Radiomodulation by Hoechst 33258 against radiation-induced damage in murine splenocytes

In this study modulatory effect of Hoechst 33258 on radiation induced membrane related signaling events which ultimately leads to apoptosis has been investigated. Splenocytes from Swiss albino mice were irradiated in air at room temperature in a gamma chamber (240 TBq 60Co Model 4000 A) at the dose-rate of 0.052 Gys(-1). Membrane lipid peroxidation, fluidity, specific activities of antioxidant enzymes, levels of nitric oxide, glutathione and apoptosis in presence and absence of different concentrations of Hoechst 33258 has been assayed. DNA binding activity of nuclear factor kappa B and activator protein-1 was also assayed by electrophoretic mobility shift assay. Modulatory effect of Hoechst 33258 was examined at 3 and 5 Gy using different concentrations (10, 20 and 30 microM). Hoechst 33258 was found to inhibit radiation induced peroxidative damage and fluidity and lowered the level of nitric oxide and apoptosis--as evident by DNA ladder assay and FACS, indicating free radicals scavenging potential. Dot plot diagramme clearly showed that 30 microM Hoechst 33258 caused 14% and 19% decrease in apoptotic cells at 3 Gy and 5 Gy of radiation respectively (compared to irradiated control group). Further DNA binding activity of nuclear factor kappa B and activator protein-1 was also inhibited but the antioxidant potential of the cells was enhanced. These findings support that Hoechst 33258 protects the cell from undergoing apoptosis. Hoechst 33258 may have interacted and has an ability to protect splenocytes against radiation induced apoptosis through modulation of membrane-related signaling events and antioxidant status.