title: Effect of acute and fractionated irradiation on hippocampal neurogenesis.
abstract: Ionizing radiation has become an inevitable health concern emanating from natural sources like space travel and from artificial sources like medical therapies. In general, exposure to ionizing radiation such as γ-rays is one of the methods currently used to stress specific model systems. In this study, we elucidated the long-term effect of acute and fractionated irradiation on DCX-positive cells in hippocampal neurogenesis. Groups of two-month-old C57BL/6 female mice were exposed to whole-body irradiation at acute dose (5 Gy) or fractional doses (1 Gy × 5 times and 0.5 Gy × 10 times). Six months after exposure to γ-irradiation, the hippocampus was analyzed. Doublecortin (DCX) immunohistochemistry was used to measure changes of neurogenesis in the subgranular zone (SGZ) of the hippocampal dentate gyrus (DG). The number of DCX-positive cells was significantly decreased in all acute and fractionally irradiation groups. The long-term changes in DCX-positive cells triggered by radiation exposure showed a very different pattern to the short-term changes which tended to return to the control level in previous studies. Furthermore, the number of DCX-positive cells was relatively lower in the acute irradiation group than the fractional irradiation groups (approximately 3.6-fold), suggesting the biological change on hippocampal neurogenesis was more susceptible to being damaged by acute than fractional irradiation. These results suggest that the exposure to  γ-irradiation as a long-term effect can trigger biological responses resulting in the inhibition of hippocampal neurogenesis.
authors.affiliation: Division of Biotechnology, Advanced Radiation Technology Institute-ARTI, Korea Atomic Energy Research Institute-KAERI, 1266, Sinjeong-dong, Jeongeup, Jeonbuk 580-185, Korea.
authors.forename: Min-Kyoung
authors.initials: MK
authors.lastname: Park
authors.forename: Seolhwa
authors.initials: S
authors.lastname: Kim
authors.forename: Uhee
authors.initials: U
authors.lastname: Jung
authors.forename: Insub
authors.initials: I
authors.lastname: Kim
authors.forename: Jin Kyu
authors.initials: JK
authors.lastname: Kim
authors.forename: Changhyun
authors.initials: C
authors.lastname: Roh
mesh_terms: D000818:Animals; D018891:Dentate Gyrus / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D000089622:Doublecortin Domain Proteins; D000089662:Doublecortin Protein; D005260:Female; D005720:Gamma Rays; D051379:Mice; D008810:Mice, Inbred C57BL; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D055495:Neurogenesis / Q000528:radiation effects*; D009479:Neuropeptides / Q000378:metabolism; D014916:Whole-Body Irradiation
chemical_list: C000714847:Dcx protein, mouse; D000089622:Doublecortin Domain Proteins; D000089662:Doublecortin Protein; D008869:Microtubule-Associated Proteins; D009479:Neuropeptides