Sport Physiology

Sport Physiology

The Effect of Moderate-Intensity Continuous Exercise on the miR-155/BDNF/Trkb Signaling Pathway in Temporal Lobe Epilepsy Model Mice

Document Type : Research Paper

Authors
Hanieh Yousefzadeh 1
Mohammad Raza Kordi 2
Siroos Choobineh 2
1 Department of Exercise Physiology, Faculty of Sport Sciences and health, University of Tehran, Tehran, Iran.
2 Professor, Department of Exercise Physiology, Faculty of Sport Sciences and Health, University of Tehran, Tehran, Iran.
10.22089/spj.2026.18520.2403
Abstract
Extended Abstract
Background and Purpose
Epilepsy, a prevalent neurological disorder, is marked by recurrent unprovoked seizures and often accompanied by cognitive impairments in chronic cases. These deficits arise from disrupted neuronal plasticity, inflammation, and dysregulated signaling pathways in brain regions like the hippocampus. Emerging evidence from human and animal studies highlights the neuroprotective role of aerobic exercise, which promotes structural and functional brain adaptations, reduces seizure frequency, and ameliorates cognitive decline. Notably, exercise modulates neurotrophic factors such as brain-derived neurotrophic factor (BDNF) and its receptor, tropomyosin-related kinase B (TrkB), while influencing microRNAs (miRNAs) involved in epileptogenesis. However, the specific impact of aerobic training on the miR-155/BDNF/TrkB signaling axis a pathway implicated in neuroinflammation, neuronal survival, and synaptic plasticity remains unexplored in epilepsy models. The purpose of this study was to investigate the effects of 8 weeks of moderate-intensity continuous training (MICT) on miR-155 expression, BDNF/TrkB activation, and related molecular outcomes in the hippocampus of kainic acid-induced temporal lobe epilepsy rats, aiming to elucidate potential non-pharmacological therapeutic mechanisms for epilepsy management.

Materials and Methods
Twenty male Wistar rats (226.6 g, 6-8 weeks old) were housed under standard conditions (12-h light/dark cycle, ad libitum food/water, 22-25°C, 40-50% humidity) with ethical approval from the University of Tehran. Rats were randomized into four groups (n=5): non-epileptic sedentary, epileptic sedentary, sham, and epileptic with moderate-intensity continuous training (MICT).A 12-day treadmill familiarization protocol involved: days 1-2, stationary treadmill (10 min); days 3-5, 6 m/min (10 min); days 6-9, 10 m/min (10 min); days 10-12, 10 m/min with mild shock, progressing to 10° incline at 12 m/min. Rats scoring 3-4 on adaptation proceeded.Epilepsy was induced 48 h post-familiarization by stereotaxic kainic acid injection (10-15 mg/kg) into hippocampal CA3 under ketamine/xylazine anesthesia; sham received saline. Seizure severity was scored, with status epilepticus defined as continuous high-severity activity. Rats received 3-5 mL saline post-injection for hydration.Maximal oxygen consumption (VO2max) was measured via incremental treadmill test: 5-min warm-up (12 m/min, 0° incline), then +3 m/min every 3 min until exhaustion, retested biweekly.MICT consisted of 8 weeks of treadmill running (5 days/week, 0° incline): 5-min warm-up (10 m/min), 40 min at 60% VO2max (weeks 1-4: 13 m/min; weeks 5-8: 21 m/min).Hippocampal tissue was analyzed post-intervention. Proteins were extracted, quantified by bicinchoninic acid assay, and assessed for brain-derived neurotrophic factor (BDNF) and tropomyosin-related kinase B (TrkB) via Western blotting (10% SDS-PAGE, PVDF transfer, antibody probing). MicroRNA-155 expression was measured using quantitative real-time polymerase chain reaction, involving RNA extraction, cDNA synthesis, and amplification.Data normality was confirmed, and one-way analysis of variance with post-hoc tests analyzed group differences (p<0.05) using statistical software.

