Abstract
Abstract: :
Purpose: Previously we demonstrated the neuroprotective effect of electrical stimulation to the transected optic nerve (ON) on axotomized retinal ganglion cells (RGCs) in adult rats (Morimoto et al, 2002). In this study, we introduced transcorneal electrical stimulation (TES) as a less invasive method and evaluated the neuroprotective effect of TES on axotomized RGCs. Methods: Adult male Wistar rats were used. Seven days after injection of Fluorogold (FG), a fluorescent tracer for retrograde labeling, into the superior colliculi, the left ON was transected ~3 mm from the posterior eye pole. TES was applied through concentric bipolar electrodes on a contact lens for 1 hour immediately after ON cut. The electrical stimuli were biphasic current pulses (1ms/phase, 100µA) of 20 Hz. One week after ON transection, mean RGC densities were calculated by the number of FG-labeled neurons counted in 12 areas covering the whole retina. Results: In normal retinas, the mean RGC density was 2368 ± 182 cells/mm2(mean ± SD). In ON transection group and sham stimulation group, the mean RGC densities significantly decreased to 53% and 51% of the density of normal retinas, respectively. On the other hand, TES increased the densities of surviving RGCs to 82% of normal value. The neuroprotctive effect of TES was comparable to that of TES to the transected ON. Conclusions: TES enhanced the survival of axotomized RGCs in adult rats. TES can be a new neuroprotective therapy for damaged RGCs.
Keywords: neuroprotection • ganglion cells • apoptosis/cell death