Effect of blood-letting puncture of "Well-points" on hippocampal mitophagy-related protein expression in rats with acute brain injury due to hypobaric hypoxia

Abstract

To study the effect of blood-letting puncture at "Well-points" of the twelve meridians on hippocampal mitophagy of hypobaric hypoxia-induced brain injury (HHIBI) rats, so as to explore its biological mechanisms underlying improvement of high altitude hypoxia-induced brain injury. Male SD rats were randomly divided into normal control group （n=9）， and model and blood-letting groups which were further divided into 6, 12, 24, 48 and 72 h subgroups (n=9 in each subgroup). The HHIBI model was established by putting the rats into a hypobaric hypoxia chamber (equivalent to 5 000 m above sea level).The blood-letting groups were given blood-letting therapy at "Shaoshang"(LU11), "Shangyang"(LI1), "Zhongchong"(PC9), "Guanchong"(SJ1), "Shaochong"(HT9), "Shaoze"(SI9), once a day for 7 days. H.E. staining was used to observe the histopatholo-gical changes of hippocampus tissue. Serum hypoxia inducible factor(HIF)-1α and vascular endothelial growth factor(VEGF) contents were assayed using ELISA, and the expression levels of hippocampal Beclin-1 and LC3-Ⅱ proteins detected using Western blot. Compared with the normal control group, the levels of serum HIF-1α and VEGF at each time point, and the expressions of hippocampal Beclin-1 at 12 and 24 h, LC3-Ⅱat each time point were significantly increased in the model group (P<0.05, P<0.01); while in comparison with the model group, the levels of serum HIF-1α and VEGF contents, and the expressions of Beclin-1 at 12 h, LC3-Ⅱ at 24, 48 and 72 h were further significantly up-regulated in the blood-letting group (P<0.01, P<0.05). H.E. staining revealed that the pyramidal cells in the hippocampal CA1 region had a disordered arrangement, and some of them presented swelling with loose and pale cytoplasm or vacuolation at 6, 12 and 24 h, and showed indistinct nucleolus, irregular shape, pyknosis and deep staining and an obvious edema at 48 and 72 h, which was relatively milder in the blood-letting group. Blood-letting of "Well-points" can up-regulate serum HIF-1α and VEGF contents and hippocampal Beclin-1 and LC3-Ⅱ (mitophagy related proteins) expressions in HHIBI rats, which may contribute to its effect in reducing hypoxic brain injury.