Role of Nrf2/HO-1 signaling pathway in edaravone-induced attenuation of long-term cognitive impairment caused by long-time sedation with propofol in neonatal rats / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the role of nuclear factor E2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling pathway in edaravone-induced attenuation of long-term cognitive impairment caused by long-time sedation with propofol in the neonatal rats.Methods:Eighty SPF healthy newborn Sprague-Dawley rats of both sexes, aged 7 days, weighing 15-20 g, were divided into 4 groups ( n=20 each) using a random number table method: control group (group C), propofol group (group P), edaravone+ propofol group (group EP) and Nrf2 inhibitor ML385+ edaravone+ propofol group (group MEP). Propofol 75 mg/kg was intraperitoneally injected once a day for 7 consecutive days in P group, EP group and MEP group, respectively, while the equal volume of medium/long chain fat emulsion injection was intraperitoneally injected in C group. Edaravone 3 mg/kg was intraperitoneally injected at 30 min before each propofol injection in EP and MEP groups, and ML385 15 mg/kg was intraperitoneally injected simultaneously in group MEP. The spontaneous activity was evaluated by the open field test on day 29 after birth, and the cognitive function was assessed by Morris water maze test on days 30-34 after birth. The rats were sacrificed after the end of water maze test, and brains were removed and hippocampal tissues were obtained for determination of reactive oxygen species (ROS) levels (by flow cytometry), superoxide dismutase (SOD) and malondialdehyde (MDA) levels (by enzyme-linked immunosorbent assay) and expression of Nrf2 and HO-1 (by Western blot) and for microscopic examination of the pathological changes in the hippocampal CA1 area (using HE staining). Results:There was no significant difference in the speed, distance and time of stay at the center of the open field among the four groups ( P>0.05). Compared with C group, the escape latency was significantly prolonged, the number of crossing the original platform quadrant was reduced, the levels of MDA and ROS were increased, the activity of SOD was decreased, the expression of Nrf2 and HO-1 was down-regulated ( P<0.05), and the pathological injury was observed in the hippocampal CA1 region in group P. Compared with P group, the escape latency was significantly shortened, the number of crossing the original platform quadrant was increased, the levels of MDA and ROS in the hippocampus were decreased, the activity of SOD was increased, the expression of Nrf2 and HO-1 was up-regulated ( P<0.05), and the pathological injury in the hippocampal CA1 region was significantly alleviated in EP group. Compared with EP group, the escape latency was significantly prolonged, the number of crossing the original platform quadrant was reduced, the levels of MDA and ROS were increased, the activity of SOD was decreased, the expression of Nrf2 and HO-1 was down-regulated ( P<0.05), and the pathological injury was aggravated in the hippocampal CA1 region in MEP group. Conclusions:The mechanism by which edaravone attenuates long-term cognitive impairment caused by long-time sedation with propofol is related to activation of Nrf2/HO-1 signaling pathway and inhibition of oxidative stress in the neonatal rats.