Effect of Biantie pretreatment on serum level of PHD2/HIF-1α and brain tissue damage in rats during acute hypobaric hypoxia exposure

Abstract

To observe the effect of Biantie (bian stone plaste) pretreatment on serum level of prolyl hydroxylase domain 2 (PHD2) and hypoxia-inducible factor-1α (HIF-1α) in rats with acute hypobaric hypoxia induced-brain injury, and to explore the possible mechanism of Biantie on preventing brain injury at high altitude. Forty-five male SD rats were randomly divided into a blank group, a model group, a Biantie group, a medication group and a Biantie+inhibitor group, 9 rats in each group. The rats in the Biantie group the and the Biantie+inhibitor group were pretreated with Biantie at "Taiyuan" (LU 9), "Neiguan" (PC 6) and "Renying" (ST 9), 2 h each time, once a day; the rats in the medication group were treated with intragastric administration of rhodiola capsule solution (280 mg/kg) for 14 d; the rats in the Biantie+inhibitor group were intraperitoneally injected with the PHD inhibitor dimethyloxalyl glycine (DMOG) at a dose of 40 mg/kg 24 h before the establishment of the model. After the intervention, except for the blank group, the rats in the remaining 4 groups were placed in the oxygen chamber to simulate a high-altitude environment to establish the acute hypobaric hypoxia brain injury model. The arterial blood-gas analysis indexes [blood oxygen saturation (SaO2), lactic acid (Lac), blood sodium (Na+), blood potassium (K+)] and brain water content were detected in each group; the histomorphology of cerebral cortex was observed by HE staining; the serum levels of PHD2 and HIF-1α as well as vascular endothelial growth factor (VEGF) were detected by ELISA; the VEGF protein expression in brain tissue was detected by Western blot; the VEGF mRNA expression in brain tissue was detected by real-time fluorescent quantitative PCR. Compared with the blank group, the levels of SaO2 and Na+ in the model group were decreased (P<0.05), while the levels of Lac and K+ as well as the water content of brain tissue were increased (P<0.05). Compared with the model group, the level of SaO2 in the Biantie group and the medication group was increased (P<0.05), while the levels of Lac, K+ and the water content of brain tissue were decreased (P<0.05); the level of Na+ in the Biantie group was increased (P<0.05). Compared with the Biantie group, the level of SaO2 in the Biantie+inhibitor group was decreased (P<0.05), and the level of Lac and the water content of brain tissue were increased (P<0.05). In the model group, the cortical tissue cells were loose and disordered, the cortical blood vessels were dilated, and the cells were obviously swollen; the anoxic injury in the Biantie group and the medication group was lighter, and the anoxic injury in the Biantie+inhibitor group was more obvious than that in the Biantie group. Compared with the blank group, the serum PHD2 content in the model group was decreased and the HIF-1α content was increased (P<0.05), and the content of VEGF in serum and VEGF protein and mRNA expressions in brain were increased (P<0.05). Compared with the model group, the content of PHD2 in serum in the Biantie group and the medication group was increased (P<0.05), and the level of HIF-1α was decreased (P<0.05), and the content of VEGF in serum as well as VEGF protein and mRNA expressions in brain were decreased (P<0.05). Compared with the Biantie group, the serum PHD2 content in the Biantie+inhibitor group was decreased and HIF-1α level were increased (P<0.05), and the content of VEGF in serum as well as VEGF mRNA expression in brain were increased (P<0.05). Biantie at "Taiyuan" (LU 9), "Neiguan" (PC 6) and "Renying" (ST 9) could regulate serum PHD2/HIF-1α to down-regulate VEGF expression, reduce brain edema and enhance anti-hypoxia ability, so as to achieve the purpose of preventing brain injury at high altitude.