ABSTRACT
OBJECTIVE To observe the neurotoxicity of 1-bromopropane(BP) and investigate the protective effects of edaravone(Edv) against BP-induced deficits of spatial learning and memory ability in rats by its anti-inflammatory mechanism. METHODS Adult male Wistar rats were ig given BP 800 mg·kg-1 to develop the model, followed by Edv 1, 3 and 5 mg·kg-1 ip treatment respectively 4 h later for consecutive 12 d. From the 7th day (d 7), all rats were subjected to the five-day place navigation in Morris water maze (MWM) to measure the escape latency and the total swimming distance. On d 6 of MWM, spatial probe test was performed and the crossing times of rats were recorded to evaluate the spatial memory ability. At the end of the behavioral experiment, four rats in each group were randomly selected and the frozen section of the whole brain was sliced for thionin staining and immunohisto?chemistry. The other eight sacrifced rat brains from each group were harvested for the determination of the tumor necrosis factor-α (TNF-α) and nitric oxide (NO) by ELISA and nitrate reductase method, respectively. RESULTS The results of MWM test showed that compared with control rats the escape latencies of rats in BP group were increased by 60.8%, 81.9%,124.0% and 323.3%, respectively, during the d 2-d 5 of MWM, and the total swimming distance increased by 47.0%, 66.4%, 106.0% and 277.6%, respectirely. All the differences between BP group and control group were significant (P<0.05, P<0.01). In the spatial probe trial, the crossing times of rats in BP group were significantly decreased, compared with the control rats (P<0.01). Morphologically, thionin staining and immunohistochemistry revealed significant microglia activation and neuron loss in the rat forebrains, accompanied by a 147.6% and 18.7% increase in NO and TNF-α levels in rats treated with BP respectively compared with control values (P<0.05, P<0.01). After co-treatment at different dosages of Edv with BP, the escape latencies of rats in BP+Edv 5 mg·kg-1 group were decreased by 38.4%and 44.3%(P<0.01), and the total swimming distance decreased 34.5%and 43.3%(P<0.05, P<0.01), respectively, compared with the BP treated rats on the d 4 and d 5 of MWM test. The microglia activation and neuron damage in the brain of rats induced by BP treatment were significantly alleviated in BP+Edv groups. In addition, the contents of NO and TNF-α were decreased in BP+Edv 1, 3 and 5 mg · kg-1 groups, with a decrease of 53.8%, 55.4% and 59.8% in NO, and 12.2%, 15.8% and 22.2% in TNF-α(P<0.05, P<0.01), respectively. CONCLUSION Edv could effectively protect against central neurotoxicity induced by BP via anti-neuro?inflammation.