Inhibition of calpains improves memory and synaptic transmission in a mouse model of Alzheimer disease
J. Clin. Invest. Fabrizio Trinchese, et al. 118:2796 doi:10.1172/JCI34254 [Go to this article.]

Figure 1
The calpain inhibitor E64 reestablished normal synaptic function in APP/PS1 mouse hippocampal cultures. (A) Calpain 1 immunoreactivity colocalized with immunofluorescence for the presynaptic protein, synapsin I. Calpain 1–immunoreactive puncta (left panel). Synapsin I–immunoreactive puncta (middle panel). Colocalization of calpain-immunoreactive puncta with synapsin I–immunoreactive puncta (so that the puncta appear yellow) (right panel). Scale bar: 15 μm. (B) Western blot demonstrated that E64 annulled calpain cleavage of spectrin to its 150-kDa fragment (n = 5 per group). (C) Quantitative western blot analysis of the 150-kDa fragment showed a 32% increase in APP/PS1 cultures compared with WT cultures (n = 5 for both; P < 0.05; data normalized against α-tubulin). (D) Vehicle-treated (veh-treated) APP/PS1 cultures showed approximately 2-fold increase of spontaneous mEPSC frequency (n = 10) compared with vehicle-treated WT cultures (n = 10; P < 0.01, with 1-way ANOVA). E64 did not affect average basal mEPSC frequency in WT cultures (n = 10; P > 0.05 with t test) but reestablished normal basal frequency of spontaneous neurotransmitter release in APP/PS1 cultures (n = 6). (E) Application of glutamate no longer enhanced mEPSC frequency in cultures from vehicle-treated APP/PS1 mice compared with cultures from vehicle-treated WT mice (n = 10 in APP/PS1 cultures; n = 10 in WT littermate cultures; P < 0.01 with 2-way ANOVA) without affecting mEPSC amplitude in either genotype (data not shown). Block of calpain activity through E64 ameliorated the deficit in long-lasting enhancement of synaptic transmission (n = 10; P < 0.01 compared with vehicle-treated APP/PS1 cultures), without affecting it in WT cultures (n = 10; P > 0.05 compared with vehicle-treated WT cultures).