Introduction: Cardiac fibrosis is one of the major outcomes of metabolic disorders caused by high-fat diets (HFD), and the TGF-β/Smad signaling pathway is considered a key factor in its development. The present study aimed to investigate the effect of eight weeks of high-intensity interval training (HIIT) and semaglutide, separately and in combination, on the expression of TGF-β1 and Smad2/3 proteins in HFD-fed mice.

Methods: In this experimental study, 30 mice were divided into the following groups: normal diet, HFD, HFD + HIIT, HFD + semaglutide, and HFD + HIIT + semaglutide. The training and drug interventions were carried out for eight weeks. At the end of the study, the expression of TGF-β1 and Smad2/3 proteins in cardiac tissue was measured using the Western blot method.

Results: A high-fat diet significantly increased TGF-β1 and Smad2/3 expression (P=0.001). All three interventions (HIIT, semaglutide, and HIIT + semaglutide) significantly reduced TGF-β1 levels compared with the HFD group (P=0.001). Regarding Smad2/3, although the high-fat diet increased its expression, none of the interventions caused a significant change in this marker.

Conclusion: The findings of this study indicate that a high-fat diet exacerbates cardiac fibrosis through activation of the TGF-β/Smad pathway. All interventions, including HIIT, semaglutide, and their combination, were able to inhibit part of this effect at the level of TGF-β1, but no significant changes were observed in Smad2/3. This suggests that short-term modulatory effects are mainly evident at the level of TGF-β1, and further studies are required to clarify the precise role of Smad2/3.