Neuroprotectant FK506 inhibits glutamate-induced apoptosis of astrocytes in vitro and in vivo.
Neuron-astrocyte interactions are critical for signalling, energy metabolism, extracellular ion and glutamate homeostasis, volume regulation and neuroprotection in the CNS. Glutamate uptake by astrocytes may prevent excitotoxic glutamate elevation and determine neuronal survival. However, an excess of glutamate can cause the death of astrocytes. FK506, an inhibitor of calcineurin, and an immunosuppressive drug, is neuroprotective in animal models of neurologic diseases, including focal and global ischaemia. In the present work, we demonstrate that a single injection of FK506 60 min after a transient middle cerebral artery occlusion (MCAo) significantly decreases the number of terminal deoxynucleotidyl transferase nick-end labelling (TUNEL)-positive cells in the ischaemic cortex and striatum. Using 3-D confocal microscopy we found that, 24 h after MCAo, many TUNEL-positive cells in the ischaemic striatum and cortex are astrocytes. Furthermore, we demonstrate that exposure of cultured cortical astrocytes to 50-100 mM Glu for 24 h induces apoptotic alterations in nuclear morphology, DNA fragmentation, dissipation of mitochondrial transmembrane potential (DeltaPsi) and caspase activation. FK506 (1 muM) efficiently inhibits Glu-induced apoptosis of cultured astrocytes, DNA fragmentation and changes in mitochondrial DeltaPsi. Our findings suggest that modulation of glutamate-induced astrocyte death early after reperfusion may be a novel mechanism of FK506-mediated neuroprotection in ischaemia.
Szydlowska
Kinga
K
Laboratory of Transcription Regulation, Department of Cell Biology, The Nencki Institute of Experimental Biology, Warsaw, Poland.
Zawadzka
Malgorzata
M
Kaminska
Bozena
B
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001253:Astrocytes / Q000187:drug effects*; D015153:Blotting, Western; D020169:Caspases / Q000378:metabolism; D048429:Cell Size / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects; D053938:DNA Fragmentation / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D018691:Excitatory Amino Acid Antagonists; D005456:Fluorescent Dyes; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D018698:Glutamic Acid / Q000633:toxicity*; D020287:In Situ Nick-End Labeling; D007211:Indoles; D020244:Infarction, Middle Cerebral Artery / Q000473:pathology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology; D018696:Neuroprotective Agents / Q000494:pharmacology*; D051381:Rats; D015427:Reperfusion Injury / Q000473:pathology; D016559:Tacrolimus / Q000494:pharmacology*; D013778:Tetrazolium Salts; D013844:Thiazoles
D018691:Excitatory Amino Acid Antagonists; D005456:Fluorescent Dyes; D005904:Glial Fibrillary Acidic Protein; D007211:Indoles; D018696:Neuroprotective Agents; D013778:Tetrazolium Salts; D013844:Thiazoles; D018698:Glutamic Acid; C007293:DAPI; D020169:Caspases; C022616:thiazolyl blue; D016559:Tacrolimus