Preconditioning by high-intensity interval training and moderate continuous training differentially affect hippocampal neurotrophic and inflammatory gene expression under acute noise stress in rats

Objectives: This study compared high-intensity interval training (HIIT) versus moderate continuous training (MCT) as preconditioning on hippocampal BDNF, TrkB, and TNF-α gene expression in rats exposed to acute noise stress. Methods: Forty-two male Wistar rats were randomised into seven groups (n = 6): control, time-control, stress, HIIT, MCT, HIIT+stress, and MCT+stress. Exercise groups underwent 8-week treadmill training (5 sessions/week). HIIT (6x2-min intervals, 85–90% Vmax) or MCT (22-min continuous, 65–70% Vmax). Stress groups received a single 4-hour noise exposure. Hippocampal mRNA was quantified via real-time PCR. Results: Both HIIT and MCT significantly upregulated BDNF versus time-control, with HIIT eliciting greater increases. MCT significantly elevated TrkB versus time-control. Noise stress reduced BDNF and TrkB while increasing TNF-α. Both exercise protocols attenuated these alterations. Under stress, HIIT+stress exhibited significantly higher TrkB than MCT+stress. MCT elevated TNF-α versus time-control, but stress-induced increases were similarly mitigated in both preconditioned groups. Correlation analysis revealed strong positive correlations between BDNF and TrkB and moderate correlations between BDNF and TNF-α, and TrkB and TNF-α. Conclusion: HIIT and MCT differentially modulate hippocampal gene expression. While MCT effectively upregulates basal TrkB, HIIT provides superior protection against stress-induced TrkB suppression, highlighting intensity-specific neuroprotective adaptations and integrated pathway regulation among BDNF, TrkB, and TNF-α.