Brilliant blue G treatment facilitates regeneration after optic nerve injury in the adult rat

Injuries to the adult mammalian visual system often lead to functional deficits with little or no chance of spontaneous recovery. Previous studies in rats have demonstrated beneficial effects of inhibition of the P2X7 receptor with brilliant blue G (BBG) after spinal cord injury; however, little is known about BBG as a potential treatment strategy for optic nerve injuries. Adult Sprague–Dawley rats were subjected to a controlled optic nerve crush lesion and randomized to treatment with BBG (50 mg/kg body weight intravenously) or vehicle for 2 days after injury. The temporal pattern of axonal breakdown and regeneration, as well as formation of the glial scar and microglia/macrophage activation, was studied at 7, 14, and 28 days after lesion induction by immunohistochemical analysis. Results show reduced glial scar formation, less macrophage activation, and signs indicative of axonal regeneration beyond the glial scar in treated animals. No significant side effects from the treatment were observed. Effects on axonal breakdown, regeneration, and glial scar formation are discussed in relation to the proposed beneficial effects of BBG treatment. The present study demonstrates positive effects of BBG treatment on neural repair after traumatic optic nerve injury, and also shows its feasibility as a proposed future clinical treatment strategy.