Figure 6
Learning and memory impairment in p17-injected mice. Cognition was tested with the novel object recognition test (NOR) and Morris water maze test (MWM). (a–c) In the NOR, p17-injected animals (p17) lost the ability to discriminate a novel object from a familial one. Vehicle = Control animals injected with vehicle. (a) p17 mice explored similarly to Vehicle mice one of two identical “A” objects in “A + A” at time 0 h, despite higher variability in the former mice. (b) p17 mice showed lesser exploration of a novel object “B” than Vehicle mice when exposed to objects “A + B” 2 h later. (c) p17 mice also spent less exploration time in a novel object “C” than Vehicle mice when exposed to objects “B + C” 24 h later. (d–f) In the MWM, p17-injected animals had deficiencies in spatial learning and memory. (d) p17 mice showed lower abilities than Vehicle mice throughout six days of training to find the position of a hidden scape platform by relaying on distinctive landmarks around a circular pool (CL = cue learning at day 0, P = place task learning at days 1–6). (e) p17 mice spent less time swimming in the pool quadrant where the platform had been located than Vehicle mice when the platform was removed for the probe trial of retention. (f) The computer generated tracks showed that p17 mice swam at random, whilst Vehicle mice swam preferentially in the platform quadrant (representative tracks of Vehicle and p17 mice; circle indicates the previous platform position) during the retention trial. Mean ± SE, n = 7 mice/group in (a–c) and n = 8 mice/group in (d,e). Chance performance is 50% in (a-c) and 25% in (e). *P < 0.05 and **P < 0.01 vs. Vehicle, unpaired Student’s t-test in (b,c,e), # P < 0.05 effect of factor treatment in two-way repeated measures ANOVA in (d).
