title: Cerebral blood flow heterogeneity in preterm sheep: lack of physiologic support for vascular boundary zones in fetal cerebral white matter.
abstract: Periventricular white matter (PVWM) injury is the leading cause of neurologic disability in survivors of prematurity. To address the role of ischemia in PVWM and cerebral cortical injury, we hypothesized that immaturity of spatially distal vascular 'end zones' or 'border zones' predisposes PVWM to greater decreases in cerebral blood flow (CBF) than more proximal structures. We quantified regional CBF with fluorescently labeled microspheres in 0.65 gestation fetal sheep in histopathologically defined three-dimensional regions by post hoc digital dissection and coregistration algorithms. Basal flow in PVWM was significantly lower than in gyral white matter and cortex, but was equivalent in superficial, middle, and deep PVWM. Absolute and relative CBF (expressed as percentage of basal) did not differ significantly during ischemia or reperfusion between PVWM, gyral white matter, or cortex. Moreover, CBF during ischemia-reperfusion was equivalent in three adjacent PVWM levels and was not consistent with the magnitude of severity of PVWM injury, defined by TUNEL (terminal deoxynucleotidyltransferase-mediated dUPT nick end labeling) staining. However, the magnitude of ischemia was predicted by the severity of discrete cortical lesions. Hence, unlike cerebral cortex, unique CBF disturbances did not account for the distribution of PVWM injury. Previously defined cellular maturational factors, thus, appear to have a greater influence on PVWM vulnerability to ischemic injury than the presence of immature vascular boundary zones.
authors: Department of Pediatrics, Oregon Health & Science University, Portland, Oregon, USA.
authors: Melissa M
authors: MM
authors: McClure
authors: Art
authors: A
authors: Riddle
authors: Mario
authors: M
authors: Manese
authors: Ning Ling
authors: NL
authors: Luo
authors: Dawn A
authors: DA
authors: Rorvik
authors: Katherine A
authors: KA
authors: Kelly
authors: Clyde H
authors: CH
authors: Barlow
authors: Jeffrey J
authors: JJ
authors: Kelly
authors: Kevin
authors: K
authors: Vinecore
authors: Colin T
authors: CT
authors: Roberts
authors: A Roger
authors: AR
authors: Hohimer
authors: Stephen A
authors: SA
authors: Back
mesh_terms: D000818:Animals; D002540:Cerebral Cortex / Q000098:blood supply* / Q000196:embryology / Q000473:pathology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003337:Corpus Callosum / Q000098:blood supply* / Q000196:embryology / Q000473:pathology; D004569:Electroencephalography; D004827:Epilepsy / Q000473:pathology / Q000503:physiopathology; D005260:Female; D005865:Gestational Age; D020925:Hypoxia-Ischemia, Brain / Q000473:pathology* / Q000503:physiopathology*; D020287:In Situ Nick-End Labeling; D008863:Microspheres; D009413:Nerve Fibers, Myelinated / Q000473:pathology* / Q000502:physiology; D009836:Oligodendroglia / Q000473:pathology / Q000502:physiology; D011237:Predictive Value of Tests; D011247:Pregnancy; D015427:Reperfusion Injury / Q000473:pathology / Q000503:physiopathology; D012720:Severity of Illness Index; D012756:Sheep