the effect of erythropoietin on rat’s red blood cell indices in simulated microgravity (experimental study)

purpose: microgravity causes major changes in various systems of the body in space, such as shift in cerebrospinal fluid, decreased red blood cells count, and electrolyte loss. these complications are very important in space and we should find new approaches to prevent the side effects of microgravity in astronauts. materials and methods: this experimental study was conducted on 21 adult male rats in three groups: control, hind-limb unloaded, hind-limb unloaded plus erythropoietin. spss software was used for data analysis. rbc indices were assessed in the first, third and fourteenth day in different groups. results: the highest mean of hemoglobin was 17.98 ± .35 in the hind-limb unloaded plus erythropoietin group (on the 3rd day) and the lowest amount was 13.52 ± 1.22 in the hind-limb unloaded group (on the 14th day). the p value to compare rbc and reticulocyte count in hindlimb unloaded group with those in hind-limb unloaded plus erythropoietin group was .017 (on the3rd day), to compare hemoglobin in hind-limb unloaded group with that in hind-limb unloaded plus erythropoietin group was 0.004 (on the 3rd day), and to compare reticulocyte values in hind-limb unloaded group with those of hind-limb unloaded plus erythropoietin group was 0.036 (on the 14th day). conclusion: the lowest amount of rbc indices was in the hind-limb unloaded group (on the 14th day). rbc indices were significantly higher in hind-limb unloaded plus erythropoietin group than those on the 1st day. erythropoietin injection induced significant improvement in rbc indices in rats under microgravity condition. erythropoietin is very useful to prevent space anemia and its highest effect occurson the 3rd day after injection. this is as an innovative method to prevent space anemia.