Trelagliptin Ameliorates Memory Decline in Diabetic Rats through the AMPK/AKT/GSK-3β Pathway in the Cerebral Cortex

Examining how hypoglycemic medications affect brain function is one of the best approaches to addressing cognitive impairment. In this study, trelagliptin, a dipeptidyl peptidase-4 (DPP4) inhibitor, was utilized to assess memory loss in diabetic rats through fear conditioning tests. Trelagliptin restored fear memory in diabetic rats that had been disrupted over a relatively long period (24 h) or extended period (5 days). Moreover, trelagliptin treatment reduced the higher incidence of neuronal cell death in the cerebral cortex, as observed via Nissl or hematoxylin and eosin staining. Subsequent analyses revealed that diabetic rats exhibited elevated levels of inflammatory cytokines (p-IKKα and p-NFκB) and a trend toward oxidative damage, indicated by malondialdehyde (MDA), superoxide dismutase 2 (SOD2), and glutathione peroxidase 4 (GPX4) detection. However, administration of trelagliptin reversed these markers to baseline levels. Additionally, trelagliptin activated p-AMPK, p-AKT, and p-GSK-3β. Notably, trelagliptin upregulated the expression of postsynaptic density protein 95 (PSD95) and synaptotagmin 1 (SYT1) while downregulating amyloid precursor protein (APP) and beta-site amyloid precursor protein cleaving enzyme 1 (BACE1). These findings suggest that trelagliptin alleviates cognitive impairment in diabetic rats, likely through AMPK-AKT-GSK-3β-mediated mitigation of oxidative stress, enhancement of synaptic plasticity, and reduction of Aβ accumulation.