gms | German Medical Science

Objective: In retinitis pigmentosa (RP) the photoreceptors degenerate over time but the retinal network, in particular the ganglion cells (RGCs) persist, providing a target for electrical stimulation by retinal prostheses. However, changes induced by retinal remodeling might interfere with this therapeutic approach. We, therefore, investigated changes in the inner retina of a mouse model of RP, the rd10 mouse.

Methods and Results: Using immunohistochemistry, we observed that the photoreceptors degenerate over time. Inner retinal cells did not degenerate but we observed both losses of dendrites as well as dendritic sprouting in the horizontal cells and bipolar cells. In electrophysiological recordings using multielectrode arrays (MEA), we observed rhythmic electrical activity. Regular patterns of local field potentials (LFP) occurred with frequencies between 3-5 Hz. Rhythmic bursts in RGC spiking were often observed phase-locked to LFPs. This kind of activity was not observed in wild type retinae. Preliminary pharmacological analysis suggests that both excitatory as well as inhibitory mechanisms are involved in the generation of spontaneous rhythmic activity in rd10 retinae.

Conclusion: In rd10 retinae, a pronounced rhythmic electrical activity is observed. It will be important to investigate, whether this activity compromises the efficacy of electrical stimulation by retinal prostheses.

Acknowledgment: This work was supported by the DFG grant MU 3036/2-1.