Figure 4.

Chronic insulin exposure attenuates insulin-induced activation of PI3K and MAPK pathways. rHypoE-19 neurons were pretreated with PBS or 10 nM, 100 nM, or 1000 nM insulin for 24 hours. The cells were then washed with PBS and allowed to recover in fresh medium for 1 hour before being rechallenged with 10 nM insulin or PBS vehicle. Relative phosphorylated AKT (a) or ERK1/2 (b) levels were normalized to total AKT or total ERK levels, respectively. Data are shown with SEMs (n = 3 independent experiments). ***, P < .001, as per 2-way ANOVA with a Bonferroni post hoc test.