To study the neuroprotective properties of minocycline in a rodent model of NAION.Methods
6 weeks old Long Evans male rats had induction of NAION in the right eye after intravenous injection of rose bengale and laser-induced photothrombosis of the head of optic nerve. Treated animals were injected intraperitonealy with minocycline 22mg/kg/day, 3 days before induction and until sacrifice. Controls were treated by PBS during the same period of time. SLO, fluorescein angiography, and OCT were performed at day 1, 8, 15 and 30 to monitor fiber loss. At day 30, all animals were sacrified and flatmounted retina were stained with BRn3a. Retinal ganglion cells (RGC) were counted by manual method per field on stereology.Results
Sixteen rats had induction of NAION in the right eye, while the left eye was used as an internal control. In the PBS-treated group, fiber loss was observed on SLO from the day 8 post-induction. In this group, RGC loss in the NAION eye was 47.9% compared to control eyes (p<0.05). In the minocyclin-treated group, RGC loss could not be observed on SLO, and stereology demonstrated a 9.58% loss compared to control eyes (not statistically significant).Conclusion
Minocycline seems to be an effective neuro protective agent in a rodent model of NAION, when administered before and after induction of NAION. The mechanisms involved in this neuroprotective effect are still to be further evaluated. This molecule could thus be a promising candidate, both in the treatment of NAION but also in the prevention of involvement of the fellow eye.