Background and aims
Trigeminal pain is a highly debilitating condition whose pharmacological treatment represents an unmet medical need. Anthocyanins are known to protect against a number of degenerative diseases, and they significantly accumulate in the brain. Additionally, the concept of “gut-brain axis” is emerging as a bidirectional signaling between the gut microbiota and the CNS. Therefore, we aimed at studying the role of an anthocyanin-rich dietary supplement in preventing trigeminal pain and in modulating the composition of the gut microbiota.

Methods
Male rats received a purple corn extract with increased anthocyanins content or yellow corn without anthocyanins or water as controls for 10 days. Trigeminal sensitization was then induced by unilateral injection of Complete Freund’s Adjuvant in the temporomandibular joint, followed by evaluation of mechanical allodynia. Microglia/macrophages activation was analyzed by immunohistochemistry. The bacterial taxonomic profile was reconstructed from fecal samples by 16S rRNA profiling protocol.

Results
Purple corn administration prevented the development of orofacial allodynia and the trigeminal infiltration of macrophages, with an effect comparable to the anti-allodynic action exerted by acetylsalicylic acid. No effect was seen in animals drinking either water or yellow corn. Purple corn also reduced microglial activation in vitro and in vivo, and modified the gut microbiota composition toward an anti-inflammatory taxonomic profile.

Conclusions
Purple corn extract prevents inflammatory pain through different cellular/molecular mechanisms that could also involve the gut-brain axis. Therefore, we foresee a possible application of anthocyanin-rich dietary supplements as co-adjuvant to pharmacological treatments or as new preventive strategy against trigeminal pain.

PURPLE CORN EXTRACT AS ADJUVANT THERAPY FOR THE PREVENTION AND TREATMENT OF TRIGEMINAL PAIN: ROLE OF MICROGLIA AND OF THE GUT MICROBIOTA