Background: In our recent studies, yeast double-stranded RNA showed radioprotective effect in mice exposed to 9.4 Gy of gamma radiation. The current work continues our inquiry and describes the changes in the number and morphology of blood cells in mice injected with double-stranded RNA from Saccharomyces cerevisiae prior to gamma irradiation. To be capable of estimating the required parameters, we have used 8 Gy of radiation, which allowed mice to survive for up to 37 days (LD60/30). Materials and Methods: Animals received single intravenous injections of one of the following compounds: (1) 7 mg of total RNA isolated from baking yeast Saccharomyces cerevisiae, (2) 200 μg of double-stranded RNA or (3) 400 μg of double-stranded RNA. 30 minutes later, using a 137Cs gamma emitter, mice were irradiated with a dose of 8 Gy at the rate of 1.4 Gy/min. The radioprotective effect of preparations was assessed based on death rates. Results: Injections of both 200 μg of double-stranded RNA and 7 mg of total RNA prior to irradiation provided the best radioprotective effects, ensuring the survival of 100% of animals. Changes in the number of blood cells and their morphological aberrations were being monitored for 37 days after irradiation. Conclusion: The protection from lethal radiation doses is associated with the preservation and rapid recovery of leukocytic and erythroid lineages.
