Activation of NF-κB in bone marrow cells of BALB/cJ mice following exposure in vivo to low doses of ¹³⁷Cs γ-rays

We measured levels of NF-κB activation in bone marrow (BM) cells collected at 1 and 4 h from male BALB/cJ mice (10-12 weeks old) given a whole body dose of 0, 0.05, 0.1 and 1 Gy of ¹³⁷Cs γ-rays (at the dose rate of 0.75 Gy/min). At each harvest time-point, BM cells were collected from five mice per dose of radiation. We used two methods for detecting NF-κB activation (1) the NF-κB/p65 transcription factor enzyme-linked immunosorbance assay (ELISA) and (2) immunofluorescence staining with NF-κB/p65 antibody. Results from ELISA indicated 2.0 and 2.8-fold increases in NF-κB activation in BM cells isolated at 1 h post-exposure of mice to 0.1 or 1.0 Gy. The immunofluorescence staining method showed similar results. In samples isolated 4 h post-irradiation, however, no activated NF-κB signal was found, regardless of the method of detection. The data also demonstrated that NF-κB was not activated in bone marrow cells collected either at 1 or 4 h from BALB/cJ mice exposed to a single dose of 0.05 Gy ¹³⁷Cs γ-rays. Taken together, the results from our in vivo study indicate the involvement of NF-κB activation in early response to 0.1 and 1.0 Gy (but not 0.05 Gy) of ¹³⁷Cs γ-rays.