Diffusion tensor imaging of brain abnormalities induced by prenatal exposure to radiation in rodents

Shigeyoshi Saito; Kazuhiko Sawada; Miwa Hirose; Yuki Mori; Yoshichika Yoshioka; Kenya Murase

doi:10.1371/journal.pone.0107368

Diffusion tensor imaging of brain abnormalities induced by prenatal exposure to radiation in rodents

PLoS One. 2014 Sep 9;9(9):e107368. doi: 10.1371/journal.pone.0107368. eCollection 2014.

Authors

Shigeyoshi Saito¹, Kazuhiko Sawada², Miwa Hirose², Yuki Mori³, Yoshichika Yoshioka³, Kenya Murase¹

Affiliations

¹ 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.
² Faculty of Medical and Health Sciences, Tsukuba International University, Tsuchiura, Japan.
³ 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.

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.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Brain Diseases / pathology*
Cerebral Cortex / pathology
Cerebral Cortex / radiation effects
Diffusion Tensor Imaging / methods
Female
Hippocampus / pathology
Hippocampus / radiation effects
Magnetic Resonance Imaging / methods
Male
Myelin Sheath / pathology
Myelin Sheath / radiation effects
Nervous System Malformations / pathology*
Pregnancy
Prenatal Exposure Delayed Effects / pathology
Pyramidal Cells / pathology
Pyramidal Cells / radiation effects
Radiation
Radiation Dosage
Rats
X-Rays / adverse effects*

Grants and funding

This work was supported by Grants-in-Aid (No. 24791299 and No. 24300167) for Scientific Research (Kakenhi) of the Japan Society for the Promotion of Science. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.