White matter damage precedes that in gray matter despite similar magnetic resonance imaging changes following cerebral hypoxia-ischemia in neonatal rats.
We hypothesized that the cerebral injury produced by hypoxia-ischemia (HI) in neonatal rats would differ in white compared with gray matter as detected histologically or with magnetic resonance (MR) imaging methods. Maps of T2 and the apparent diffusion coefficient (ADC) of water were acquired in 1-week-old rats at times prior to cerebral HI (right carotid artery occlusion plus 1.5 h of hypoxia), within the last 5-10 min of HI, and 1 h or 24 h after HI. Near the end of HI, ADC decreased and T2 increased in both cortical gray and subcortical white matter within the cingulum of the HI hemisphere. One hour after HI, ADC partially recovered, but T2 remained increased and then increased further by 24 h post-HI. In contrast to the similar MR responses in white and gray matter, histological evidence for irreversible cell damage occurred in white matter earlier than in gray matter within the HI hemisphere. At 1 h post-HI, rarefied or disrupted nerve fibers and an increase in TUNEL-positive cells were observed within white matter in the cingulum, whereas neurons within the cortical gray matter appeared normal. By 24 h post-HI, damage was apparent in both white and gray matter. Thus, MR imaging detected acute tissue edema following cerebral HI in both gray and white matter but did not distinguish between the early irreversible tissue injury detected histologically in white but not gray matter in this rather severe model of neonatal encephalopathy.
Meng
Shuzhen
S
Institute for Biodiagnostics (West), National Research Council of Canada, 3330 Hospital Drive, NW Calgary, AB, T2N 4N1, Canada.
Qiao
Min
M
Foniok
Tadeusz
T
Tuor
Ursula I
UI
D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D001929:Brain Edema / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D002452:Cell Count; D016923:Cell Death / Q000502:physiology; D002540:Cerebral Cortex / Q000473:pathology* / Q000503:physiopathology; D002544:Cerebral Infarction / Q000473:pathology* / Q000503:physiopathology; D004058:Diffusion; D004195:Disease Models, Animal; D006801:Humans; D020925:Hypoxia-Ischemia, Brain / Q000473:pathology* / Q000503:physiopathology; D020287:In Situ Nick-End Labeling; D007231:Infant, Newborn; D007969:Leukomalacia, Periventricular / Q000473:pathology / Q000503:physiopathology; D009410:Nerve Degeneration / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D009413:Nerve Fibers, Myelinated / Q000378:metabolism / Q000473:pathology*; D051381:Rats; D017208:Rats, Wistar