Exposure to radiation is increasing in a variety of settings including space exploration, diagnostic medical procedures and radiotherapy. Cells of the hematopoietic system, such as white blood cells (WBC), are especially sensitive to radiation and their decline can result in Acute Radiation Syndrome (ARS). Radiotherapy is often used for cancers of the central nervous system (CNS), but includes the risk for normal tissue damage, often leading to cognitive impairment. The literature suggests that tetracyclines can be radioprotectors of the hematopoietic system with potential utility in radiation emergencies and anticancer radiotherapy. Minocycline, a semisynthetic tetracycline derivative, has anti-inflammatory, free radical scavenging, anti-apoptotic and antiangiogenic properties with exceptional penetration into the CNS. These qualities make it a viable candidate for use in combination with radiotherapy for CNS tumors as a normal tissue radioprotectant and for hematopoietoc recovery following whole-body irradiation. This study was undertaken to determine the potential of minocycline as a radioprotective agent of the hematopoietic system and CNS in response to whole-body irradiation with 1, 2 and 3 Gy (Î³-rays). C57BL/6 mice were injected with minocycline, 5 times beginning immediately before irradiation. Spleen, blood and brain were collected on days 4 and 32 post-irradiation. WBC and other cell populations were determined in the blood and spleen while cytokines were quantified in CD3-activated splenocytes and homogenized brain supernatants. We also evaluated the impact of minocycline on DNA synthesis and viability of human glioblastoma cells versus astrocytes and microglia. Minocycline increased counts and percentages of splenic macrophages, granulocytes, natural killer (NK), T and CD8+ T cells on day 4 and B cells on day 32. Minocycline upregulated interleukin-1Î± (IL-1Î±) which is radioprotective, as well as granulocytemacrophage colony stimulating factor (GM-CSF) and G-CSF that accelerate neutrophil recovery at both time points post-exposure. Minocycline reversed the radiation-induced IL-10 decrease in the brain on day 4 while increasing vascular endothelial growth factor (VEGF), and lowering IL-1Î² on day 32. The drug did not protect glioblastoma cell lines from radiation but increased the viability of astrocytes at lower doses. These data support further testing of minocycline to counteract radiation insult to the hematopoietic system and CNS.
School of Medicine
Gridley, Daila S.
Doctor of Philosophy (PhD)
Year Degree Awarded
Date (Title Page)
Library of Congress/MESH Subject Headings
Diagnostic Techniques and Procedures; Radiation Effects; Radiobiology;
Subject - Local
Minocycline, Radioprotectants, Diagnostic Medical Procedures, Radiotherapy, Tetracyclines, Radiation Insult
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Mehrota, Shalini, "Analysis of Minocycline as a Radioprotectant" (2012). Loma Linda University Electronic Theses, Dissertations & Projects. 87.
Loma Linda University Electronic Theses & Dissertations
Loma Linda University. Del E. Webb Memorial Library. University Archives