SUR1-Associated Mechanisms Are Not Involved in Ischemic Optic Neuropathy 1 Day Post-Injury

Ischemia-reperfusion injury after central nervous system (CNS) injury presents a major health care challenge with few promising treatments. Recently, it has become possible to reduce edema after CNS injury by antagonizing a sulfonylurea receptor 1 (SUR1) regulated ion channel expressed after injury. SUR1 upregulation after injury is a necessary precondition for the formation of this channel, and has been implicated in white matter injury after clinical spinal cord trauma. Glibenclamide, an SUR1 antagonist, appears to have neuroprotective effect against cerebral stroke in an open-label small clinical trial and great effectiveness in reducing damage after varied experimental CNS injury models. Despite its importance in CNS injuries, SUR1 upregulation appears to play no part in rodent anterior ischemic optic neuropathy (rAION) injury as tested by real-time PCR and immunohistochemical staining of rAION-injured rat optic nerve (ON). Furthermore, the SUR1 antagonist glibenclamide administered immediately after rAION injury provided no protection to proximal ON microvasculature 1 day post-injury but may reduce optic nerve head edema in a manner unrelated to ON SUR1 expression. Our results suggest that there may be fundamental differences between rAION optic nerve ischemia and other CNS white matter injuries where SUR1 appears to play a role.