Prenatal ionizing radiation-induced apoptosis of the developing murine brain with special references to the expression of some proteins.
Apoptosis induced by ionizing irradiation of the developing mouse brain was investigated by using histology, analysis of DNA fragmentation on agarose gel and electron microscopy. A TUNEL-labeled index (L.I.) was calculated from the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL) assay in 4 specific regions, cortical plate, intermediate zone, subependymal zone, and subependymal germinal matrix. The kinetics of apoptosis associated protein was examined by western blotting and immunofluorescence. C57BL/6J mice pregnant on embryonic day 14 (E14) were exposed to a single dose of 1.5-Gy irradiation. Irradiated fetal brains at E15 and E17 showed extensive apoptosis with morphological characteristics. In all 4 regions, L.I. was greater in irradiated brains than in control brains at E15 and E17. Most of TUNEL-labeled cells expressed a mature neuronal marker (NeuN) and Bax protein, which is up-regulated in irradiation-induced apoptosis. Ionizing radiation moderately enhanced expression of Bax, Bcl-xL, and Cpp32 proteins. Postnatal irradiated mice showed microencephaly as compared to age-matched mice and the weight of whole body including brain decreased moderately.
Kitamura
M
M
First Division, Department of Pathology, Kobe University School of Medicine.
Itoh
K
K
Matsumoto
A
A
Hayashi
Y
Y
Sasaki
R
R
Imai
Y
Y
Itoh
H
H
D000818:Animals; D017209:Apoptosis / Q000528:radiation effects*; D015153:Blotting, Western; D001921:Brain / Q000196:embryology* / Q000528:radiation effects* / Q000648:ultrastructure; D053148:Caspase 3; D020169:Caspases / Q000032:analysis / Q000235:genetics; D053938:DNA Fragmentation; D005260:Female; D005455:Fluorescent Antibody Technique; D015870:Gene Expression / Q000528:radiation effects*; D005865:Gestational Age; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D066298:In Vitro Techniques; D007700:Kinetics; D051379:Mice; D008810:Mice, Inbred C57BL; D008831:Microcephaly / Q000209:etiology; D008854:Microscopy, Electron; D009929:Organ Size; D011247:Pregnancy; D011518:Proto-Oncogene Proteins / Q000032:analysis / Q000235:genetics; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis / Q000235:genetics; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein
C494827:Bax protein, mouse; C494812:Bcl2l1 protein, mouse; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases