Long-term changes in rat hematopoietic and other physiological systems after high-energy iron ion irradiation.
OBJECTIVE
To assess the long-term consequences of high-linear energy transfer (LET) iron ion radiation on immune and other critical body systems in the context of assessing potential effects astronauts may experience during exploratory missions.


METHODS
Sprague-Dawley rats were nearly whole-body irradiated with 56-Fe (5 GeV/n) to total doses of 0, 1, 2, and 4 Gray (Gy) and euthanized 9 months post-exposure for analyses.


RESULTS
Irradiated groups consistently had low body mass. Numbers of circulating white blood cells (WBC), lymphocytes and monocytes were lower in the 2 Gy group compared to 0 Gy (p < 0.05); a trend for low granulocytes was also noted. Red blood cell counts, hemoglobin, and hematocrit were decreased in irradiated animals (p < 0.05), whereas platelet counts and volume were unaffected. In the spleen, WBC counts and DNA synthesis by T cells were similar among groups and there were no differences in secreted interferon-gamma and interleukin-6. However, trends were noted for increased splenocyte capacity to secrete tumor necrosis factor-alpha and increased level of vascular endothelial cell growth factor in plasma. One or more of the irradiated groups had significant (p < 0.05) aberrations in several blood chemistry parameters associated with liver and kidney function.


CONCLUSIONS
The data show that exposure to 56-Fe radiation induced pathological changes in important body systems long after exposure.
Gridley
Daila S
DS
Department of Radiation Medicine, Loma Linda University and Medical Center, Loma Linda, CA 92354, USA. dgridley@dominion.llumc.edu
Obenaus
Andre
A
Bateman
Ted A
TA
Pecaut
Michael J
MJ
D000818:Animals; D016207:Cytokines / Q000097:blood; D004307:Dose-Response Relationship, Radiation; D006410:Hematopoiesis / Q000502:physiology / Q000528:radiation effects*; D007371:Interferon-gamma / Q000097:blood; D015850:Interleukin-6 / Q000097:blood; D007477:Ions; D007501:Iron; D007668:Kidney / Q000502:physiology / Q000528:radiation effects*; D007962:Leukocytes / Q000166:cytology / Q000502:physiology / Q000528:radiation effects*; D018499:Linear Energy Transfer; D051381:Rats; D017207:Rats, Sprague-Dawley; D013154:Spleen / Q000502:physiology / Q000528:radiation effects*; D013601:T-Lymphocytes / Q000166:cytology / Q000502:physiology / Q000528:radiation effects; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000097:blood; D042461:Vascular Endothelial Growth Factor A / Q000097:blood; D014916:Whole-Body Irradiation / Q000009:adverse effects*
D016207:Cytokines; D015850:Interleukin-6; D007477:Ions; D014409:Tumor Necrosis Factor-alpha; D042461:Vascular Endothelial Growth Factor A; D007371:Interferon-gamma; D007501:Iron