Untersuchung der elektrophysiologischen Eigenschaften retinaler Ganglienzellen in der degenerierten Rattennetzhaut

Hesse, Stephan; Walter, Peter (Thesis advisor); Wagner, Hermann (Thesis advisor); Müller, Frank (Thesis advisor)

Aachen : RWTH Aachen University (2021)
Dissertation / PhD Thesis

Dissertation, RWTH Aachen University, 2021

Abstract

The present paper examines the influence of photoreceptor degeneration on signal transduction in a degenerated retina. The results reveal severe changes in spontaneous spike activity and local field potentials in the retinal ganglion cells of a degenerated retina of a Royal College of Surgeons (RCS) rat. The experiments describe whether the remodeling in the outer retina and the change in the spontaneous activity of the inner network emanating from AII amacrine cells are the main actors causing the changes in the spontaneous spike activity and local field potentials seen in the retinal ganglion cells. With the use of pharmacological blockers it is analyzed whether glutamate, GABAA and gap junction-mediated signals are involved. Morphological changes are also observed. The results reveal that the degeneration of the retina of the RCS rat has a decisive influence on the development of both the vitreous body and the supplying blood vessels. It results in constrictions of axon bundles that lead to a massive decrease in neuronal spontaneous activity. This process is called neovasculation.A further subject that is discussed is the ability of the degenerated retina of an RCS rat to be stimulated in comparison to that of a healthy retina of a Wistar rat. In the experiments on this subject, three response patterns are evoked in the retinal ganglion cells by means of epiretinal stimulation in the RCS rat. We refer to them as direct, delayed and OFF response patterns. The direct and delayed responses are divided into single spike, single burst and bursty responses. Pharmacological blockers were used to identify the signaling pathway involved. It was found that neither delayed nor OFF responses are measured in the presence of bicuculline. Consequently, GABAergic signals, which are primarily mediated by amacrine cells, have a high impact on these response patterns. These patterns are not observed in the retina of a healthy Wistar rat. This indicates that induced retinal remodeling has a strong effect on signal processing in the inner plexiform layer and may also cause a change in the axonal resting potential.