Chronic fetal hypoxia affects axonal maturation in guinea pigs during development: A longitudinal diffusion tensor imaging and T2 mapping study. Issue 3 (15th December 2014)

• Record Type: Journal Article
• Authors: Kim, Jieun; Choi, In‐Young; Dong, Yafeng; Wang, Wen‐Tung; Brooks, William M.; Weiner, Carl P.; Lee, Phil
• Is Part Of: Journal of magnetic resonance imaging. Volume 42:Issue 3(2015)
• Page Start: 658
• Page End: 665
• Publication Date: 2014-12-15
• Subjects: Magnetic resonance imaging -- Periodicals; 616
• DOI: 10.1002/jmri.24825
• Languages: English
• ISSNs: 1053-1807

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="jmri24825-sec-0001" sec-type="section"> <title>Purpose</title> <p>To investigate the impact of chronic hypoxia on neonatal brains, and follow developmental alterations and adaptations noninvasively in a guinea pig model. Chronic hypoxemia is the prime cause of fetal brain injury and long‐term sequelae such as neurodevelopmental compromise, seizures, and cerebral palsy.</p> </sec> <sec id="jmri24825-sec-0002" sec-type="section"> <title>Materials and Methods</title> <p>Thirty guinea pigs underwent either normoxic and hypoxemic conditions during the critical stage of brain development (0.7 gestation) and studied prenatally (<italic>n</italic> = 16) or perinatally (<italic>n</italic> = 14). Fourteen newborns (7 hypoxia and 7 normoxia group) were scanned longitudinally to characterize physiological and morphological alterations, and axonal myelination and injury using in vivo diffusion tensor imaging (DTI), <italic>T</italic><sub>2</sub> mapping, and <italic>T</italic><sub>2</sub>‐weighted magnetic resonance imaging (MRI). Sixteen fetuses (8 hypoxia and 8 normoxia) were studied ex vivo to assess hypoxia‐induced neuronal injury/loss using Nissl staining and quantitative reverse transcriptase polymerase chain reaction methods.</p> </sec> <sec id="jmri24825-sec-0003" sec-type="section"> <title>Results</title> <p>Developmental brains in the hypoxia group showed lower fractional anisotropy in the corpus callosum (−12%, <italic>P</italic> = 0.02) and lower <italic>T</italic><sub>2</sub> values in the hippocampus (−16%, <italic>P</italic> = 0.003) compared with the normoxia group with no differences in the cortex (<italic>P</italic> > 0.07), indicating vulnerability of the hippocampus and cerebral white matter during early development. Fetal guinea pig brains with chronic hypoxia demonstrated an over 10‐fold increase in expression levels of hypoxia index genes such as erythropoietin and HIF‐1α, and an over 40% reduction in neuronal density, confirming prenatal brain damage.</p> </sec> <sec id="jmri24825-sec-0004" sec-type="section"> <title>Conclusion</title> <p>In vivo MRI measurement, such as DTI and <italic>T</italic><sub>2</sub> mapping, provides quantitative parameters to characterize neurodevelopmental abnormalities and to monitor the impact of prenatal insult on the postnatal brain maturation of guinea pigs. J. Magn. Reson. Imaging 2015;42:658–665.</p> </sec> </abstract>