title: Diffusion tensor imaging of brain abnormalities induced by prenatal exposure to radiation in rodents.
abstract: We assessed brain abnormalities in rats exposed prenatally to radiation (X-rays) using magnetic resonance imaging (MRI) and histological experiments. Pregnant rats were divided into 4 groups: the control group (n = 3) and 3 groups that were exposed to different radiation doses (0.5, 1.0, or 1.5 Gy; n = 3 each). Brain abnormalities were assessed in 32 neonatal male rats (8 per group). Ex vivo T2-weighted imaging and diffusion tensor imaging (DTI) were performed using 11.7-T MRI. The expression of markers of myelin production (Kluver-Barrera staining, KB), nonpyramidal cells (calbindin-D28k staining, CaBP), and pyramidal cells (staining of the nonphosphorylated heavy-chain neurofilament SMI-32) were histologically evaluated. Decreased brain volume, increased ventricle volume, and thinner cortices were observed by MRI in irradiated rats. However, no abnormalities in the cortical 6-layered structure were observed via KB staining in radiation-exposed rats. The DTI color-coded map revealed a dose-dependent reduction in the anisotropic signal (vertical direction), which did not represent reduced numbers of pyramidal cells; rather, it indicated a signal reduction relative to the vertical direction because of low nerve cell density in the entire cortex. We conclude that DTI and histological experiments are useful tools for assessing cortical and hippocampal abnormalities after prenatal exposure to radiation in rats.
authors.affiliation: Department of Medical Physics and Engineering, Division of Medical Technology and Science, Faculty of Health Science, Graduate School of Medicine, Osaka University, Osaka, Japan; Center for Information and Neural Networks (CiNet), National Institute of Information and Communications Technology, and Osaka University, Osaka, Japan.
authors.forename: Shigeyoshi
authors.initials: S
authors.lastname: Saito
authors.affiliation: Faculty of Medical and Health Sciences, Tsukuba International University, Tsuchiura, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Sawada
authors.affiliation: Faculty of Medical and Health Sciences, Tsukuba International University, Tsuchiura, Japan.
authors.forename: Miwa
authors.initials: M
authors.lastname: Hirose
authors.affiliation: Biofunctional Imaging Lab, Immunology Frontier Research Center (WPI-IFReC), Osaka University, Osaka, Japan; Center for Information and Neural Networks (CiNet), National Institute of Information and Communications Technology, and Osaka University, Osaka, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Mori
authors.affiliation: Biofunctional Imaging Lab, Immunology Frontier Research Center (WPI-IFReC), Osaka University, Osaka, Japan; Center for Information and Neural Networks (CiNet), National Institute of Information and Communications Technology, and Osaka University, Osaka, Japan.
authors.forename: Yoshichika
authors.initials: Y
authors.lastname: Yoshioka
authors.affiliation: Department of Medical Physics and Engineering, Division of Medical Technology and Science, Faculty of Health Science, Graduate School of Medicine, Osaka University, Osaka, Japan; Center for Information and Neural Networks (CiNet), National Institute of Information and Communications Technology, and Osaka University, Osaka, Japan.
authors.forename: Kenya
authors.initials: K
authors.lastname: Murase
mesh_terms: D000818:Animals; D001927:Brain Diseases / Q000473:pathology*; D002540:Cerebral Cortex / Q000473:pathology / Q000528:radiation effects; D056324:Diffusion Tensor Imaging / Q000379:methods; D005260:Female; D006624:Hippocampus / Q000473:pathology / Q000528:radiation effects; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D009186:Myelin Sheath / Q000473:pathology / Q000528:radiation effects; D009421:Nervous System Malformations / Q000473:pathology*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000473:pathology; D017966:Pyramidal Cells / Q000473:pathology / Q000528:radiation effects; D011827:Radiation; D011829:Radiation Dosage; D051381:Rats; D014965:X-Rays / Q000009:adverse effects*