a critical mechanism by which astrocyte dysfunction drives persistent inflammatory facial pain in males and discover the therapeutic potential of targeting central Kir4.1 for treating this disease.