Structural and visual functional deficits in a rat model of neuromyelitis optica spectrum disorders related optic neuritis

Neuromyelitis optica spectrum disorders (NMOSD) are a group of autoimmune astrocytopathies in the central nervous system, which are mainly caused by immunoglobulin G (IgG) against astrocyte water channel aquaporin-4 (AQP4). In this study, we aimed to establish a model of NMOSD-related optic neuritis (NMOSD-ON) and to evaluate the progressive changes of the optic nerve and visual function. AQP4 IgG-positive serum from NMOSD patients was injected into the subarachnoid space of the rat optic nerve to induce the NMOSD-ON model (AQP4 + group), and healthy serum was injected as the control. The visual evoked potential, pupillary light reflex and optical coherence tomography were monitored every week for 3 weeks after induction. Compared with the control group, the amplitude of the N1-P1 peak and pupillary light reflex in the AQP4+ group were reduced within the first week and then remained low thereafter. Consistent with the functional deficits, the thickness of the peripapillary retinal nerve fiber layer in the AQP4 + group was also greatly reduced. At the end of 3 weeks, there was a loss of retinal ganglion cells and the optic nerves showed characteristic NMOSD-like pathologic changes, including deposition of AQP4 IgG, local astrocyte damage, demyelination, microglia activation, macrophage infiltration and axonal injury. Thus, we have established an NMOSD-ON rat model with deficits in the optic nerve and visual function that may be a valuable tool for exploring the mechanism of NMOSD-ON and evaluating its potential therapeutic treatment.