| Objectives:Perinatal hypoxic-ischemic (HI) is one of the most important reasons for brain damage. Hyperbaric oxygen (HBO) is one of the treatments to hypoxic ischemic brain damage (HIBD). The mechanism of HBO remains unclear. Mitochondria are the "energy-producing" organelle of brain cells. The mitochondiral membrane potential (△Ψm) is the indicator of the mitochondrial function. The decrease of△Ψm happens at the early stage after HI insult. In this study, the△Ψm of cells in the cerebral cortex was observed within24hours after HIBD as well as after HBO treatment. The objectives were to observe the influence of HBO to the△Ψm in24hours, and to explore whether HBO may improve the mitochondrial function by influencing△Ψm of the cerebral cortex cells so as to decrease HIBD.Methods:132neonatal SD rats were randomly divided into normal control group, HIBD groups, and HIBD+HBO groups. Rice model of HIBD was used with the left hemisphere to be damaged side (the isplateral side). HBO treatment was started after HI immediately with the end time point of HBO be the0h time point. Rat pups were further divided into0h,2h,4h,6h,12h,24h groups (n=10in one group). Animals were euthanized by decapitation. Single cell suspension of the cortex in left/right hemisphere was prepared respectively, and incubated with Rhodamine123(Rho123), the the markers of△Ψm. The mean fluorescence level (MFL) of Rho123was detected by flow cytometry. The left-to-right (ipsilateral-to-contralateral) ratio of△Ψm was calculated as well.Results:1. For normal control group:The△Ψm of the left hemisphere was (4.72±0.12) MFL, and the left-to-right△Ψm ratio was (1.20±0.05).2. To compare the HIBD groups to normal control group:At Oh,2h,4h,6h,12h,24h after HI, the left cortex△Ψm at each time point was less than normal control group. The△Ψm at each time point was (2.67±0.53),(3.92±2.59),(4.21±0.38),(3.58±0.50),(4.16±0.14), and (3.42±0.34) MFL, respectively. The△Ψm at0h after HI was significantl less than that of normal control group (P<0.05). The left-to-right△Ψm ratio at each time point was (1.12±0.13),(1.06±0.10),(0.89±0.13),(1.13±0.09),(0.95±0.15), and (1.13±0.07), respectively. The ratio was significantly different at4h time point between HIBD and nonnal control groups, between0h and4h after HIBD group, between4h and6h after HIBD group, between4h and24h after HIBD group (P<0.05).3. To compare the HBO+HIBD to normal control groups:At0h,2h,4h,6h,12h, and24h, the left△Ψm of each HBO+HIBD group was (2.58±1.06),(4.03±1.77),(4.53±0.43),(4.68±1.76),(3.85±0.06), and (3.09±0.48) MFL, while the left-to-right ratio was (0.94±0.40),(0.92±0.15),(1.13±0.05),(1.06±0.14),(1.08±0.08), and (1.03±0.16), respectivel. The△Ψm at0h and24h in HBO+HIBD group were significantl less than that in normal group (P<0.05). The left-to-right ratio at0h and2h were significantl less than that in normal group (P <0.05).4. To compare the HIBD+HBO to HIBD groups:The△Ψm of left hemisphere at4h,6h,12h, and24h in HIBD+HBO was significantl higher than that in HIBD group (P<0.05). The left-to-right△Ψm ratio at each time point was not significantly different between HIBD and HBO+HIBD groups (P>0.05).Conclusion:1. HI may cause the decrease of brain cell△Ψm and the left-to-right△Ψm ratio in the cortex in neonatal SD rats.2. Single time HBO treatment right after HI partially reduced the HI-induced the decrease of brain cell△Ψm, but had no influence to the left-to-right△Ψm ratio in the cortex.3. It is uncertain that whether HBO can reduce HIBD via the mechanism of influencing△Ψm during a short period after HI. |
PDF Full Text Request