Abstract: OBJECTIVE: To investigate effects of liraglutide on cognitive function and phosphorylation of Tau protein in a streptozotocin (STZ)-induced Alzheimer's disease (AD) in rats. METHODS: 24 male Wistar rats were randomly divided into blank control,sham operation,model and treatment groups,with 6 rats per group. For an AD rat model,each rat received a single injection of STZ (3 mg/kg) into the right intracerebroventricular region. After 14 days,rats in the treated group received subcutaneous injections of liraglutide for 4 weeks. Cognitive functions were detected using the Morris water maze test. Expressions of phosphorylation of Tau protein Ser396 were detected using immunohistochemistry (IHC) and Western blot methods. RESULTS: Results from the Morris water maze test show that both the escape latency and the number of times of crossing the platform for rats from the sham operation group were not significantly different from the blank control group (P>0.05). From the same test,results from the model rats were markedly increased over the sham operation group (P<0.05), that from the treated group were markedly decreased compared to the model group (P<0.05). Results from the IHC and Western blot analyses show that phosphorylations of the Tau protein Ser396 were increased significantly in the model rats (P<0.05) but decreased after liraglutide treatments (P<0.05). CONCLUSION: Our data show that liraglutide improved the STZ-induced damage of spatial learning and memory abilities and reduced expression of phosphorylation of Tau protein Ser396 in the hippocampi of rats.

Key words: liraglutide, streptozotocin, Alzheimer's disease, Tau protein phosphorylation