Abstract

FR.15.03

Role of Müller cells in function and integrity of the retina

Andreas Reichenbach

Paul-Flechsig-Institut für Hirnforschung, Universität Leipzig, Leipzig

Background and purpose
During the last decades it turned out that normal functioning and integrity of the retina are crucially dependent on Müller glial cells. These cells support neuronal functioning (for instance, by their contribution to neurotransmitter metabolism) and survival (by feeding the neurons and removing their waste products). More recently it was shown that Müller cells may even modulate neuronal signal processing by releasing neuroactive substances upon stimulation.
Method
A specific experimental setup was generated to monitor Ca2+ rises in Müller cells after light stimulation of the photoreceptor cells. Furthermore, novel transgenic mice were generated. 
Results
We show that Müller cells ‘sense’ light-evoked neuronal activity in the retina, and respond by two distinct types of Ca2+ rises. All Müller cells display slow sustained Ca2+ responses to photoreceptor illumination whereas only sub-populations of Müller cells show fast, transient Ca2+ waves descending from their endfeet to the somata if high light intensities are applied. We hypothesize that these Ca2+ rises may trigger the relase of neuroactive molecules from the Müller cells which, in turn, modify neuronal activity. To test this hypothesis, we generated transgenic mice in which Ca2+ rises in Müller cells can be selectively induced by applying an ‘alien’ ligand. Presently we are studying how such glial Ca2+ transients will modify neuronal activity in retinal wholemount preparations.
Conclusions
In the retina a complex, mutual exchange of signals occurs between neurons and glial cells. This type of glia-neuron interaction may significantly contribute to mechanisms of visual information processing such as adaptation to bright light intensities.

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