Therapeutic effect of long-term melatonin treatment on the course and fatal outcome of modeled acute radiation sickness. 
We studied the effect of long-term administration of melatonin to male C57Bl/6 mice starting from day 3 after whole-body γ-irradiation (9.5-10.0 Gy, 7.7-17.1 cGy/min).  It was found that replacement of drinking water with melatonin solution (5 mg/liter) did not reduce the amount of fluid intake throughout the period of acute radiation injury.  The daily dose of melatonin was 0.9-1.2 mg/kg body weight (this parameter was lower at the peak of the disease and increased during the recovery stage).  Melatonin by more than 20% (p<0.05) improved survival of mice exposed to γ-irradiation in a dose of LD97/30, reduced leukopenia during the stage of acute manifestations of the disease and maximum mortality, and increased blood leukocyte count by 40% (p<0.05) by day 12 after irradiation.