Effects of red ginseng on the regulation of cyclooxygenase-2 of spleen cells in whole-body gamma irradiated mice

Exposure to gamma radiation causes a wide range of biological damage and alterations, including oxidative stress, inflammation and cancer. This study aimed to identify the radioprotective effect of Korean red ginseng extract (RG) against whole-body gamma-irradiation (γIR) in mice and the regulatory mechanisms of the radiosensitive gene in spleen, cyclooxygenase-2 (COX-2). RG was administered intraperitoneally (i.p.) or orally (p.o.) to C57BL/6 mice for five days, which were then exposed to 6.5 Gy of 137Cs-γIR. Thymus and spleen were harvested after three days, and organ size and COX-2 expression of the spleen using Western blotting, were examined. γIR shrank both organs and RG recovered the size of thymus but not spleen. RG also significantly inhibited the increased expression of COX-2 induced by γIR. These results were similar following both routes of RG administration, however i.p. RG administration was more effective, thus it was used in progressive studies. In terms of COX-2 expression related intracellular factors, we found here that γIR activated the p38 MAPK, PI3K/Akt and HO-1 but not NF-κB or Nrf2. Activated p38 MAPK, PI3K/Akt and HO-1 were down-regulated by RG while the RG-induced COX-2 expression was only related to HO-1 activation. These results suggest that RG supplementation provides protective effects against radiation-induced inflammation and cancer, and its potential to be utilized in clinical trials and functional foods.