Fig. 3

Increased susceptibility of the mice to amyloid-β peptide (Aβ)-induced learning and short-term memory impairment by arachidonic acid-enriched (ARA) diet. Mice were given intracerebroventricular injections of 0.9% NaCl or soluble Aβ₄₂ oligomers as described in the Methods section of the main text after 10 weeks of the ARA or oleic acid-enriched (OLE) diet. Y-maze tests were performed 4 days after the injection, and a spontaneous alternation behavior and b number of arm entries were measured during a 5-minute session. The training trials with the Morris water maze were performed from 7 to 11 days after the injection. Escape latency was measured (mean of a group of four trials per day) in the training week (c). Results of the probe trial (14 days after the injection) are shown as percentages of time spent in the platform quadrant (d) and in the opposite quadrant (e). * p < 0.05, ** p < 0.01, *** p < 0.001, comparing the four groups of mice for Y-maze test and probe test; * p < 0.05, comparing OLE NaCl and OLE Aβ₄₂ groups; ^# p < 0.05, ^## p < 0.01, comparing ARA NaCl and ARA Aβ₄₂ groups; ^$ p < 0.05, ^$$ p < 0.01, comparing OLE Aβ₄₂ and ARA Aβ₄₂ groups for training with Morris water maze test. All data are presented as mean ± SEM (n = 9–15)