Figure 3

Effects of hyperamylinemia on long term memory. The Novel Object Recognition (NOR) protocol was used to assess possible changes in recognition memory in HIP rats. The recognition index (RI) is defined as the ratio of time spent exploring a novel object over the total time spent exploring both familiar and novel objects. A – In comparison with WT rats (N = 10), diabetic HIP (HIP-DM) rats (i.e., non-fasted blood glucose >200 mg/dl; N = 16) showed significant impairment in recognition memory (*P < 0.05). Pre-diabetic HIP rats (HIP-PD; non-fasted blood glucose <200 mg/dl; N = 10) were not different from either WT or HIP-DM rats. B – Total exploration times during the object recognition trial were not significantly different among wildtype (WT), pre-diabetic HIP, and diabetic HIP (HIP-DM) rats. C – A subset of pre-diabetic HIP rats (N = 3) was retested for the novel object recognition approximately 8 weeks after the initial trial, by which time they had developed full-blown T2D (i.e., blood glucose >200 mg/dl). Progressing to full diabetes led to a significant drop in the recognition memory in HIP rats (**P < 0.001) compared to the initial NOR test.