抄録
We previously reported that survival of rat retinal ganglion cells (RGCs) after transection of the optic nerve (ON) was significantly enhanced by electrical stimulation (ES) to the ON stump (square pulses: 50 μA×50 μsec, frequency: 20 Hz, stimulation time: 2 hours). We here examined whether 20 Hz was optimal frequency for the ES, and whether ES delivered before the ON cut also enhanced survival of axotomized RGCs. After RGCs of adult rats were pre-labeled with FluorogoldTM applied to the bilateral superior colliculli, the left ON was transected intraocularly and ES was delivered before or after the ON cut. Seven days after the transection, the average rates of RGCs survival were determined by dividing the mean densities of labeled RGCs in the left retina by that in the right intact retina. With ES after the ON cut, we confirmed that ES at 20 Hz was effective for RGC survival: the survival rate of RGCs was 74 ± 7%, which was significantly higher (p<0.01) than sham operation (59 ± 5%). But ES at either 10 or 50 Hz was not effective. Concerning ES before the ON cut, we found ES at 300 μA was also effective for RGCs survival: the survival rate was 74 ± 6%, which was higher than sham operation (59 ± 5%, p<0.01). Additionally, when ES were delivered 3-hour before the ON cut, the effect went off. These results indicate that 20 Hz is optimal frequency for ES of 50 μA, and that it is important for RGCs survival that the ES is delivered just before or immediately after the ON cut. [Jpn J Physiol 54 Suppl:S164 (2004)]
