ABSTRACT
Objective:To investigate the effect of erigeron breviscapus (EBHM) on ocular hypertension and the protective effect of retinal ganglion cells (RGCs) in rats by regulating mitogen activated protein kinase (MAPK) signaling pathway.Methods:Sixty male Sprague-Dawley rats were divided into control group, model group, low-dose EBHM group (group A), medium-dose EBHM group (group B), and high-dose EBHM group (group C) by random number table method. There were 12 rats in the group, the left eye was used as the experimental eye. The rats of model group, group A, group B, and group C were infused with normal saline through the anterior chamber to construct an acute ocular hypertension model; the control group was given general anesthesia only. Then, 2-30 days after modeling, rats in the control group and model group were given 3 ml of normal saline once a day; rats in group A, group B, and group C were given 0.30, 0.45, and 0.60 g/100 g EBHM by intragastric administration, respectively, 1 time/d. The rat intraocular pressure was measured before modeling and 1, 14, and 30 days after modeling, and the proportion of high intraocular pressure model was measured. Thirty days after modeling, hematoxylin-eosin (HE) staining was used to observe the pathological changes of retinal tissue; immunofluorescence staining was used to detect the changes in the number of RGCs; real-time fluorescent quantitative polymerase chain reaction (RT-qPCR) was used to detect p38 in the retinas of rats in each group. The relative expression of MAPK and Caspase-3 mRNA; western blot was used to detect p38MAPK and phosphorylation in the retina of rats in each group relative expression of phosphorylate-p38MAPK (p-p38MAPK) and Caspase-3 protein. One-way analysis of variance was used for multi-sample comparison, and SNK-q test was used for comparison between two samples. Results:One day after modeling, none of the rats in the control group developed acute ocular hypertension, and the other groups were successfully modeled. Compared with the model group, the rates of acute ocular hypertension at 14 days after modeling in groups B and C were lower ( χ2=98.701, P<0.05), and the rates of acute ocular hypertension at 30 days after modeling in groups A, B, and C were 0. There was no statistically significant difference in the rates of acute ocular hypertension between 14 and 30 days after modeling in the A, B, and C groups ( P>0.05). The results of HE staining showed that the structure of the retina in the control group was complete, and the layers were clearly visible; the RGCs count was not abnormal, and the morphology was plump and round. The retina of rats in the model group became thinner; the number of RGCs was greatly reduced, the morphology was vacuolated, and the arrangement was sparse. The retina of rats in groups A, B, and C became thicker, and the number of RGCs increased, and the retina structure in group C was better restored. The results of immunofluorescence staining showed that the RGCs counts of rats in groups A, B, and C were higher than those in the model group, and the difference was statistically significant ( F=297.514, P<0.05); pairwise comparison between groups, group A was lower than that of group B and C Group ( q=2.842, 5.263), group B was lower than group C ( q=2.457), the difference was statistically significant ( P<0.05). The results of RT-qPCR and Western blot showed that compared with the model group, the relative expression of Caspase-3 mRNA ( F=267.912) and protein ( F=692.279) and the relative expression of p-p38MAPK protein in the retina of rats in groups A, B and C. The expression level ( F=150.061) all decreased, and the difference was statistically significant ( P<0.05); pairwise comparisons between groups showed that Caspase-3 mRNA ( q=6.977, 15.642) and protein ( q=6.997, 15.642) relative expression levels and p-p38MAPK protein ( q=12.443, 24.358) relative expression levels are lower than groups A and B, group B was lower than group A ( q=11.678, 12.471, 10.204), the difference was statistical academic significance ( P<0.05). Conclusions:EBHM can significantly reduce intraocular pressure in rats with acute ocular hypertension, increase RGCs counts, and reduce retinal damage. Its regulatory mechanism may be related to the MAPK pathway.