Capture of extracellular zinc ions by astrocytes

• Published in: Glia Vol. 54; no. 4; pp. 304 - 315
• Main Authors: Varea, Emilio, Alonso-Llosà, Gregori, Molowny, Asunción, Lopez-Garcia, Carlos, Ponsoda, Xavier
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.09.2006; Wiley-Liss
• Subjects: Animals; Astrocytes - drug effects; Astrocytes - metabolism; Astrocytes - ultrastructure; Biological and medical sciences; Cells, Cultured; Dose-Response Relationship, Drug; endocytosis; Endosomes - physiology; Endosomes - ultrastructure; Extracellular Space - drug effects; Extracellular Space - metabolism; fluorescence; Fundamental and applied biological sciences. Psychology; glia; Glial Fibrillary Acidic Protein - metabolism; Homeostasis; Immunohistochemistry; Isolated neuron and nerve. Neuroglia; Microscopy, Electron; Organelles - physiology; Organelles - ultrastructure; Rabbits; Sucrose - pharmacology; TSQ; Vertebrates: nervous system and sense organs; zinc; Zinc - metabolism; Glial cell; Endocytosis; TSQ; fluorescence; Neuroglia; Central nervous system; Astrocyte; Extracellular; glia; Zinc
• ISSN: 0894-1491; 1098-1136
• DOI: 10.1002/glia.20382

Synaptic zinc ions released during synaptic transmission interact with pre‐ and postsynaptic neuroreceptors, thus modulating neurotransmission. It is likely that they have to be efficiently cleared from the extracellular milieu to assure subsequent synaptic events. Both neurons and glia are assumed to participate in this clearance by mechanisms that are not fully understood. In this study, electron microscopic zinc cytochemistry has shown zinc‐electrondense particles associated with hippocampal astrocytic membranes frequently found accumulated in stacked lamellae. In cultured astrocytes, the use of zinc fluorochromes and endocytic markers allowed the simultaneous imaging of the capture of extracellular zinc simultaneously to plasma membrane markers; this endocytic process was inhibited by high sucrose concentrations. Finally, electron microscopy of zinc‐loaded and fluorochrome photoconverted cells demonstrated some early events of extracellular zinc capture as well as its late accumulation in lysosome‐like organelles. © 2006 Wiley‐Liss, Inc.