Effects of estradiol on retinal injury and pyroptosis-related pathways in rats with ocular hypertension
Objective To explore the injury process of retinal ganglion cells(RGCs)after glucocorticoid(GC)-in-duced ocular hypertension(OHT),as well as the protective effect and mechanism of estradiol(E2)in RGC injury in rats with OHT.Methods Atotalof36(36 eyes)12-week-old male Sprague-Dawley(SD)rats were randomly divided into the blank control group,the GC-OHT group,and the OHT-E2 group,with 12 rats in each group.Rats in the GC-OHT group and the OHT-E2 group were subconjunctivally injected with GC,while those in the blank control group were subconjuncti-vally injected with an equal volume of normal saline.Two weeks after modeling,in addition to being injected with GC,rats in the OHT-E2 group were also provided with E2 eye drops.Before modeling and 1,2,3,and 4 weeks after modeling,the intraocular pressure of rats in each group was measured.The visual acuity changes of rats in each group were detected by pattern electroretinogram(P-ERG)and flash visual evoked potential(F-VEP)4 weeks after modeling.After the eyeballs were removed,the distribution and number of RGCs in rats of each group were observed by immunofluorescence staining.Immunohistochemistry,Western blot,and real-time fluorescence-based quantitative polymerase chain reaction were used to detect the relative protein and mRNA expression levels of NOD-like receptor protein 3(NLRP3),cysteine aspartate prote-ase-1(Caspase-1),and gasdermin-D(GSDMD)in rats in each group.Results There was no statistically significant difference in the intraocular pressure of rats in each group before modeling(P>0.05).Compared with the blank control group,the intraocular pressure of rats in the GC-OHT group increased 1,2,3,and 4 weeks after modeling,and the differ-ences were all statistically significant(all P<0.01).Compared with the GC-OHT group,the intraocular pressure of rats in the OHT-E2 group decreased 3 and 4 weeks after modeling,and the differences were all statistically significant(all P<0.01).The P-ERG and F-VEP results showed that compared with the blank control group,the amplitudes of P50 and P1 waves of rats in the GC-OHT group decreased,and the differences were both statistically significant(both P<0.05).Com-pared with the GC-OHT group,the amplitudes of P50 and Pl waves of rats in the OHT-E2 group increased,and the differ-ences were both statistically significant(both P<0.05).The immunofluorescence staining results showed that compared with the blank control group,the number of RGCs of rats in the GC-OHT group decreased,and the difference was statisti-cally significant(P<0.001).Compared with the GC-OHT group,the number of RGCs of rats in the OHT-E2 group in-creased,and the difference was statistically significant(P<0.001).The results of immunohistochemistry,Western blot,and real-time fluorescence-based quantitative polymerase chain reaction showed that compared with the blank control group,the relative protein and mRNA expression levels of NLRP3,Caspase-1,and GSDMD in the retina of rats in the GC-OHT group all increased,and the differences were all statistically significant(all P<0.05).Compared with the GC-OHT group,the relative protein and mRNA expression levels of NLRP3,Caspase-1,and GSDMD in the retina of rats in the OHT-E2 group all decreased,and the differences were all statistically significant(all P<0.01).Conclusion GC-induced OHT can cause pyroptosis of RGCs,and E2 may alleviate the injury of RGCs in rats with OHT by inhibiting the pyroptosis-related NLRP3/Caspase-1/GSDMD signaling pathway.