Aerobic and resistance training similarly enhance hippocampal BDNF expression in aged rats: implications for exercise‑induced neuroplasticity

The molecular mechanisms underlying exercise-induced neuroplasticity remain incompletely understood, particularly regarding comparative effects of aerobic versus resistance training on hippocampal neurotrophic signaling in aging. Here we investigated the impact of these two exercise modalities on serum and hippocampal brain-derived neurotrophic factor (BDNF) expression in aged rats. Thirty male Wistar rats (23 months old) were randomly assigned to sedentary (SED), aerobic exercise (AEG), or resistance exercise (REG) groups (n = 10 each). AEG performed progressive treadmill running while REG completed weighted swimming (50–70% body weight), 5 days/week for 8 weeks. Both training protocols significantly reduced serum lactate and increased BDNF concentrations in serum and hippocampus relative to SED (p < 0.05), with no differences between AEG and REG. Densitometric analysis confirmed ~ 35–40% greater BDNF immunoreactivity in the dentate gyrus and CA1-CA3 regions of trained animals (p < 0.01). These findings demonstrate equivalent hippocampal neurotrophic adaptations to aerobic and resistance training in the aged brain, suggesting convergent activation of BDNF-mediated plasticity pathways regardless of exercise modality. Our results support the hypothesis that peripheral metabolic signals (e.g., lactate) and myokines converge on hippocampal BDNF/TrkB signaling during aging-targeted exercise interventions.