Transcriptional responses in various normal mouse tissues after 24 h following 4 MV photon beam irradiation using three partial body irradiation set-ups

Female BALB/c nude mice (n=3/group) were subjected to partial body irradiation under anesthesia using 2 Gy external photon (4 MV, nominal) irradiation. In group A, the collum (i.e. the thyroid) was irradiated; in group B, thorax+abdomen were irradiated, and in group C, collum+thorax+abdomen were irradiated. The control group (n=5) was anesthetized but not irradiated. At 24 h after treatment, the kidneys, liver, lungs, spleen, and thyroid were excised, flash-frozen, and stored at -80°C. Total RNA was extracted from homogenized tissue samples (kidney cortex and kidney medulla were treated separately) and subjected to expression analysis using RNA microarray technology. The study consisted of 3 irradiated groups with 3 animals each and one non-irradiated control group with 5 animals. Six tissues were analyzed per animal, each sample was analyzed individually, i.e. no samples were pooled.