Radioprotection by tempol: Studies on tissue antioxidant levels, hematopoietic and gastrointestinal systems, in mice whole body exposed to sub- lethal doses of gamma radiation

Ionizing radiation induces the production of reactive oxygen species (ROS), which play an important causative role in cell death. Wholebody exposure of mice to gamma radiation leads to diminution of tissue antioxidant defense systems; increases the peroxidative damage to membrane lipids and damages the haematopoietic and gastrointestinal systems. Tempol (TPL), a cell membranepermeable amphilite nitroxide, shown to protect against cell injury caused by ROS was studied for its radioprotective effects. Animals were administered with TPL at doses of 100 or 200 mg/kg body weight p.o 10 minutes prior to sub- lethal doses (4 or 6 Gy) of whole body gamma radiation exposure. Tempol prevented the radiation induced depletion in RBC and total WBC counts, glutathione content in blood and bone marrow cellularity. TPL also protected the tissue antioxidant system and membrane lipids from the radiation-induced damages. An enhanced spleen colony formation and spleen weight recovery were also observed in radiation exposed mice administered with TPL. The compound also protected the epithelial cells of the gastrointestinal tract from the radiation-induced structural alterations. These preclinical data indicate that TPL may have its potential as a radioprotector during radiation exposure scenarios.