Role of retinal glial cells in neurotransmitter uptake and metabolism.
In addition to photoreceptors and neurons, glial cells (in particular Müller cells) contribute to the removal and metabolization of neurotransmitters in the neural retina. This review summarizes the present knowledge regarding the role of retinal glial cells in the uptake of glutamate, N-acetylaspartylglutamate, gamma-aminobutyric acid, glycine, and d-serine, as well as the degradation and removal of purinergic receptor agonists. Some major pathways of glutamate metabolism in Müller cells are described; these pathways are involved in the glutamate-glutamine cycle of the retina, in the defense against oxidative and nitrosative stress via the production of glutathione, and in the production of substrates for the neuronal energy metabolism. In addition, the developmental regulation of the major glial glutamate transporter, GLAST, and of the glia-specific enzyme glutamine synthetase is described, as well as the importance of a malfunction and even reversal of glial glutamate transporters, and a downregulation of the glutamine synthetase, as pathogenic factors in different retinopathies.
Bringmann
Andreas
A
Department of Ophthalmology and Eye Hospital, University of Leipzig, Germany. bria@medizin.uni-leipzig.de
Pannicke
Thomas
T
Biedermann
Bernd
B
Francke
Mike
M
Iandiev
Ianors
I
Grosche
Jens
J
Wiedemann
Peter
P
Albrecht
Jan
J
Reichenbach
Andreas
A
D000818:Animals; D004734:Energy Metabolism / Q000502:physiology; D027341:Excitatory Amino Acid Transporter 1 / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism*; D006801:Humans; D009457:Neuroglia / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism; D018377:Neurotransmitter Agents / Q000378:metabolism*; D011983:Receptors, Purinergic / Q000378:metabolism*; D012160:Retina / Q000166:cytology / Q000378:metabolism*; D009435:Synaptic Transmission / Q000502:physiology
D027341:Excitatory Amino Acid Transporter 1; D018377:Neurotransmitter Agents; D011983:Receptors, Purinergic; D018698:Glutamic Acid