Inhibition of NOX4 reduces the memory impairment in the 6-OHDA-induced PD mouse. (a) Total apomorphine (APO)-induced rotation numbers; (b) retention times in rotarod tests were measured at 4 weeks after 6-OHDA injection in Scb shRNA/AAV2 or NOX4 shRNA/AAV2-injected mice. n = 12. * p < 0.05, ** p < 0.01 vs. sham control. (c–f) Spatial memory evaluation using the time latency (c), swimming speed (d), percentage of time in target quadrant (e), and (f) number of passes through the platform. (g) The novel object recognition test was performed, exploratory time spent for novel objects was recorded, and the discrimination ratio was calculated. n = 12 per group, * p < 0.05, ** p < 0.01, *** p < 0.001 vs. Scb shRNA sham control; # p< 005, ## p< 0.01, ### p< 0.001 vs. Scb shRNA 6-OHDA.