title: Rapid loss of bone mass and strength in mice after abdominal irradiation.
abstract: Localized irradiation is a common treatment modality for malignancies in the pelvic-abdominal cavity. We report here on the changes in bone mass and strength in mice 7-14 days after abdominal irradiation. Male C57BL/6 mice of 10-12 weeks of age were given a single-dose (0, 5, 10, 15 or 20 Gy) or fractionated (3 Gy × 2 per day × 7.5 days) X rays to the abdomen and monitored daily for up to 14 days. A decrease in the serum bone formation marker and ex vivo osteoblast differentiation was detected 7 days after a single dose of radiation, with little change in the serum bone resorption marker and ex vivo osteoclast formation. A single dose of radiation elicited a loss of bone mineral density (BMD) within 14 days of irradiation. The BMD loss was up to 4.1% in the whole skeleton, 7.3% in tibia, and 7.7% in the femur. Fractionated abdominal irradiation induced similar extents of BMD loss 10 days after the last fraction: 6.2% in the whole skeleton, 5.1% in tibia, and 13.8% in the femur. The loss of BMD was dependent on radiation dose and was more profound in the trabecula-rich regions of the long bones. Moreover, BMD loss in the total skeleton and the femurs progressed with time. Peak load and stiffness in the mid-shaft tibia from irradiated mice were 11.2-14.2% and 11.5-25.0% lower, respectively, than sham controls tested 7 days after a single-dose abdominal irradiation. Our data demonstrate that abdominal irradiation induces a rapid loss of BMD in the mouse skeleton. These effects are bone type- and region-specific but are independent of radiation fractionation. The radiation-induced abscopal damage to the skeleton is manifested by the deterioration of biomechanical properties of the affected bone.
authors.affiliation: Department of Radiation Oncology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA. JiaDan@uams.edu
authors.forename: Dan
authors.initials: D
authors.lastname: Jia
authors.forename: Dana
authors.initials: D
authors.lastname: Gaddy
authors.forename: Larry J
authors.initials: LJ
authors.lastname: Suva
authors.forename: Peter M
authors.initials: PM
authors.lastname: Corry
mesh_terms: D000005:Abdomen; D000818:Animals; D001835:Body Weight / Q000528:radiation effects; D015519:Bone Density / Q000528:radiation effects*; D001842:Bone and Bones / Q000502:physiology* / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009928:Organ Specificity; D010012:Osteogenesis / Q000528:radiation effects; D013997:Time Factors