title: Effect of penetrating brain injury on aquaporin-4 expression using a rat model.
abstract: Cerebral edema (CE) is a frequent and potentially lethal consequence of various neurotraumas, including penetrating brain injury (PBI). Aquaporin-4 (AQP4) water channel is predominantly expressed by astrocytes and plays an important role in regulating water balance in the normal and injured brain. Using a rat model of PBI, we show that AQP4 immunoreactivity was substantially increased in the peri-injury area at both 24 and 72 h after PBI. The increase in AQP4 expression was paralleled by increased GFAP expression. The two proteins were co-expressed by peri-vascular astrocytes, whereas reactive astroglia identified by their stellar morphology did not express AQP4 at either time points after injury. Western analysis confirmed the increase in AQP4 immunoreactivity observed in the injured tissue. The apparent increase in AQP4 immunoreactivity was likely due to de novo AQP4 protein synthesis, as most of the increased AQP4 immunoreactivity was found in the soluble (cytosolic) fraction. Our results demonstrate dynamic spatial and temporal changes in AQP4 expression that contribute to the molecular pathophysiology of PBI.
authors.affiliation: National Naval Medical Center, and Neurotrauma Laboratory, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, USA.
authors.forename: Chris J
authors.initials: CJ
authors.lastname: Neal
authors.forename: Eleanor Y
authors.initials: EY
authors.lastname: Lee
authors.forename: Andrea
authors.initials: A
authors.lastname: Gyorgy
authors.forename: James M
authors.initials: JM
authors.lastname: Ecklund
authors.forename: Denes V
authors.initials: DV
authors.lastname: Agoston
authors.forename: Geoffrey S F
authors.initials: GS
authors.lastname: Ling
mesh_terms: D000818:Animals; D051401:Aquaporin 4 / Q000096:biosynthesis*; D001253:Astrocytes / Q000378:metabolism / Q000473:pathology; D015153:Blotting, Western; D004195:Disease Models, Animal; D005904:Glial Fibrillary Acidic Protein / Q000096:biosynthesis; D020197:Head Injuries, Penetrating / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology*; D007150:Immunohistochemistry; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: C496032:Aqp4 protein, rat; D051401:Aquaporin 4; D005904:Glial Fibrillary Acidic Protein