Effects of sulforaphane on anxiety and fear memory in AD mice and its oxidative stress mechanism / 中华行为医学与脑科学杂志

ABSTRACT

Objective:To explore the effects of sulforaphane (SFN), an activator of Nrf2, on anxiety and fear memory in Alzheimer's disease(AD) model mice and mechanism.Methods:The AD mice and wild type (WT) mice with the same background were randomly divided into four groups ( n=12 for each group): wild type + normal saline group (WT+ NS), wild type + sulforaphane (WT+ SFN), AD model + normal saline group (AD+ NS) and AD model + sulforaphane group (AD+ SFN). SFN was dissolved in normal saline (0.9% NaCl) and prepared solution with concentration of 1 g/L.According to body weight, mice in WT+ SFN group and AD+ SFN group were intraperitoneally injected with SFN (10 mg/kg), and mice in WT+ NS group and AD+ NS group were intraperitoneally injected with the same volume of normal saline once a day for 30 days.The open field test was used to detect the autonomous exploration ability and anxious behavior of mice.The elevated cross maze was used to detect the anxiety of mice.Conditional fear test was used to test the fear memory behavior of mice.Finally, the expression of superoxide dismutase(SOD) and malondialdehyde(MDA) in the hippocampus and cerebral cortex were detected by ELISA.Two-way ANOVA analysis was performed using GraphPad Prism 8.0.2 software. Results:In the open field test, the percentage of time in central region in AD+ SFN group ((9.99+ 0.37)%) was higher than that of AD+ NS group ((8.47+ 0.42)%) ( q=3.842, P<0.05). In the elevated cross maze, the percentage of time in open arm of AD+ SFN group ((26.2±1.6)%) was higher than that in AD+ NS group ((15.8±1.0)%) ( q=7.452, P<0.01). In the conditional fear test, all the mice of the four groups developed the fear memory, but AD+ SFN group showed higher freezing time ratio ((64.5±3.8)%) than AD+ NS group ((51.0±4.3)%)( q=5.266, P<0.01) in the testing stage.After SFN intervention, the important indicator of oxidative stress, the expression levels of SOD in hippocampus ( q=6.370, P<0.01) and cortex ( q=7.858, P<0.01) of AD mice increased, while the level of MDA in hippocampus ( q=5.146, P<0.05) and cortex ( q=5.833, P<0.01) decreased. Conclusion:SFN may inhibit oxidative stress through Nrf2 pathway, thereby improving anxiety and fear memory in AD mice.