580. ESTABLISHMENT OF A RAT MODEL OF GASTROESOPHAGEAL REFLUX DISEASE INDUCED CHRONIC MICROASPIRATION

Abstract Background Gastroesophageal reflux disease (GERD) is a common gastrointestinal disorder in Japan, the world’s first super-aging society. Occult microaspiration due to GERD can cause respiratory infections especially in frail elderly individuals. The aim of the study was to establish an experimental in vivo model of GERD induced chronic microaspiration. Methods GERD was induced in 8-week-old male Wistar rats. A 2-cm midline incision was made in the upper abdomen. The border between the forestomach and the glandular portion (limiting ridge) was ligated with a 2–0 silk tie, and the duodenum near the pyloric ring was covered with a 2-mm-wide piece of an 18-Fr Nélaton catheter. CT scan and histopathological evaluation of the bilateral lungs were performed at 3 weeks after surgery. Results The 3-week survival rate was 80% (n=4/5). CT scan showed diffuse dilatation of the esophagus due to the reflux of gastric contents; however, there was no consolidation in the lungs similar to the healthy control. Based on macroscopic evaluation, the lungs had multiple spotted redness. Histopathological evaluation of hematoxylin and eosin staining showed multiple spotted aspiration pneumonia with peribronchiolar inflammatory cells, granuloma formation, goblet cell hyperplasia. Conclusions This model mimics human occult chronic microaspiration due to GERD, and may be useful in the investigation of drug efficacy and the evaluation for pathophysiology of GERD induced pulmonary disorders.