Measurement of apoptotic fragments in growing hair follicles following γ-ray irradiation in mice

The usefulness of apoptotic fragments assay for investigating radiation exposure response of hair follicles was examined. Frequency was defined as the ratio of the total number of apoptotic fragments to the number of hair follicles per section examined. The curve of dose-effect relationship for the data of apoptotic fragments was obtained by fitting the linear-quadratic model y = a + bD + cD². When plotting on a lineal scale against radiation dose, the line of best fit was y = (0.549 + 1.775) + (3.578 + 1.236)D + (-0.124 + 0.139)D². The dose-response curves were linear-quadratic and a significant relationship was found between the frequency of apoptotic fragments and dose. The morphological findings of the irradiated groups were typical apoptotic fragments in the matrix region of hair follicles, but the spontaneous occurence of apoptotic fragments was not observed. Since the apoptotic fragment assay is simple and reproducible in the whole body irradiation range of 0.5 to 8 Gy, it may be a good tool for evaluating the dose response of low dose radiation in vivo and provide a potentially valuable biological dosimeter for dose distribution determinations following accidental exposure.