Abstract

FR.14.02

Retinal Müller glial cells: Physiological basics related to pathology

Reichenbach A.¹, Wurm A.², Pannicke T.¹, Yandiev Y.², Wiedemann P.², Bringmann A.^2
1Paul-Flechsig-Institut für Hirnforschung, Universität Leipzig, Leipzig; ²Klinik und Poliklinik für Augenheilkunde, Universität Leipzig, Leipzig

Objective: Background and purpose. Müller cells are the principal glial cells of the retina. Similar as the astrocytes in the brain, they constitute an anatomical and functional link between retinal neurons and blood vessels, and support the neurons by providing neurotrophic factors and blood-derived nutrients and by removing metabolic waste. Müller cells are responsible for the maintenance of the homeostasis of the retinal extracellular milieu (ions, water, neuro­transmitter molecules, and pH). They are involved in the control of angiogenesis, and in retinal blood flow regulation. Failure of their functions must thus cause severe impairment of the retina.
Methods: Various models of experimental retinal degeneration in the rat and pig are investigated, by applying electrophysiology, imaging methods, and immunostaining.
Results: In all cases studied, retinal degeneration caused Müller cell gliosis which was associated with a down-regulation and redistribution of K⁺ channels and a decrease of the K⁺ conductance. Gliotic Müller cells - but not normal control Müller cells - displayed swelling under hypoosmotic conditions, and underwent proliferative activity whereas their regular neuro-supportive functions failed.
Conclusions: The decrease in K⁺ conductance may be a key event in Müller cell gliosis, triggering a severe (further) impairment of neuronal function and survival.

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