title: Magnetic resonance imaging of differential gray versus white matter injury following a mild or moderate hypoxic-ischemic insult in neonatal rats.
abstract: Selective white matter injury in the pre-mature infants suggests it has a greater susceptibility to hypoxia-ischemia. To investigate whether white matter injury would predominate following a mild hypoxic-ischemic insult, 7-day-old rats underwent either mild or moderate hypoxia-ischemia and magnetic resonance imaging 24 h later. Mild and moderate hypoxia-ischemia were produced by unilateral carotid artery occlusion plus exposure to hypoxia for either 45-50 or 90 min at ambient temperatures of 34.5 or 35.5 degrees C, respectively. Following mild hypoxia-ischemia, there was a significant increase in T(1) and T(2) within periventricular white matter (e.g. corpus callosum) in the hemisphere ipsilateral to the occlusion compared to that contralaterally and less of an increase within gray matter (e.g. cortex and striatum). This corresponded to relatively selective white matter injury detected histologically. Following a moderate hypoxia-ischemia, both gray and white matter was severely injured with marked increases in T(1) and T(2) occurring in both white and gray matter regions ipsilateral to the hypoxia-ischemia. We conclude that a mild insult, consisting of a short duration of hypoxia-ischemia at a slightly lower body temperature than a moderate hypoxic-ischemic insult, produces enhanced injury in white matter and a relative sparing of gray matter.
authors.affiliation: Institute for Biodiagnostics, National Research Council of Canada, B153, 3330 Hospital Dr. NW, Calgary, Alta., Canada T2N 4N1.
authors.forename: Min
authors.initials: M
authors.lastname: Qiao
authors.forename: Shuzhen
authors.initials: S
authors.lastname: Meng
authors.forename: Kathryn
authors.initials: K
authors.lastname: Scobie
authors.forename: Tadeusz
authors.initials: T
authors.lastname: Foniok
authors.forename: Ursula I
authors.initials: UI
authors.lastname: Tuor
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002540:Cerebral Cortex / Q000254:growth & development / Q000473:pathology*; D003337:Corpus Callosum / Q000254:growth & development / Q000473:pathology; D003342:Corpus Striatum / Q000254:growth & development / Q000473:pathology*; D005260:Female; D020925:Hypoxia-Ischemia, Brain / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009413:Nerve Fibers, Myelinated / Q000473:pathology*; D011247:Pregnancy; D051381:Rats; D017208:Rats, Wistar