主催: The Japan Radiation Research Society
共催: Asian Association for Radiation Research
We previously reported that the apoptosis index in jejunal crypt cells was significantly greater in spontaneously hypertensive rats than in Wistar-Kyoto rats after X irradiation and that administration of reserpine to induce sympathetic dysfunction of spontaneously hypertensive rats or Wistar-Kyoto rats resulted in a significant suppression of apoptosis. We hypothesized that hyperfunction of the sympathetic nervous system is involved producing the high susceptibility to radiation-induced apoptosis of the jejunal crypt cells. To clarify this hypothesis, we examined the effect of norepinephrine (NE) on cell survival using the clonogenic assay and apoptosis after X-ray irradiation in rat ileal epithelial cells (IEC-18).
NE treatment in rat ileal epithelial cells resulted in the decrease of cell survival in a dose dependent manner (>1µM). A combination of NE 1µM and radiation decreased surviving fraction at 8 Gy from 24.1% to 6.4 % significantly. NE concentration 1µM resulted in increase the apoptotic rate from 3.5 % to 6.0 % 6 h after 8 Gy irradiation (p<0.05). The NE induced cell sensitivity to radiation was attenuated by alpha1-adrenergic antagonist (prazosin) but was not affected by beta-adrenergic antagonist (propranolol).
Our study suggested that NE enhanced sensitivity to radiation in rat epithelial cells and that may be caused through alpha adrenergic receptor.