Background and Purpose: Alzheimer’s disease (AD) is associated with extensive cognitive impairment and increased tau protein phosphorylation in the hippocampus, which directly affect memory performance. Given that both aerobic exercise and niacin supplementation have shown potential neuroprotective effects in previous studies, investigating their role in modulating AD-induced damage is of great importance. Therefore, the present study aimed to evaluate the individual and combined effects of moderate-intensity aerobic exercise and niacin supplementation on improving memory and reducing tau phosphorylation in a streptozotocin (STZ)-induced AD rat model, to determine which intervention or combination thereof is more effective in mitigating cognitive deficits associated with this disease.
Materials and Methods: In this experimental study, 30 adult male Wistar rats (250±10 g) were randomly divided into five groups (n=6) after an acclimatization period under controlled environmental conditions: Control, AD, AD + Niacin, AD + Exercise, and AD + Combined. The AD model was induced via intracerebroventricular injection of streptozotocin (STZ) under standard stereotaxic and anesthetic conditions. In the intervention groups, moderate-intensity aerobic training was performed on a motorized treadmill for 4 weeks with a gradual increase in intensity. Niacin supplementation was administered via oral gavage at a dose of 100 mg/kg/day for 30 days. To evaluate cognitive performance, the Novel Object Recognition (NOR) test was used to assess short-term and long-term memory, and the T-maze test was used to measure working memory. Following behavioral testing, the expression levels of amyloid-beta (Aβ) and phosphorylated tau (AT8) proteins in the hippocampal tissue were quantified using Western blotting. Data were analyzed using one-way analysis of variance (ANOVA) followed by Tukey's post hoc test, with the significance level set at P