Novel Role of Gap Junctions Identified in Trigeminal Neuropathic Pain

Novel Role of Gap Junctions Identified in Trigeminal Neuropathic Pain

Trigeminal neuropathic pain is a chronic condition characterized by intense, recurrent episodes of facial pain. Recent research has demonstrated a potential role for glial gap junctions in neuropathic pain. A new study published by UTCSP researchers aimed to determine whether gap junctions contribute to trigeminal neuropathic pain in an animal model. Partial transection of the infraorbital nerve in rats resulted in mechanical hypersensitivity and central sensitization of nociceptive neurons characterized by increases in receptive field size, reduction of mechanical activation threshold and increases in noxious stimulation-evoked responses. The gap junction blocker carbenoxolone was applied intrathecally in male rats for a period of a week after nerve injury. Carbenxolone significantly decreased orofacial mechanical hypersensitivity and central sensitization after infraorbital nerve transection

This study provides the first evidence indicating a role of gap junctions in trigeminal neuropathic pain. Whether these gap junctions are specific to glia requires further investigation. Given that carbenxolone is already used for the clinical treatment of ulcers, it has the potential to be a safe and effective drug for the clinical treatment of trigeminal neuropathic pain. Therefore, investigation of the efficacy of carbenxolone in treating pain in humans is necessary.

Reference: H. Wang, Y. Cao, C-Y. Chiang, J.O. Dostrovsky, B.J. Sessle, The gap junction blocker carbenoxolone attenuates nociceptive behavior and medullary dorsal horn central sensitization induced by partial infraorbital nerve transection in rats, PAIN (2013) Article can be accessed at: http://dx.doi.org/10.1016/j.pain.2013.11.004