Objective:
We recently reported that post-resuscitation normoxic therapy attenuates oxidative stress in multiple organs and improves post-cardiac arrest (CA) organ injury, oxygen metabolism, and survival. Yet, detailed mechanisms of gene expression patterns and signaling pathways mitigated by normoxic therapy have not been elucidated. Therefore, we assessed post-resuscitation normoxic therapy-modified gene expression of oxidative stress-related signaling molecules.
Methods:
Rats were resuscitated from 10 minutes of asphyxial CA and divided into 2 groups: those that inhaled 100% supplemental O
2
(CA-FIO2 1.0) and those that inhaled 30% supplemental O
2
(CA-FIO2 0.3). Control groups were also prepared for comparison (control-FIO2 1.0, control-FIO2 0.3). At 2 hours after resuscitation, brain and heart tissues were collected, and mRNA purifications followed by real-time PCR measurements were performed to compare gene expression of hyperoxia-induced inflammatory and apoptosis-related signaling pathways amongst these groups.
Results:
In the brain, relative IL-1 beta mRNA gene expression levels, which represent inflammatory signaling pathways, increased post-CA (8.1±2.3 in CA-FIO2 1.0 and 1.0±0.4 in control-FIO2 0.3, p<0.05), but were significantly attenuated by normoxic therapy (2.3±0.2 in CA-FIO2 0.3, p<0.05). Likewise, normoxic therapy significantly reduced oxidative stress-induced inflammatory (NFKB1, TGFB1, MAPK14, TRAF6) and apoptosis-related (BAX, EGF) mRNA gene expression levels in the brain, whereas no statistical differences were detected in the heart.
Conclusions:
Post-CA normoxic therapy significantly attenuated the gene expression of oxidative stress-induced inflammation and apoptosis in the brain, while there were no remarkable changes in the heart. Therefore, it is inferred that the heart is more tolerant to hyperoxic injury compared to the brain.
ATF6 Decreases Myocardial Ischemia/Reperfusion Damage and Links ER Stress and Oxidative Stress Signaling Pathways in the Heart