ObjectiveTo establish a simple and stable model of benign tracheal stenosis in SD rats by nylon brush scraping induced mechanical injury, and to observe the pathological changes of tracheal tissue at different time points after modeling.MethodsTwenty SD rats were divided into sham operation group (10 rats) and stenosis model group (10 rats) by random number method. Symptoms and survival conditions were observed, tracheal tissues were obtained, granulation tissue proliferation was observed, and stenosis indexes were measured and compared. Another fifteen rats were sacrificed at different time points (days 0, 2, 4, 6, and 8) after modeling. Tracheal tissues were obtained, HE staining and Masson staining were performed to observe pathological changes with time.ResultsThe survival rate of the sham operation group was 100% on the 8th day after operation, and the survival rate was 0% on the 8th day after operation in the stenosis model group. The difference in survival condition between the two groups was statistically significant (P=0.000 1) by Log-rank test. The stenosis index in the sham operation group was (6.12±1.78)%, and in the stenosis model group was (60.28±12.56)%. The difference in the stenosis between the two groups was statistically significant (P<0.000 01). HE staining results showed that the tracheal lumen was unobstructed and no granulation tissue hyperplasia or stenosis was found in the sham operation group. The epithelial mucosa was intact and smooth, and the cilia structure was clearly visible. It was a pseudo-stratified ciliated columnar epithelium, which was consistent with the characteristics of normal airway mucosa. While in stenosis model group, the lumen was significantly narrowed, and the stenosis was mainly caused by granulation tissue hyperplasia. No epithelial structure was observed, or epithelial structure was extremely abnormal. Masson staining showed that the fibroblasts in the injured site increased first and then decreased, and the collagenous fiber (blue) in the injured site gradually increased with time.ConclusionsA model of benign tracheal stenosis in rats can be successfully established by nylon brush scraping induced mechanical injury. The modeling method is simple, controllable and reproducible. The model can be widely used in the investigation of pathogenic mechanism for benign airway stenosis and efficacy exploration of new treatment.
ObjectiveTo observe the protective effect of etomidate (ET) on cultured retinal ganglion cells (RGC) with mechanical injury in vitro. MethodsNew Sprague-Dawley rat RGC was cultured in vitro and identified by double immunofluorescent labeling of Thy1.1 and microtubule associated protein 2. The cultured primary cells were randomly divided into control group, RGC scratch group, ET low dose group (1 μmol/L), ET medium dose group (5 μmol/L) and ET high dose group (10 μmol/L). The RGC mechanical injury model was established by using iris knife to culture cells in RGC scratch group and ET group with different concentration. Seven days after modeling, the RGC survival rate of each group was detected by cell count Kit 8 proliferation assay. The apoptosis rate of RGC was detected by Annexin Ⅴ/propyl iodide double staining. Single factor analysis of variance was used to compare the groups. The pairwise comparison between groups was tested by the least significant difference method. ResultsThe survival rates of RGC in RGC scratch group, ET low dose group, ET medium dose group and ET high dose group were (72.60±2.97)%, (73.73±1.14)%, (79.19±1.79)% and (83.88±0.94)%, respectively. The RGC apoptosis rates of control group, RGC scratch group, ET low dose group, ET medium dose group and ET high dose group were (5.08±0.17)%, (18.67±1.24)%, (17.96±0.74)%, (15.11± 0.56)% and (11.67±1.32)%, respectively. Comparison of RGC survival rate between groups: compared with RGC scratch group, the cell survival rate of ET low-dose group, ET medium-dose group and ET high-dose group was increased, and the difference between RGC scratch group and ET low-dose group was not statistically significant (P=0.728); the differences between RGC scratch group, ET medium dose group and ET high dose group were statistically significant (P＜0.001); the difference between ET medium dose group and ET high dose group was statistically significant (P=0.002). Comparison of apoptosis rate of RGC among groups: the apoptosis rate of RGC scratch group was significantly higher than that of control group, the difference was statistically significant (P＜0.001). Compared with RGC scratch group, the apoptosis rate of ET low-dose group, ET medium-dose group and ET high-dose group was decreased, and there was no statistical significance between RGC scratch group and ET low-dose group (P=0.869). The differences of apoptosis rate between RGC scratch group, ET medium dose group and ET high dose group were statistically significant (P＜0.05). The difference of apoptosis rate between ET medium dose group and ET high dose group was statistically significant (P=0.007). ConclusionET has neuroprotective effect on RGC cultured in vitro with mechanical injury, and the protective effect increases with the increase of ET dose in a certain range.