Effect of umbilical cord occlusion on behavior and neurohistology in sheep fetus.

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Objectives : Neurologic deficit in children can be attributed to prenatal events and asphyxial insults. In human pregnancies near term, intermittent 'variable type' fetal heart rate (FHR) decelerations are seen in 5% and can be associated with umbilical cord occlusion (UCO). Effect of intermittent UCO on neurohistology in fetus is determined. Clinical detection for hypo-perfusion of the fetal brain is also investigatedMethods : 14 chronically instrumented fetal sheep (experimental, n=7, Control, n=7) at 0.8 gestation were studied over 4 days with UCOs by complete inflation of an occluder cuff (duration 90 seconds) every 30 minutes for 3 to 5 hours each day. Animals were then euthanized and the fetal brains were prepared for subsequent histology and immunostaining for myelin(SCR), astrocytes(GFAP), and activated microglia(HLADR). Brain injury was scored by a neuropathologist, based on the severity of injury by histopathology and changes in immunostaining ; 0-normal, 1-minimal, 2-mild/ea … More rly, 3-moderate to severe/advanced. We also studied the circulatory change by using blood pressure and SpO_2 charges in goat fetus. These experiments were conducted in the Department of Veterinary Medicine of Kagoshima University and Department of Obstetrics and Gynecology of Western Ontario University, Canada.Results : Fetal PO_2 decreased from 24.0±0.5 to 6.7±0.8mmHg whereas change of PH was from 7.36 to 7.31. All the experiment group showed minimal injury (increased staining of GFR and/or HLADR) or mild injury (plus in ischemic neurons in cortex). Brain injury score for controls was significantly lower, averaging 0.4±0.25(p<0.01) with one animals having minimal injury and 1.6±0.20 in experimental group.Conclusions : We conclude that intermittent UCO can result in neuropathological change in the cortical and subcortical white and gray matters. We speculate that intermittent UCO may give rise to postnatal neurologic deficit. New technique to detect brain hypo-perfusion is required in clinical settings. Less