Exercise training and BDNF injections alter amyloid precursor protein (APP) processing enzymes and improve cognition

Exercise reduces cognitive aging, neurodegeneration, and Alzheimer's disease (AD) risk. Acute exercise reduces the activity of β-site amyloid precursor protein-cleaving enzyme 1 (BACE1), the rate-limiting enzyme in the production of Aβ. However, mechanisms mediating these effects remain largely unknown. Work has implicated brain-derived neurotrophic factor (BDNF) in the processing of amyloid precursor protein (APP). BDNF is an exercise-induced neurotrophin known for its role in synaptic plasticity, neurite growth, and neuronal survival. Previously, our lab has shown using an ex vivo model that treatment of the prefrontal cortex with BDNF reduced BACE1 activity, highlighting a BDNF to BACE1 link. The purpose of this research was to examine whether BDNF treatments resulted in similar biochemical adaptations to APP processing as exercise training. Male C57BL6/J mice were assigned into one of four groups (n = 12/group): 1) control; 2) exercise training (progressive treadmill training 5 days/wk); 3) BDNF (0.5 mg/kg body mass subcutaneous injection 5 days/wk); or 4) endurance training and BDNF, for an 8-wk intervention. Recognition memory was measured with a novel object recognition test. Serum, the prefrontal cortex, and hippocampus were collected. BDNF improved recognition memory to a similar extent as endurance training. BDNF and exercise decreased BACE1 activity and increased ADAM10 activity in the prefrontal cortex, indicating a shift in APP processing. Our novel results indicate that BDNF exerts similar beneficial effects on cognition and APP processing as exercise training. Future evidence-based preventative or therapeutic interventions that increase BDNF and reduce BACE1 will be of value for populations that are at risk of AD.NEW & NOTEWORTHY Our study presents the novel findings that chronic peripheral BDNF injections result in regulation of APP processing enzymes and improved cognition to a similar extent as exercise training. These findings highlight the potential efficacy of using BDNF as a therapeutic intervention in the prevention of neurodegenerative diseases (i.e., Alzheimer's disease). Furthermore, future evidence-based preventative or therapeutic interventions that increase BDNF and reduce BACE1 will be of value for populations that are at risk of AD.