Minocycline as a neuroprotective agent in a rodent model of NAION

Abstract

Purpose: To study the neuroprotective properties of minocycline in a rodent model of NAION (rAION).

Methods: Two groups of 6-week-old Long Evans male rats (n=8/group) had rAION induction in the right eye following intravenous rose bengal injection and laser-induced photothrombosis of the optic nerve head. The controlateral eye was used as an untreated control. Treated animals were intraperitoneally injected with minocycline 22mg/kg/day, beginning 3 days before induction and continued until euthanasia 30 days after induction. Control animals were treated with intraperitoneal injection of PBS for the same time period. Scanning laser ophthalmoscopy (SLO), fluorescein angiography (FA), and optical coherence tomography (OCT) were performed at 1, 8, 15 and 30 days to assess peripapillary retinal nerve fiber layer (PRNFL) thickness. After euthanasia, retinae were flat mounted and immunostained with Brn3a. Retinal ganglion cells (RGCs) were counted by stereology using a manual method.

Results: PRNFL thinning was observed in the PBS-treated group by SLO beginning day 8 post-induction of NAION. The PBS-injected group exhibited a 47.9% average RGC loss in induced right eyes compared with control left eyes (p<0.05). In contrast, RGC loss was not observed by SLO at 8 days in the minocyclin-treated group, and stereology in this group revealed a 9.58% loss of RGCs compared with a 47.9% loss in control animals (PBS-injected group). This difference in loss was statistically significant. (p<0.05).

Conclusions: Minocycline appears to be an effective neuroprotective agent in a rode

Keywords: 615 neuroprotection • 613 neuro-ophthalmology: optic nerve • 610 nerve fiber layer