Mitochondrial localization of glucocortocoid receptor in glial (Müller) cells in the salamander retina

• Published in: Glia 2003-01, Vol.41 (1), p.38-49
• Main Authors: Psarra, Anna-Maria G., Bochaton-Piallat, Marie-Luce, Gabbiani, Giulio, Sekeris, Constantine E., Tsacopoulos, Marcos
• Format: Article
• Language: English
• Subjects: Ambystoma; Animals; Biological and medical sciences; Cells, Cultured; cellular imaging; confocal laser scanning microscopy; Dexamethasone - pharmacology; Eye and associated structures. Visual pathways and centers. Vision; Fundamental and applied biological sciences. Psychology; glucocorticoid receptor; Glucocorticoids - pharmacology; Glutamic Acid - metabolism; Glutamic Acid - pharmacology; glutamine synthetase; Immunohistochemistry; Liver - cytology; Liver - metabolism; mitochondria; Mitochondria - metabolism; Neuroglia - cytology; Neuroglia - drug effects; Neuroglia - metabolism; Photoreceptor Cells, Vertebrate - cytology; Photoreceptor Cells, Vertebrate - metabolism; Receptors, Glucocorticoid - biosynthesis; retina; Retina - cytology; Vertebrates: nervous system and sense organs
• ISSN: 0894-1491; 1098-1136
• DOI: 10.1002/glia.10130

Glucocorticoid hormones regulate the transcription of nuclear genes by way of their receptors. In addition, these hormones modulate mitochondrial gene transcription by mechanisms that remain poorly understood. Using immunofluorescence labeling in isolated Müller and photoreceptor cells and in intact salamander retina, we found that the glucocorticoid receptor (GR) is localized in both cell types. Confocal laser scanning microscopy and double staining with cytochrome oxidase (COX) showed that GR is localized in the mitochondria of Müller cells, but not in the mitochondria of photoreceptors. GR also colocalizes with glutamine synthetase (GS) in the cytoplasm of Müller cells. GR is also localized in the microvilli of the distal process of Müller cells and in the synaptic terminal of photoreceptors. Pre‐incubation of Müller cells with 1 μM dexamethasone (DEX) for 7 h led to greater than 50% inhibition of the glutamate‐induced increase in mitochondrial NADH. This late effect of glucocorticoids on glutamate metabolism could be ascribed, in part, to a direct action of steroid hormones on mitochondrial metabolism. GLIA 41:38–49, 2003. © 2003 Wiley‐Liss, Inc.