title: Low-dose radiation modifies skin response to acute gamma-rays and protons.
abstract: The goal of the present study was to obtain pilot data on the effects of protracted low-dose/low-dose-rate (LDR) γ-rays on the skin, both with and without acute gamma or proton irradiation (IR). Six groups of C57BL/6 mice were examined: a) 0 Gy control, b) LDR, c) Gamma, d) LDR+Gamma, e) Proton, and f) LDR+Proton. LDR radiation was delivered to a total dose of 0.01 Gy (0.03 cGy/h), whereas the Gamma and Proton groups received 2 Gy (0.9 Gy/min and 1.0 Gy/min, respectively). Assays were performed 56 days after exposure. Skin samples from all irradiated groups had activated caspase-3, indicative of apoptosis. The significant (p<0.05) increases in immunoreactivity in the Gamma and Proton groups were not present when LDR pre-exposure was included. However, the terminal deoxynucleotidyl transferase dUTP nick-end labeling assay for DNA fragmentation and histological examination of hematoxylin and eosin-stained sections revealed no significant differences among groups, regardless of radiation regimen. The data demonstrate that caspase-3 activation initially triggered by both forms of acute radiation was greatly elevated in the skin nearly two months after whole-body exposure. In addition, LDR γ-ray priming ameliorated this response.
authors.affiliation: Chan Shun Pavilion, Room A-1010, 11175 Campus Street, Loma Linda Univesity, Loma Linda, CA 92354, U.S.A. xmao@llu.edu.
authors.forename: Xiao Wen
authors.initials: XW
authors.lastname: Mao
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Pecaut
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Cao
authors.forename: Maria
authors.initials: M
authors.lastname: Moldovan
authors.forename: Daila S
authors.initials: DS
authors.lastname: Gridley
mesh_terms: D000818:Animals; D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism; D053938:DNA Fragmentation; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005720:Gamma Rays; D051379:Mice; D008810:Mice, Inbred C57BL; D011522:Protons; D011833:Radiation Injuries, Experimental / Q000201:enzymology*; D011836:Radiation Tolerance / Q000528:radiation effects; D012867:Skin / Q000201:enzymology / Q000473:pathology / Q000528:radiation effects*; D014916:Whole-Body Irradiation
chemical_list: D011522:Protons; C505409:Casp3 protein, mouse; D053148:Caspase 3
keywords: DNA fragmentation; Dermis; apoptosis; caspase-3; skin