Increases in brain catecholamine levels counteract memory deficits and reduces Aβ deposition in 5XFAD male mice

Alzheimer's disease (AD) is a degenerative brain disease that presents with neurological symptoms and memory loss, with no clear treatment. Catecholamines, including dopamine, epinephrine, and norepinephrine, can inhibit or degrade the abnormal aggregation of proteins that cause diseases; however, developing these catecholamines as medication is difficult. This study aimed to demonstrate that increasing the levels of catecholamines in the brain may help improve symptoms of AD. We tested whether an increase in catecholamines by bupropion, a dopamine and norepinephrine re-uptake inhibitor, improves the symptoms of AD. Dopamine and norepinephrine showed similar effects in inhibiting amyloid β (Aβ) aggregation and the decomposition of Aβ aggregates as curcumin, a positive control. Dopamine and norepinephrine blocked Aβ aggregates-induced abnormal hippocampal long-term potentiation. The intraperitoneal administration of bupropion increased the concentrations of dopamine and norepinephrine in the hippocampus from 1 to 6 h after administration. In the Aβ-induced memory decline model, bupropion showed a dose-dependent improvement in learning and memory. In 5XFAD mice administered bupropion for 2 months, significant improvements in memory and Aβ deposition were also found compared to vehicle-treated 5XFAD mice. These results suggest that the symptoms of AD can be improved or delayed by increasing the amount of dopamine and norepinephrine using bupropion.