A Study Of The Defense Mechanism Of Laryngeal Mucosa In An Animal Model Of Laryngopharyngeal Reflux

Part 1 Establishment and Evaluation of a Rabbit Laryngopharyngeal Reflux ModelObjective:To.establish and evaluate a rabbit laryngopharyngeal reflux model and investigate the association between LES dysfunction and reflux laryngitis with the model.Subjects and methods:Twelve healthy New Zealand albino rabbits (2.5-3.5 kg) were utilized in this study. The animals were divided into two groups. Eight rabbits underwent total cardiomyectomy to induce reflux, and the remaining four rabbits underwent a control sham operation. A laryngoscopy and a 24-hour intra-esophageal pH-metry were performed prior to surgery and again 2 and 8 weeks post-surgery. After the final laryngoscopy, all animals were sacrificed to obtain histological results.Results:Total cardiomyectomy significantly increased the reflux index (R1), the duration of the longest reflux episode (DLRE) and the total number of episodes that occurred in 24 hour post-surgery. No significant difference was observed in the Reflux Finding Score (RFS) between preoperative and 2-week postoperative rabbits (P=0.11). But there was a statistically significant change in the RFS before and 8 weeks after the induction of reflux from 4.6±0.9 to 8.3±3.6 (P=0.02). Submucous gland hyperplasia and inflammation were significantly increased in the reflux group compared to the control group.Conclusion:The results of this study suggest that chronic lower esophageal sphincter dysfunction is associated with reflux laryngitis in rabbits.Part 2 Dilated Intercellular Space in the Larynx and Esophagus of a Rabbit Reflux ModelObjective:In this study, we investigated histological and electron microscopic changes of the laryngeal and esophageal epithelium in an animal model of reflux to demonstrate:1. the association between laryngopharyngeal reflux (LPR) and gastroesophageal reflux (GER),2. the value of dilated intercellular space (DIS) as a marker of LPR.Methods:Eight New Zealand albino rabbits were utilized. Four rabbits underwent total cardiomyectomy to induce reflux. The remains underwent a sham operation as controls. The animals were sacrificed 12 weeks after surgery to obtain histological and electron microscopic results.Results:There were significant differences in the histological results between the study group and the control group in both the esophagus and the larynx (P=0.041 and 0.014). Significant changes in the intercellular space (IS) were observed between the study group and the control group in the esophageal and laryngeal samples (P<0.001).Conclusion:The results of this study suggest that LPR and GERD have a common mechanism and DIS is a morphologic marker of LPR in rabbits.Part 3 Esophageal and Laryngeal Expression of Claudin-3 and Occludin in a Rat Reflux ModelObjective:The aim of this study was to investigate the association between laryngeal expression of claudin-3, occludin and laryngopharyngeal reflux (LPR) in a rat reflux model.Methods:Eight Wistar rats were divided into two groups. Four rats underwent total esophageal myectomy to induce reflux, and the remainder underwent a sham operation as a control. All animals were sacrificed 12 weeks after surgery to perform tissue histology, immunofluorescence and western blot analysis.Results:Lymphocyte infiltration increased significantly in the study group in both esophageal and laryngeal samples (P= 0.001 and 0.002,respectively). Both esophageal and laryngeal expression of claudin-3 were significantly lower in the study group when compared with the the control group (P= 0.045,0.037 respectively).There is no significant difference in expression of occludin.Conclusions:The results of this study suggest that a decrease in claudin-3 could be a sensitive indicator of reflux laryngitis in rats.