关键词: 脑缺血, Ngn2基因, 核因子E2相关因子2, 血红素氧化酶1, Nrf2/HO-1, 脑微结构, 角质细胞活性

Abstract: BACKGROUND: Heme oxidase-1 (HO-1) plays an important role in cerebral ischemia-reperfusion injury. Nuclear factor-erythroid 2-related factor 2 (Nrf2) can reduce cerebral ischemia-reperfusion injury via regulating downstream antioxidant proteins. Therefore, it is speculated that Nrf2/HO-1 has a certain regulatory role in brain diseases.
OBJECTIVE: To explore the effects of Neurogenin 2 (Ngn2) on brain microstructure and keratinocyte activity in cerebral ischemia rats by regulating Nrf2/HO-1.
METHODS: Fifty-five SPF male Sprague-Dawley rats were selected, 10 of which were randomly selected as healthy group and the remaining rats were used to establish animal models of cerebral ischemia. After modeling, 40 model rats were randomly divided into 4 groups: rats in model group were intracerebrally injected with normal saline; rats in Ngn2 group were intracerebrally injected with Ngn2 10 mg/kg; rats in Nrf2/HO-1 group was intracerebrally injected with Ho-1 and Nrf2 agonist sulforaphane 10 mg/kg; and rats in combined group received intracerebral injection of Ngn2 combined with Nrf2/HO-1 10 mg/kg. Administration in each group lasted for 3 consecutive days. Fractional anisotropy imaging was used to observe the brain microstructure. Hematoxylin-eosin staining was used to observe the pathological morphology of brain tissue. TUNEL method was used to detect glial cell apoptosis. Western blot and PCR were used to detect Nrf2 and HO-1 protein and mRNA expressions, respectively.
RESULTS AND CONCLUSION: (1) Compared with the healthy group, the relative fraction anisotropy values of the peri-infarct cortex and infarct core were lower in the model group (P < 0.05). Compared with the model group, the relative fraction anisotropy values of peri-infarct cortex and infarct core were increased in the Ngn2 group and Nrf2/HO-1 group (P < 0.05). Compared with the Ngn2 group and Nrf2/HO-1 group, the relative fraction anisotropy values of peri-infarct cortex and infarct core were increased in the combined group (P < 0.05). (2) In the model group, a large number of neurons were damaged, and the cells were sparse, disordered and infiltrated. In the Ngn2 group and Nrf2/HO-1 group, the neurons on the injured side were improved, and the loss, disorder, and adhesion of nerve cells were still observed. In the combined group, the necrosis of nerve cells was reduced and cell infiltration was improved. (3) Compared with the healthy group, the apoptosis of glial cells was higher in the model group (P < 0.05). Compared with the model group, the apoptosis of glial cells was decreased in the Ngn2 group and Nrf2/HO-1 group (P < 0.05). Compared with the Ngn2 group and Nrf2/HO-1 group, the apoptosis of glial cells was decreased in the combined group (P < 0.05). (4) Compared with the healthy group, the expressions of Ngn2 mRNA and Nrf2 and HO-1 at protein and mRNA levels were lower in the model group (P < 0.05). Compared with the model group, the expressions of Ngn2 mRNA and Nrf2 and HO-1 at protein and mRNA levels were increased in the Ngn2 group and Nrf2/HO-1 group (P < 0.05). Compared with the Ngn2 group and Nrf2/HO-1 group, the expressions of Ngn2 mRNA and Nrf2 and HO-1 at protein and mRNA levels were increased in the combined group (P < 0.05). (5) To conclude, Ngn2 can protect rats from cerebral ischemia by regulating Nrf2/HO-1, and the mechanism may be related to improving brain microstructure, keratinocyte activity and expression of Nrf2 and HO-1.

Key words: cerebral ischemia, Ngn2 gene, nuclear factor-erythroid 2-related factor 2, heme oxidase-1, Nrf2/HO-1, brain microstructure, keratinocyte activity