title: Astrocytes differentially respond to inflammatory autoimmune insults and imbalances of neural activity.
abstract: BACKGROUND
  Neuronal activity intimately communicates with blood flow through the blood-brain barrier (BBB) in the central nervous system (CNS). Astrocyte endfeet cover more than 90% of brain capillaries and interact with synapses and nodes of Ranvier. The roles of astrocytes in neurovascular coupling in the CNS remain poorly understood.
  
  
  RESULTS
  Here we show that astrocytes that are intrinsically different are activated by inflammatory autoimmune insults and alterations of neuronal activity. In the progression of experimental autoimmune encephalomyelitis (EAE), both fibrous and protoplasmic astrocytes were broadly and reversibly activated in the brain and spinal cord, indicated by marked upregulation of glial fibrillary acidic protein (GFAP) and other astrocytic proteins. In early and remitting EAE, upregulated GFAP and astrocytic endfoot water channel aquaporin 4 (AQP4) enclosed white matter lesions in spinal cord, whereas they markedly increased and formed bundles in exacerbated lesions in late EAE. In cerebellar cortex, upregulation of astrocytic proteins correlated with EAE severity. On the other hand, protoplasmic astrocytes were also markedly activated in the brains of ankyrin-G (AnkG) and Kv3.1 KO mice, where neuronal activities are altered. Massive astrocytes replaced degenerated Purkinje neurons in AnkG KO mice. In Kv3.1 KO mice, GFAP staining significantly increased in cerebellar cortex, where Kv3.1 is normally highly expressed, but displayed in a patchy pattern in parts of the hippocampus.
  
  
  CONCLUSIONS
  Thus, astrocytes can detect changes in both blood and neurons, which supports their central role in neurovascular coupling. These studies contribute to the development of new strategies of neuroprotection and repair for various diseases, through activity-dependent regulation of neurovascular coupling.
authors.affiliation: Biomedical Sciences Graduate Program, The Ohio State University, Columbus, OH 43210, USA. gu.49@osu.edu.
authors.forename: Peter
authors.initials: P
authors.lastname: Jukkola
authors.forename: Tomas
authors.initials: T
authors.lastname: Guerrero
authors.forename: Victoria
authors.initials: V
authors.lastname: Gray
authors.forename: Chen
authors.initials: C
authors.lastname: Gu
mesh_terms: D000818:Animals; D017487:Ankyrins / Q000235:genetics / Q000378:metabolism; D051401:Aquaporin 4 / Q000378:metabolism; D001253:Astrocytes / Q000276:immunology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001921:Brain / Q000276:immunology*; D002908:Chronic Disease; D004681:Encephalomyelitis, Autoimmune, Experimental / Q000276:immunology*; D005260:Female; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D009186:Myelin Sheath / Q000276:immunology; D009474:Neurons / Q000502:physiology; D012720:Severity of Illness Index; D051670:Shaw Potassium Channels / Q000235:genetics / Q000378:metabolism; D013116:Spinal Cord / Q000276:immunology*; D014746:Vimentin / Q000378:metabolism
chemical_list: C094681:Ank3 protein, mouse; D017487:Ankyrins; C496031:Aqp4 protein, mouse; D051401:Aquaporin 4; D001426:Bacterial Proteins; D005904:Glial Fibrillary Acidic Protein; C490839:Kcnc1 protein, mouse; D008164:Luminescent Proteins; D051670:Shaw Potassium Channels; D014746:Vimentin; C054562:yellow fluorescent protein, Bacteria