Low-dose radiation induced modification of ROS and apoptosis in thymocytes of whole body irradiated mice

Whole body irradiation (WBI) to a single dose of 3 Gy of γ-rays has earlier been shown in our laboratory to induce thymic lymphoma (TL) after 4-5 months in Swiss mice. The tumour induction was significantly found suppressed when animals were pre-exposed to radiation doses in the range of a few cGy. Recent research efforts have been focused to investigate the molecular mechanism of these observations. In vitro studies on thymocytes from irradiated mice have shown a radiation dose (1-5 Gy) and post-irradiation (3 Gy) time dependent increase in intracellular reactive oxygen species (ROS) as measured by 2,7-dichlorodihydroflurescein diacetate (DCH-FDA) and enhanced apoptosis as measured by fluorescent probe, merocyanine-540 (MC-540). Typically, a five-fold increase in ROS and apoptosis was observed in thymocytes collected 30 minutes after exposure of mice to a dose of 5 Gy suggesting substantial up-regulation of ROS in cells after exposure of animal to moderate oxidative stress. It was further found that incr...