Experimental demyelinating optic neuropathy: a model for combined morphological and electrophysiological studies

A model is described for the morphological and electrophysiological study of demyelinative optic neuropathy in the rat. Cortical visual evoked potentials (VEPs) to flash stimuli were recorded before and after the intraneural microinjection of lysophosphatidyl choline (LPC) and galacto-cerebroside (Gal-C) antiserum. Progress was monitored by calculating the interocular latency differences (ILD) for the N40 and P60 components of the rat VEP, thus allowing a longitudinal evaluation of optic nerve function. Histological examination of the visual pathway using light and electron microscopy was performed at intervals through the course of the study. LPC produced a less selective lesion than did Gal-C antiserum. In lesions induced by the latter there was relatively little accompanying anoxal degeneration and subsequent remyelination was prominent. Control serum did not result in demyelination. This model should permit accurate electrophysiological and morphological correlations to be made during the developing and the reparative phases of demyelinative optic neuropathy and the assessment of potential therapeutic manoeuvres.