The small molecule pifithrin-μ reversibility inhibits the mitochondrial pathway of apoptosis. The neuronal effects of pifithrin-μ applied after cardiac arrest are unknown. We hypothesized that pifithrin-μ reduces neuronal damage in the most vulnerable brain region, the hippocampus, after cardiac arrest.
METHODS
In two randomized controlled series we administered pifithrin-μ or control in 109 rats resuscitated after 8 or 10 minutes of cardiac arrest. Neuronal damage was blindly assessed with histology (Fluoro Jade B: FJB, cresyl violet: CV) in the most vulnerable brain region (CA1 segment of hippocampus) and with a series of neurobehavioral tests (Open Field Task, Tape-Removal Test, Morris Water Maze test). Mixed ANOVA was used to combine both series, simple comparisons were done with t-tests or Mann-Whitney U test.
RESULTS
Pifithrin-μ reduced the number of degenerating, FJB-positive neurons by 25% (mixed ANOVA p group = 0.014). This was more prominent after 8 minutes cardiac arrest (8 minutes arrest pifithrin-μ 94 ± 47 vs control 128 ± 37; n = 11 each; 10 minutes arrest pifithrin-μ 78 ± 44, n = 15 vs control 101 ± 31, n = 18; p group* arrest length interaction = 0.622). The reduction of ischemic CV-positive neurons in pifithrin-μ animals was not significant (ANOVA p group = 0.063). No significant group differences were found in neurobehavioral testing.
CONCLUSION
Temporarily inhibition of apoptosis with pifithrin-μ after cardiac arrest decreases the number of injured neurons in the CA1 segment of hippocampus in a cardiac arrest rat model, without clinical correlate. Further studies should elucidate the role of this neuroprotective agent in different settings and with longer cardiac arrest.
