M Alavi
S Taeb
M A Okhovat
M Atefi
F Negahdari

Background: Hormesis is defined as the bio-positive response of something which is bio-negative in high doses. In the present study, the effect of radiation hormesis was evaluated on the survival rate of immunosuppressed BALB/c mice by Cyclosporine A.Materials and Methods: We used ۷۵ consanguine, male, BALB/c mice in this experiment. The first group received Technetium-۹۹m (۳۷۰۰Bq) and the second group was placed on a sample radioactive soil of Ramsar region (۸۰۰Bq) for ۲۰ days. The third group was exposed to X-rays (۳۶۰۰Bq) and the fourth group was placed on the radioactive soil and then injected Technetium-۹۹m. The last group was the sham irradiated control group. Finally, ۳۰mg Cyclosporine A as the immunosuppressive agent was orally administered to all mice ۴۸ hours after receiving X-rays and Technetium-۹۹m. The mean survival rate of mice in each group was estimated during time. Results: A log rank test was run to determine if there were differences in the survival distribution for different groups and related treatments. According to the results, the survival rate of all pre-irradiated groups was more than the sham irradiated control group (p < .۰۵).  The highest survival time was related to the mice which were placed on the radioactive soil of Ramsar region for ۲۰ days and then injected Technetium-۹۹m. Conclusions: This study confirmed the presence of hormetic models and the enhancement of survival rate in immunosuppressed BALB/c mice as a consequence of low-dose irradiation. It is also revealed the positive synergetic radioadaptive response on survival rate of immunosuppressed animals.

Radiation Hormesis, Survival Rate, BALB/c Mice, Cyclosporine A, Radioadaptive Response