Conclusions
These results provide initial evidence to suggest that transfusion of old RBC induces neuroinflammation and impairment of learning and memory. These effects may be mediated by cell-free hemoglobin.
Results
Rats were subjected to Barnes maze and fear conditioning tests from 1 week after blood transfusion. Rats transfused with old RBC but not fresh RBC took a longer time to identify the target hole in the Barnes maze and had less context-related fear conditioning behavior than control rats. Old RBC significantly increased interleukin 6 and ionized calcium-binding adapter molecule 1 in the hippocampus at 24 hours after the transfusion. These effects were attenuated by sulforaphane and minocycline, an antibiotic with anti-inflammatory property. Old RBC solution had a higher concentration of cell-free hemoglobin. Sulforaphane increased haptoglobin, a chelator of cell-free hemoglobin. Rats that received cell-free hemoglobin had a pattern of neuroinflammation and impairment of learning and memory similar to that of rats that received old RBC. Conclusions: These results provide initial evidence to suggest that transfusion of old RBC induces neuroinflammation and impairment of learning and memory. These effects may be mediated by cell-free hemoglobin.