Figure 2.

Brain influx of ¹²⁵I-Aβ40 increased and ¹²⁵I-Aβ42 decreased in insulin-treated B6SJLF1 mice. Normal saline or insulin (INS) was infused into the left internal carotid artery such that the left brain hemisphere received approximately two-fold greater insulin exposure than the right hemisphere. Then ¹²⁵I-Aβ was administered via femoral vein, which is equally distributed to both left and right brain hemispheres. This experimental modality allows us to relate the extent of insulin exposure to changes in the influx of ¹²⁵I-Aβ. (a) The brain influx values of ¹²⁵I-Aβ in mice infused with 1 IU of insulin over 15 min. Data are presented as mean ± S.D. (n = 3); *p < 0.05, Student’s t-test. (b) The brain influx of ¹²⁵I-Aβ into various brain regions of mice infused with 4.2 IU of insulin over 15 min. Data are presented as mean ± S.D. (Aβ40: saline (n = 5), insulin (n = 6); Aβ42: saline (n = 6), insulin (n = 5)). Two-way ANOVA followed by Bonferroni’s multiple comparison test was conducted to evaluate if the differences between saline and insulin-treated mice are significant in various brain regions. *p < 0.05, **p < 0.01, and ***p < 0.001.