缺氧缺血对新生大鼠及小鼠脑细胞线粒体膜电势的影响

Effect of hypoxia-ischemia on the brain mitochondrial membrane potential in neonatal rats and mice

目的了解缺氧缺血(HI)对新生大鼠及新生小鼠脑细胞线粒体膜电势(ΔΨm)的影响。方法7日龄SD大鼠和C57小鼠各160只,分为正常对照组和HIBD后0、1、3、4、8、12h和24h组(各组n=20,其中10只测定海马、大脑皮质、丘脑部位的ΔΨm值),HIBD动物予以右颈总动脉分离结扎再置8%O2低氧舱处理,以流式细胞仪测定ΔΨm,比较同一动物HI损伤侧(右侧,即A侧)与损伤对侧(B侧)之间ΔΨm的比值(即A、BΔΨm比值)变化。结果HI损伤后新生SD大鼠及C57小鼠脑细胞ΔΨm均呈现“降低恢复再降低再恢复再降低”的改变,新生SD大鼠A、B侧ΔΨm比值在HI后0、4、24h出现3次降低,分别为(0.80±0.17)、(0.70±0.22)、(0.71±0.13),新生C57小鼠的该比值在HI后0、24h出现2次降低,分别为(0.84±0.26)、(0.86±0.13);新生SD大鼠改变最明显的部位是大脑皮质区,其HI后0、4、24h的比值为(0.69±0.07)、(0.73±0.11)、(0.65±0.20),新生C57小鼠改变最明显的部位是海马回,其HI后0、4、24h的比值为(0.71±0.16)、(0.71±0.21)、(0.76±0.20);新生SD大鼠和C57小鼠丘脑区的ΔΨm比值变化相对最轻。结论HI导致的脑细胞线粒体功能降低有短时间恢复的可能,两种动物的ΔΨm改变有不同的时间规律和易损部位,提示针对不同部位的HIBD实验研究采用不同方法制备动物模型的可行性。

Objective To study the effect of hypoxia-ischemia （HI） on brain mitochondrial membrane potential （△ψm） in neonatal rats and mice. Methods Newborn SD rats and C57 mice were randomly divided into normal control and post HIBD 0, 1, 2, 3, 4, 8, 12 and 24 h groups （each n = 20, half for regional △ψm assessment of cortex, hippocampus and thalamus ）. HIBD animals were subjected into right carotid artery ligation plus 8% O2 inhalation. Flow cytometry was used to assess the △ψm. The ipsilateral to contralateral △ψm ratio was recorded. Results After HI, the ipsilateral to contralateral △ψm ratio in both newborn SD rats and C57 mice showed ＂ decrease-recovery-decrease-recovery-decrease＂ change pattern. In newborn SD rats, there were three times of decrease at 0, 4 and 24 h after HI, the ratio was （0. 80 ±0. 17）, （0. 70 ± 0. 22） and （0. 71±0. 13）, respectively. In newborn C57 mice, there ere two times of decrease at 0 and 24 h after HI, the ratio was （0. 84±0. 26） and （0. 86±0. 13）. For SD rats, the most vulnerable region was cortex, of which the ratio at 0, 4 and 24 h after HI was （0. 69±0. 07）, （0. 73± 0. 11 ） and （0. 65± 0. 20）. For C57 mice, the most vulnerable region was hippocampus, of which the ratio at 0h,4 and 24 h after HI was （0.71 ± 0.16）, （0.71±0.21） and （0.76± 0. 20）. The least vulnerable region in both SD rats and C57 mice was thalamus. Conclusion There is recovery possibility of HI-induced brain mitochondrial dysfunction within short time after HI. The difference of temporal change and vulnerable region of △ψm between SD rats and C57 mice indicates that different methods of preparing HIBD animal model may suitable for different research purpose.