Establishment of a novel and effective reflux laryngitis model in rabbits: a preliminary study

To establish a novel and effective reflux model with a modified nasogastric aspiration tube and to investigate the association between different types of nasogastric aspiration tubes and reflux laryngitis, we conducted this study.

Thirty-eight healthy New Zealand albino rabbits (2.5-3.5 kg) were divided into three groups: control (CTR, n = 6)-non-intubated; normal nasogastric intubation (NNI, n = 16)-intubated with 4#, 6#, 8#, and 10# normal nasogastric aspiration tubes; and modified nasogastric intubation (MNI, n = 16)-intubated with 4#, 6#, 8#, and 10# modified nasogastric aspiration tubes. The laryngoscopy, body weight, and pH values at the esophageal entrance were recorded before and 1, 2, and 4 weeks after intubation. After the final laryngoscopy, the animals in groups with a pH below 4 were sacrificed to obtain histological and gene expression analysis results.

The reflux finding score (RFS) after 4 weeks showed that there was a statistically significant difference in the 8# NNI group (7 ± 0.816, P < 0.001), the 8# MNI group (11.5 ± 2.517, P < 0.001) and the 10# MNI (12.75 ± 1.893, P < 0.001) group compared with the control group (1.83 ± 1.602). The pH values of these three groups were lower than 4. However, the weight loss of the rabbits in the 10# NNI and 10# MNI groups was more obvious. Submucous gland hyperplasia and inflammation were significantly increased in the 8# NNI group, 8# MNI group and the 10# MNI group, but in the level of some pro-inflammatory cytokines and COX-2, the MNI group was significantly higher than the NNI group (8# NNI × 8# MNI, P < 0.01; 8# MNI × 10# MNI, P < 0.01).

This study showed that 8# modified nasogastric intubation (MNI) produces effective reflux laryngitis in the rabbits.