Fig. 5

APN deficiency attenuated AMPK phosphorylation causing insulin resistance and deregulated insulin signaling in APN-KO mice. Representative image of immunoblotting indicated reduction of pAMPK^T172/AMPK ratio in both the hippocampus and frontal cortex by (a) 9-mth-old and (b) 18-mth-old of APN-KO mice. c Increased level of IRS-1 phosphorylation at Serine ⁶¹⁶ shown by immunoblotting in the frontal cortex of APN-KO mice. Representative immunoblotting analysis and densitometric analysis of the ratio of insulin signaling effectors (pAkt^S473/Akt, pGSK3β^S9/GSK3β, pGSK3β^Y216/GSK3β) in the hippocampus and frontal cortex of APN-KO mice or WT mice by (d) 9-mth-old & (e) 18-mth-old WT and APN-KO mice. f Representative image and densitometric analysis of pAkt level induction in the right hippocampus of WT mice and APN-KO mice in response to stereotaxic insulin injection. Mean ± S.E.M.; *p < 0.05, **p < 0.01, ***p < 0.001, n.s. statistically not significant; WT (n = 3) vs APN-KO (n = 3 or 4)