Abstract: ObjectiveTo investigate the injuries of intestinal mitochondria induced by different doses of whole-body radiation
in Tibet minipigs. MethodsEighteen Tibet minipigs were randomized into5radiation groups (n=3) and a control group (n=3).
The minipigs in the radiation groups were subject to a total body X-ray radiation at2, 5, 8, 11, or 14Gy, and72h after the
exposure, the mRNA expressions of the intestinal mitochondrial genes were examined using RT-PCR. The changes in the
respiratory chain complexes I-IV and the respiratory functions of succinate and NADH were assayed, and the intestinal
ultrastructures were observed using transmission electron microscopy (TEM) following the exposures.ResultsCompared with
those in the control group, the expression levels of the related mitochondrial genes, the activities of the respiratory chain
complexes and the function of the respiratory chain were significantly lowered in the radiation groups. At the doses
below8Gy, the exposures caused significant reduction in the measurements as the radiation doses increased, but at higher
doses, these measurements showed no further reductions. Ultrastructurally, exposures at2and5Gy caused mitochondrial
expansion and mild reduction of the density, whereas radiation at8Gy or greater resulted in vacuolar changes and obvious
expansion of the mitochondria with damages of the mitochondrial cristae and membranes.ConclusionBelow the doses of8
Gy, intestinal mitochondrial damages in the minipigs increase with the radiation dose, but at higher doses, the damages do not
further increase with the radiation dose.