視神経損傷後の経角膜電気刺激による機能保護

抄録

Traumatic injury to the optic nerve often causes a rapid loss of vision within several hours and leads retinal ganglion cells to cell death with slower time course. The previous experiments demonstrated the neuroprotective effect of electrical optic nerve stimulation on the retinal cell death over several days or weeks. However, it is not clear whether the electrical stimulation effectively prevents the acute impairment of visual function as observed in the traumatic optic neuropathy. We examined whether the transcorneal electrical stimulation could improve visual function after the optic nerve crush. A screw electrode was secured on the skull over the visual cortex to record visually evoked potential (VEP) in adult rats. VEP elicited by flash stimuli was recorded before and after the optic nerve crush, and after the transcorneal stimulation to estimate the degree of damage and the effect of stimulation in individual animal. Calibrated optic nerve crush reduced the amplitude of VEP significantly in all animals (30% of pre-crush value on average). Transcorneal stimulation given through a bipolar electrode fitted to a contact lens (intensity 500μA, duration 50μsec, 20Hz, 6hours) significantly enhances VEP amplitude (270% of the post-crush value on average) and the enhancement was preserved for one week in most cases. These results suggest that the transcorneal stimulation has a protective effect against acute impairment of visual function by optic nerve crush. [J Physiol Sci. 2006;56 Suppl:S175]