Cerebral blood flow (CBF) acutely reduces in neonatal hypoxic-ischemic encephalopathy (HIE). Clinic studies have reported that severe CBF impairment can predict HIE outcomes in neonates. Herein, the present study uses a non-invasive 3D ultrasound imaging approach to evaluate the changes of CBF after HI insult, and explores the correlation between CBF alterations and HI-induced brain infarct in mouse pups. The neonatal HI brain injury was induced in postnatal day 7 mouse pups using the Rice-Vannucci model. Non-invasive 3D ultrasound imaging was conducted to image CBF changes with multiple frequencies on mouse pups before common carotid artery (CCA) ligation, immediately after ligation, and 0 or 24 hours after HI. Vascularity ratio of the ipsilateral hemisphere was acutely reduced after unilateral ligation of the CCA alone or in combination with hypoxia, and partially restored at 24 hours after HI. Moreover, regression analysis showed that the vascularity ratio of ipsilateral hemisphere was moderately correlated with brain infarct size 24 hours after HI, indicating that CBF reduction contributes to of HI brain injury. To further verify the association between CBF and HI-induced brain injury, a neuropeptide C-type natriuretic peptide (CNP) or PBS was intranasally administrated to the brain of mouse pups one hour after HI insult. Brain infarction, CBF imaging and long-term neurobehavioral tests were conducted. The result showed that intranasal administration of CNP preserved ipsilateral CBF, reduced the infarct size, and improved neurological function after HI brain injury. Our findings suggest that CBF alteration is an indicator for neonatal HI brain injury, and 3D ultrasound imaging is a useful non-invasive approach for assessment of HI brain injury in mouse model.
High altitude (> 2500 meters) during pregnancy reduces oxygen delivery to the fetus (i.e., gestational hypoxia), causing abnormal fetal lung development. The pulmonary arteries become thicker and less functional, increasing the risk of pulmonary hypertension, which is a multiorgan disease that promotes right heart failure and under five‐years mortality rate. Our previous work showed endoplasmic reticulum stress and metabolomic alterations in fetal sheep pulmonary arteries indicative of an unregulated inflammatory response after gestational hypoxia. To understand the relationships between inflammation, vascular remodeling, and pulmonary arterial hypertension development, we examined the omic links between the pulmonary arteries and plasma exosomes in fetal sheep exposed to high altitude (3801 meters) for the majority of the pregnancy (110+ days out of 138‐141 days of pregnancy). Specifically, metabolomics and proteomic analyses from the pulmonary arteries and transcriptomic analysis of plasma exosomes were integrated from fetal sheep to understand the mechanisms driving this multiorgan disease. Sixteen miRNAs and 75 proteins were differentially expressed between normoxic and hypoxic samples. Gestational hypoxia resulted in significant changes in 90 metabolites in fetal pulmonary arteries. These results show exosomal microRNA are linked with pulmonary artery proteins and metabolites important to cell membrane composition which might explain their role in the facilitation of changes in vascular remodeling, inflammation, and cell signaling. Top canonical pathways noted in omics data integration were acute phase response signaling, atherosclerosis signaling, FXR/RXR activation, intrinsic prothrombin activation pathway, and LXR/RXR activation. This multi‐omics study illustrates the intricacy of complex adaptations that occur in the fetal sheep lung in response to gestational hypoxia.
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