Results
The study investigated the effects of 8 weeks of moderate-intensity continuous training (MICT) on the miR-155/BDNF/TrkB signaling pathway in the hippocampus of kainic acid-induced temporal lobe epilepsy rats. Data normality was confirmed using the Shapiro-Wilk test. One-way analysis of variance (ANOVA) with Tukey's post-hoc tests was used to analyze group differences, with significance set at p<0.05.ANOVA revealed that MICT significantly influenced brain-derived neurotrophic factor (BDNF) protein expression in the hippocampus of epileptic rats (η² = 0.976, sig = 0.0001, F(3,13) = 175.5). The MICT group (EPI+MICT) showed a significant increase in BDNF levels compared to the epileptic sedentary group (ES) (difference 0.1674 units, p=0.0001). Specifically, BDNF levels in hippocampal tissue were significantly lower in ES (difference 0.5118 units, p=0.0001) and EPI+MICT (difference 0.3443 units, p=0.0001) compared to the non-epileptic sedentary group (NES). The sham group exhibited higher BDNF levels than ES (difference 0.6105 units, p=0.0001), and EPI+MICT had higher BDNF than ES (p=0.0001). A significant difference was observed between EPI+MICT and sham (difference 0.4431 units, p=0.002), but not between sham and NES (p=0.066).For tropomyosin-related kinase B (TrkB), ANOVA indicated a significant effect of MICT (η² = 0.937, sig = 0.0001, F(3,15) = 74.15). TrkB levels were lower in ES (difference 0.3707 units, p=0.0001) and EPI+MICT (difference 0.2705 units, p=0.0001) versus NES. Sham showed higher TrkB than ES (difference -0.3815 units, p=0.0001). However, MICT did not significantly increase TrkB compared to ES (difference -0.1003 units, p=0.053).Regarding miR-155 expression, ANOVA showed a significant effect of MICT (η² = 0.723, sig = 0.0001, F(3,16) = 13.95). The ES group had significantly higher miR-155 levels than EPI+MICT (p=0.0001), NES (p=0.0003), and sham (p=0.0002). MICT significantly reduced miR-155 in EPI+MICT compared to ES (p=0.029). No significant differences were found between sham and EPI+MICT (p=0.093), NES and sham (p=0.997), or NES and EPI+MICT (p=0.132).These findings indicate that MICT enhances BDNF expression and reduces miR-155 levels in epileptic rats, potentially mitigating epileptogenesis via modulation of the miR-155/BDNF/TrkB pathway, though TrkB expression remained largely unchanged.

Conclusion
This study demonstrates that 8 weeks of moderate-intensity continuous training (MICT) significantly improves molecular outcomes in a kainic acid-induced temporal lobe epilepsy rat model. MICT markedly increased hippocampal brain-derived neurotrophic factor (BDNF) expression and reduced miR-155 levels, suggesting a protective role against epileptogenesis. These changes likely contribute to enhanced neuronal function and reduced seizure susceptibility, potentially mediated by the inhibition of neuroinflammatory pathways and activation of BDNF/TrkB signaling. Although tropomyosin-related kinase B (TrkB) levels showed no significant increase, the overall molecular improvements highlight MICT's therapeutic potential. Given the poorer physical activity levels observed in epilepsy patients, these findings advocate for incorporating moderate-intensity aerobic exercise as a non-pharmacological strategy to enhance health outcomes. Future research should explore larger human cohorts and additional neurotrophic factors to further validate and expand these findings, supporting the integration of exercise into epilepsy management protocols.

Article Message
This study highlights the therapeutic potential of 8-week moderate-intensity continuous training (MICT) in a rat model of temporal lobe epilepsy. MICT significantly increased hippocampal BDNF expression and reduced miR-155 levels, suggesting a neuroprotective role by modulating the miR-155/BDNF/TrkB pathway. While TrkB levels remained largely unchanged, the enhanced molecular profile indicates reduced seizure susceptibility and improved neuronal function. These findings advocate for aerobic exercise as a non-pharmacological intervention to mitigate epileptogenesis and enhance health outcomes in epilepsy. Clinicians should encourage physical activity in epilepsy management, with future research exploring broader applications in human populations.
 
Ethical Considerations
In this study, for the care and use of laboratory animals, we adhered to the ethical approval granted by the Ethics Committee (for the care and use of animals) at the Faculty of Sport Sciences and Health, University of Tehran (ethical approval code: IR.UT.SPORT.REC.1403.067). In accordance with the animal ethics committee policies, the number of animals used was minimized.  

Authors’ Contributions
Conceptualization: Kordi, M.
Data Collection: Yousefzadeh, H
Data Analysis: Yousefzadeh, H
Manuscript Writing: Yousefzadeh, H
Review and Editing: Kordi, M; Choobineh, S.
Literature Review: Yousefzadeh, H; Kordi, M; Choobineh, S.
Project Manager:
Any Other Contribution:

Conflict of Interest
The authors declare no conflict of interest.

Acknowledgments
We express our gratitude to the officials of the Animal Laboratory at the Faculty of Sport Sciences and Health, University of Tehran, for their collaboration in this research.
 
Keywords
Epilepsy
miR-155/BDNF/TrkB signaling
temporal lobe
Moderate-intensity continuous training
Subjects
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  • Receive Date 21 September 2025
  • Revise Date 10 February 2026
  • Accept Date 15 February 2026