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. Jul-Sep 2019;9(3):122-126.
doi: 10.4103/2045-9912.266986.

Inhalation of High-Concentration Hydrogen Gas Attenuates Cognitive Deficits in a Rat Model of Asphyxia Induced-Cardiac Arrest

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Inhalation of High-Concentration Hydrogen Gas Attenuates Cognitive Deficits in a Rat Model of Asphyxia Induced-Cardiac Arrest

Lei Huang et al. Med Gas Res. .
Free PMC article

Abstract

Cognitive deficits are a devastating neurological outcome seen in survivors of cardiac arrest. We previously reported water electrolysis derived 67% hydrogen gas inhalation has some beneficial effects on short-term outcomes in a rat model of global brain hypoxia-ischemia induced by asphyxia cardiac arrest. In the present study, we further investigated its protective effects in long-term spatial learning memory function using the same animal model. Water electrolysis derived 67% hydrogen gas was either administered 1 hour prior to cardiac arrest for 1 hour and at 1-hour post-resuscitation for 1 hour (pre- & post-treatment) or at 1-hour post-resuscitation for 2 hours (post-treatment). T-maze and Morris water maze were used for hippocampal memory function evaluation at 7 and 14 days post-resuscitation, respectively. Neuronal degeneration within hippocampal Cornu Ammonis 1 (CA1) regions was examined by Fluoro-Jade staining ex vivo. Hippocampal deficits were detected at 7 and 18 days post-resuscitation, with increased neuronal degeneration within hippocampal CA1 regions. Both hydrogen gas treatment regimens significantly improved spatial learning function and attenuated neuronal degeneration within hippocampal CA1 regions at 18 days post-resuscitation. Our findings suggest that water electrolysis derived 67% hydrogen gas may be an effective therapeutic approach for improving cognitive outcomes associated with global brain hypoxia-ischemia following cardiac arrest. The study was approved by the Animal Health and Safety Committees of Loma Linda University, USA (approval number: IACUC #8170006) on March 2, 2017.

Keywords: brain resuscitation; cardiac arrest; cognitive deficit; global brain ischemia; high concentration hydrogen gas; neuron; rat; water maze.

Conflict of interest statement

Conflicts of interest

None declared.

Figures

Figure 1
Figure 1
Effect of hydrogen (H2) treatment on the T-maze test of rats with asphyxia induced-cardiac arrest (ACA) at 7 days post-resusciation. Note: Rats subjected to ACA had significantly lower rates of spontaneous alteration between the right and left arms than shams. There was a tendency toward improved T-maze performance in ACA rats that received hydrogen gas pre&post-treatment. Data were presented as the mean ± SEM (n = 6/group). *P < 0.05, vs. sham group (one-way analysis of variance followed by Student-Newman-Keuls post hoc test).
Figure 2
Figure 2
Effect of hydrogen (H2) treatment on the Morris water maze test of rats with asphyxia induced-cardiac arrest (ACA) starting at 14 days post-resuscitation. Note: (A) Swimming distance. There were signficant longer swimming distances in rats subjected to ACA at the 4th day of spatial learning testing. H2 treatment significantly shortened the total swimming distance. (B) Latency. Probe test showed that rats subjected to ACA spent significantly lesser time than shams in the quadrant where the platform was placed during spatial learning testing. This effect was diminished by H2 treatments. Data were presented as the mean ± SEM (n = 6/group). *P < 0.05, vs. sham group; #P < 0.05, vs. ACA group (one-way analysis of variance followed by Student-Newman-Keuls post hoc test).
Figure 3
Figure 3
Effect of hydrogen (H2) treatment on the neuronal survival in the hippocampal CA1 region of rats with asphyxia induced-cardiac arrest (ACA) at 7 and 14 days (d) post-resusciation. Note: (A) In rats subjected to ACA, there were signifcantly greater number of Fluoro-Jade staining positive neurons, suggesting neuronal degeneration. H2 treatment improved neuron survival, which was significant at 14 d post-resuscitation. (B) Quantitative result of Fluoro-Jade staining positive neurons. Data were presented as the mean ± SEM (n = 6/group). *P < 0.05, vs. sham group; #P < 0.05, vs. ACA group (one-way analysis of variance followed by Student-Newman-Keuls post hoc test).

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