Local injection of botulinum toxin type A (BTX-A) prevents scarring esophageal stricture caused by electrocautery in rabbit models

BACKGROUND: Benign esophageal strictures are common in clinical practice. The commonly used methods for preventing benign esophageal strictures still have many shortcomings. In this study, we investigated the preventive effect and possible mechanism of endoscopic local injection of botulinum toxin type A (BTX-A) on scarring esophageal stricture caused by electrocautery in rabbit models, with an attempt to provide a theoretical basis for the clinical application of BTX-A in the prevention of benign esophageal stricture. METHODS: Adult male New Zealand rabbits were randomly divided into 4 groups: cautery group (cauterized with 30 W electrocoagulation power without other intervention), saline group (injected with normal saline at 4 spots in the local esophagus after modeling), BTX-A I group (injected with 10 U of BTX-A after modeling), and BTX-A II group (injected with 20 U of BTX-A after modeling). Body weight was measured at postoperative weeks 1, 2, and 4. Esophagography was performed, and the internal diameter of the esophagus was measured. The esophageal tissues were harvested for hematoxylin and eosin (HE) staining and Masson staining. Type I, type III collagen levels and the mRNA expression of transforming growth factor β1 (TGF-β1) in esophageal tissues were detected. RESULTS: Compared with the cautery and saline groups, the BTX-A I and BTX-A II groups had significantly higher body weight, larger esophageal internal diameter, lower type I and type III collagen levels, and lower TGF-β1 mRNA expression levels in esophageal tissues at postoperative week 4. Comparisons between the BTX-A I and BTX-A II groups showed no significant differences in terms of body weight, esophageal internal diameter, and type I collagen level at postoperative week 4. However, the BTX-A II group had a significantly lower type III collagen level and TGF-β1 mRNA expression level than the BTX-A I group. CONCLUSIONS: Local injection of BTX-A can alleviate esophageal stricture after electrocautery and has a preventive effect on benign esophageal stricture caused by electrocautery in rabbits. The mechanism may be that BTX-A down-regulates the expression of TGF-β1 in the esophageal tissue at the burn site and reduces the deposition of collagen.