The neuroprotective effect of targeted regulation Nrf2 gene on injured brain caused by acute severe carbon monoxide poisoning in rats

Abstract

Objective To explore the neuroprotective effect of targeted regulation Nrf2 gene on rats with brain injury caused by acute severe carbon monoxide (CO) poisoning. Methods A total of 180 healthy adult SD rats were divided into 4 groups at random: normal control group(NC group), CO poisoning group(CO group), lentivirus group(LV group) and Nrf2 gene therapy group(Nrf2 group), and 45 rats in each group. An acute CO toxic rat model was established by inhalation in a hyperbaric oxygen tank. The lentivirus group was directly injected with lentivirus dilution (4×106 TU/μl) into striatum with a microsyringe guided by a stereotactic apparatus, and the Nrf2 gene therapy group was administrated the same dose of recombinant Nrf2 gene lentivirus dilution, while rats in the normal control group and the CO poisoning group were received the same amount of normal saline. Five rats were taken and decapitated at day 1, day 7 and week 2 from each group, respectively. The mitochondrial membrane potential (MMP) of neurons in brain tissue was detected by JC-1 method, and the expressions of Nrf2 and GCLC proteins were observed by immunohistochemistry and Western Blot. Results Compared with the NC group (cortex: (75.3±6.8); hippocampus: (76.4±7.1); striatum: (73.8±7.3)) at the same time point, the MMPs of neurons in CO group (cortex: (34.5±6.7); hippocampus: (30.3±5.6); striatum: (41.5±6.1) and LV group (cortex: (36.8±6.2); hippocampus: (30.8±6.0); striatum: (42.7±6.3)) were significantly decreased, and the difference was significant(P 0.05). A small amount of Nrf2 protein (0.22±0.05) and GCLC protein (0.24±0.04) were expressed in the brain tissue of normal control rats. The expressions of Nrf2 protein (0.31±0.06, 0.31±0.05) and GCLC protein (0.30±0.04, 0.31±0.07) in CO group and LV group were slightly increased (P 0.05). The MMPs value of nerve cells in the Nrf2 group (cortex: (53.3±5.3); hippocampus: (56.9±6.1); striatum: (60.6±6.0)) also decreased, but it was significantly higher than that in the CO group and the LV group at the same time point (P 0.05). Conclusion CO poisoning could induce oxidative stress and damage mitochondrial function of nerve cells. The active state of targeted regulation Nrf2 could significantly enhance the antioxidant capacity of rats and positively protect rats against brain injury induced by acute severe CO poisoning. Key words: Carbon monoxide poisoning; Brain injury; Mitochondrial membrane potential; Nuclear factor E2 related factor 2