Cognitive impairments in type 1 diabetes mellitus model mice are associated with synaptic protein disorders.

An association between type 1 diabetes mellitus (T1DM) and cognitive impairment was recently reported. However, the mechanisms by which T1DM induces cognitive impairment are still unknown. Here, we confirmed that T1DM mice induced by streptozotocin (STZ) injection had impaired working memory and spatial memory. We observed long-term potentiation (LTP) induction defects and synaptic loss in mice 20 weeks after STZ injection. We also found decreased levels of synaptic proteins, including the N-methyl-D-aspartic acid receptor (NMDAR) subunit NR2A, synaptophysin (SYP), and postsynaptic density 95 (PSD95), in the hippocampus and prefrontal cortex, revealing similarities in the alteration patterns of these synaptic proteins in aged Alzheimer's disease (AD) APP/PS1 mice and T1DM mice. Taken together, these findings expand our understanding of the mechanisms underlying T1DM-induced cognitive impairment.