تأثیر شش هفته تمرین شنا بر میزان پروتئین‌‌های AMPK و Sirt1 و عملکرد حرکتی رت‌‌های مدل مالتیپل اسکلروزیس القاء شده با کوپریزون

Extended Abstract 
Background and Aims: Multiple Sclerosis (MS) is one of the most common chronic inflammatory diseases of the central nervous system, impairing both sensory and motor function. The exact etiology of MS remains unclear; however, it is estimated that over 2.8 million people worldwide are affected by the disease. Iran is among the top 10 countries in the world for MS prevalence. Probably, several different factors, including stress, heredity, immune deficiency, autoimmune processes, and environmental factors, especially viral infections, are thought to contribute to its onset and progression. Current anti-inflammatory therapies  that modulate the immune system have limited effects on nerve destruction and clinical disability in the progressive phase of this disease. Similarly, no available treatment has proven effective in preventing cognitive decline through the inhibition of neural degeneration and brain atrophy. Given that exercise may confer anti-inflammatory and neuroprotective effects, the present study aims to evaluate the impact of six weeks of swimming training on AMP-activated protein kinase (AMPK) and Sirtuin 1 (Sirt1) levels, as well as on motor function, in a rat model of MS.
Materials and Methods: In this experimental study, 36 adult rats, with an average age of 12 weeks and weighing 230±14 grams, were obtained from the animal housing center of the faculty of veterinary medicine at Shahid Chamran university of Ahvaz. The rats were randomly assigned to four groups: healthy control, healthy exercise, MS control, and MS exercise in clear polycarbonate cages. During the acclimatization period, the rats’ exercisability was also assessed, and it was determined that all rats were capable of performing voluntary swimming activity. To induce MS, Cuprizone was incorporated into powdered rodent chow at a weight ratio of 0.5% (0.5 g of Cuprizone per 100 g of food). The mixture was thoroughly blended, moistened with water to form pellets, and provided to the animals for six weeks. After this initial period, MS induction was confirmed using the Rotarod test. Cuprizone-containing pellets continued to be administered until week 12, coinciding with the end of the exercise protocol. The voluntary swimming exercise protocol was carried out for six weeks. The duration increased from 10 minutes in the first week to 30 minutes in the sixth week. Time was used as the overload factor during the training weeks. Upon completion of the protocol, motor activity, coordination, and balance were assessed using the open field and Rotarod tests. All behavioral assessments were conducted during the animals’ active light phase, between 9:00 AM and 12:00 PM. Following behavioral testing, hippocampal tissue was extracted for biochemical analysis. Protein levels of AMPK and Sirt1 were quantified using Western blot.
Data were analyzed using one-way ANOVA followed by Tukey’s post-hoc test, with significance set at p<0.05.
Findings: The open-field test results indicated that movement speed and total distance traveled were significantly lower in the MS control group compared with the healthy control group (p=0.001). In contrast, these variables were significantly higher in the MS exercise compared with the MS control group (p=0.001). Similarly, the Rotarod test results showed that the duration of balance on the rod was significantly lower in the MS control compared to the healthy control group (p=0.001). Conversely, the duration on the rod was significantly greater in the MS exercise than in the MS control group (p=0.001). The one-way ANOVA results for hippocampal AMPK and Sirt1 protein levels (Fig 1) revealed significant differences among the experimental groups (p=0.001). Tukey's post hoc analysis for AMPK levels showed that its value in the patient group showed a significant decrease compared to the control group (p=0.001), and after swimming activity, there was a significant increase in the patient's training group (p=0.001), except for the comparison between the healthy control and MS exercise groups (p=0.12). For Sirt1, Tukey’s post-hoc analysis demonstrated significant differences among all groups (p<0.05). Specifically, Sirt1 levels were significantly lower in the MS control compared with the healthy control group (p=0.001) and were significantly higher in the MS exercise compared with the MS control group (p=0.01).
Conclusion: The Cuprizone model, primarily through neuronal cell death, especially in the hippocampus, leads to impairments in movement and balance, as evidenced by deficits in behavioral tests such as the Rotarod and open-field assessments. Previous evidence indicates that exercise may stimulate mitochondrial biogenesis via activation of AMPK and Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), thereby reducing oxidative stress. Exercise has also been shown to increase brain-derived neurotrophic factor (BDNF) levels, a neurotrophin essential for myelin sheath regeneration and neuronal protection. Numerous studies have confirmed that BDNF expression in the hippocampus and other brain regions increases in response to exercise.
The present findings demonstrate that swimming exercise significantly increases AMPK and Sirt1 protein levels in the hippocampal tissue of MS-modeled rats and improves motor function in these animals. These results suggest that swimming may exert neuroprotective and functional benefits in MS, potentially through mitochondrial and neurotrophic pathways. However, further studies with broader experimental designs are warranted to explore the underlying mechanisms and assess the translational potential of these findings in human populations.
Ethical Considerations: All stages of the present research were approved by the Ethics Committee of Shahid Chamran University of Ahvaz and registered with the code (IR.SCU.REC.1402.067).
Funding: This study is the result of a master’s thesis from the Department of Exercise Physiology at Shahid Chamran University of Ahvaz, which was carried out using research grant number SCU.SS1402.266.
Conflict of Interest: The authors declare that there are no conflicts of interest regarding this article.