High levels of apoptosis induced by total body irradiation in mice fed a low protein-low vitamin E diet.

Apoptosis in response to total body irradiation (TBI) in mice fed four kinds of diets was assessed. Male mice were fed a low protein-low vitamin E diet, a low protein-basal vitamin E diet, a basal protein-low vitamin E diet or a basal protein-basal vitamin E diet for 2 weeks, then received TBI at a dose of 0, 1 or 4 Gy, and were sacrificed 4 h after TBI. Apoptosis was assessed according to the appearance of DNA fragmentation patterns [DNA laddering and positive in situ end-labeling by terminal transferase (TUNEL) assay] and apoptotic index (AI). Electrophoresis of DNA from the spleen in the groups that did not receive TBI showed no cleavage, whereas that of DNA in the groups with 4 Gy of TBI displayed a ladder pattern, indicative of internucleosomal cleavage characteristic of apoptosis. In the groups with 4 Gy of TBI, apoptosis was enhanced in the low protein-low vitamin E group.