ObjectiveTo investigate the expression and pathological significance of neutrophil elastase (NE) and mucin 5AC (MUC5AC) in chronic obstructive pulmonary disease (COPD) rats. MethodsA total of 60 male specific pathogens free Sprague-Dawley rats were randomly divided into model group and blank group, each with 30 rats. The number of goblet cells and the positive expression of NE and MUC5AC were compared between the two groups by hematoxylin-eosin staining, alcianblue-periodic acid Schiff staining and immunohistochemical staining. ResultsNo rats died accidentally during the experiment. The number of goblet cells was 57.93±7.79 in the model group and 6.80±3.19 in the blank group, and the difference between the two groups was statistically significant (t=−44.267, P<0.05). The median (lower quartile, upper quartile) of the positive expression score of NE was 0 (0, 0) in the blank group and 2 (2, 3) in the model group, the median (lower quartile, upper quartile) of the positive expression score of MUC5AC was 0 (0, 1) in the blank group and 2 (2, 2) in the model group, and the differences between the two groups were statistically significant (P<0.05).ConclusionsThe positive expression of NE, goblet cells, MUC5AC and mucus secretion in COPD model rats increases significantly. Perhaps NE and MUC5AC can be used as target interventions to inhibit mucus hypersecretion.