RESUMO
Clinical and experimental studies of the early and late effects of radiation on cells have led to optimization of radiotherapy schedules and to more precise modes of radiation delivery, radiation induced-injury on normal tissue can present either during or after the completion of radiotherapy. Early effects of small accumulated doses of gamma-irradiation in mice were studied at the present work. Fifty four mice were classified as the following negative control group I, distilled water subgroup Iia, etodolac subgroup IIb, subgroup IIIa was irradiated by accumulated dose of 0.5 Gy, subgroup IIIb received etodolac half an our pre-0.5 Gy irradiation, subgroup IVa was irradiated y accumulated dose of 1Gy, subgroup Ivb received etodolac pre-1 Gy irradiation, suroup Va was irradicated by accumulated dose of 2 Gy and the last subgroup Vb received etodolac pre-2 Gy irradiation. Analysis of bone marrow and jejunal cell cycle kinetic was carried out using flowcytometery and histochemical studies. The results revealed hat there was significant dose-dependant alternation of cell cycle kinetic of bone marrow and jejunal samples in the form of increase in GI and CVGI and decrease in percent SPE, percent G2 and PI. Mitotic delay, reduction in DNA content and chromatin condensation underneath the nuclear membrane of the cells in both cypts and villi of the jejunal sections could be also observed. Etodolac adminisration to the mice half an hour pre-irradiation could offer a great radioprotective effect. Research opportunities may help future clinical application of selective cyclooxygenase-2 inhibitors as chemopreventive drugs