Elevated plus maze, Barnes maze, and Novel object recognition test in different groups of R6/2 and WT mice.

<p>Entry and time spent in open and closed arms of elevated plus maze (A, B): At week 8 of age, all R6/2 mice showed more percentage of entries (A), and spent more time in the open arm (B) compared with WT. In R6/2 mice having striatal overexpression of pENK, a reduction in percent of entries (A) and percent of time elapsed (B) in the open arms was observed compared with intact age-matched R6/2 mice. The percentage of entries and the proportion of time spent in the closed arms was exactly the reverse of what was seen for the open arms. Data are presented as mean percent of entries or mean percent of time spent in the open or closed arms / time spent in all four arms ± SEM. *** p<0.0005 vs. WT; + p<0.01, ++ p<0.005 vs. R6/2 (Intact). Learning and memory in Barnes maze (C, D) and Novel object recognition test (E): In Barnes maze performance, started at week 7 of age, no difference was observed in latency to find escape hole between different groups during trial days (C). At probe day 5^th (D), R6/2 mice having striatal injection of rAAV2-GFP showed increased latency to find target hole compared to WT and pENK-injected R6/2 mice. Whereas no difference was detected between pENK-injected R6/2 mice and WT, while intact R6/2 mice tended to spent longer time to reach the target hole compared with WT counterparts. At probe day 12^th (D), the time latency to find target hole was higher in all groups of R6/2 than WT. Novel object recognition test, at week 9, showed that in 1 hour retention test (E), intact R6/2 mice spent less time to explore the novel object compared to WT. Less preference toward novel object was even more pronounced in GFP-injected R6/2 mice compared with WT and pENK-injected group. Interestingly, recognition of novel object was considerably improved in R6/2 mice having striatal overexpression of pENK. Data are presented as percent of the time spent exploring the new object/ total time exploring new and familiar objects ± SEM. * p<0.01, ** p<0.005, *** p<0.0005 vs. WT; + p<0.01, ++ p<0.005 vs. R6/2 (Intact); # p<0.01 vs. R6/2 (GFP).