The Effect of Fosinopril on Achilles Tendon Healing in a Rat Model

In addition to their antihypertensive effects, angiotensin converting enzyme (ACE) inhibitors possess endothelial protective properties. It has been shown that ACE inhibitors reduce fibrosis and adhesion during the tendon healing process by suppressing angiotensin II. In this experimental study, we aimed to investigate the effect of fosinopril, a commonly used ACE inhibitor in the treatment of hypertension, on Achilles tendon healing in rats. A total of 80 Sprague–Dawley rats were used and divided into four groups: healthy control group (Group 1), Achilles tendon rupture and repair group (Group 2), Achilles tendon rupture and repair with fosinopril administration (Group 3), and healthy rats treated with fosinopril only (Group 4). At the end of the experiment, rats were sacrificed at the 1st, 2nd, and 4th weeks, and the groups were compared using biochemical and histological methods. For statistical analysis, data distribution was assessed for normality. Group comparisons were conducted using one-way ANOVA or the Kruskal–Wallis test as appropriate, followed by post hoc pairwise comparisons with correction for multiple testing. According to the biochemical analysis, the levels of TBARS (a marker of oxidative stress) were significantly lower, and total thiol levels (an antioxidant marker) were significantly higher in the fosinopril-treated groups compared to those without fosinopril treatment. In histopathological evaluations using a damage scoring system for edema, hemorrhage, and inflammation, scores were lower in the fosinopril-treated groups. Immunohistochemical analyses revealed that the expression levels of VEGF, collagen I, and collagen III were lower in the fosinopril-treated groups compared to the untreated groups at the same time points. This study demonstrates that fosinopril exerts antioxidant effects during the Achilles tendon healing process and provides favorable histopathological findings during the evaluated period of tendon healing.