| Glaucoma is a group of diseases characterized by optic atrophy and visual field defect.Pathologically elevated intraocular pressure(IOP)is the main risk factor for glaucoma.Retinal ganglion cells(RGCs)loss is the common pathophysiological pathway of glaucoma.Curcumin has anti-inflammatory,antioxidant and neuroprotective effects.The aim of this study was to investigate the protective effects and mechanism of curcumin on RGCs in acute and chronic glaucoma models in rats.Part I:Objective:To study the protective effect of curcumin on rat primary retinal neurons(PRN)in vitro.Methods:PRN culture,oxygenglucose deprivation(OGD)model establishment,PRN viability was detected by CCK-8.Results:Curcumin(2.5-40 uM)enhancing the viability of PRN in vitro,and curcumin(10-40uM)enhancing the viability of PRN in OGD model of PRN.Conclusion:Curcumin has protective effect on PRN and OGD-injured PRN in vitro.Part II:Objective:To study the protective effect and mechanism of curcumin on retinal ganglion cells(RGCs)in acute ocular hypertension(AOH)rats.Methods:AOH model was established,RGCs were retrograde labeled with fluorogold(FG)and counted,RGCs apoptosis was detected by TUNEL staining,and proteins were detected by western blot(WB).Results:Seven days after AOH,the RGCs density in the control group was(2302±163)per mm2,whilethat in the AOH group was(960±105)per mm2,the survival rate of RGCs in AOH group was about 41.7%(P<0.001).The RGCs density in the curcumin treated group was(1864±159)per mm2,the survival rate of RGCs was significantly higher than that in the AOH group(P<0.01).Twenty-four hours after AOH,retinal TUNEL staining showed that RGCs apoptosis in AOH group,while curcumin treated group was significantly lower than that in AOH group.Retinal WB results showed that the expression of promoting autophagy protein beclinl,LC3-II and the ratio of LC3-II/LC3-Iincreased in curcumin group,while p62 was down-regulated.The expression of negative-relatedapoptosis protein bcl-2 was up-regulated,while the expression of promoting apoptosis protein bax was down-regulatedand the ratio of bax/bcl-2 was reduced(P<0.01).These changes were weakened in the autophagy inhibitor groups.WB results showed that curcumin-induced autophagy may be mediated by Akt/beclin 1/LC3 signaling pathway.Conclusion:Curcumin promotes auophagy to inhibit RGCs apoptosis in rat retina.Part III:Objective:To study the protective effect of curcumin on RGCs inchronic ocular hypertension(COH)rats.Methods:COH model was established,IOP was monitored by Tono-Lab,RGCs were retrograde labeled with FG and counted,optic disc changes were observed by hematoxylin eosin(HE)staining,and optic nerve(ON)changes were detected by transmission electron microscopy(TEM).Results:IOP fluctuation ranged from 17 to 46 mmHg in COH eyes within 12 weeks,while IOP remained from 10 to 15 mmHg in control eyes(P<0.01).Compared with the control group,the number of RGCs in COH eye decreased significantly.The loss rate of RGCs was 11.66%,32.87%,56.24%and 67.38%in the 2nd,4th,8th and 12th week after COH.The results of HE showed that the depression of optic papilla could be observed in COH eyes at 4,8 and 12 weeks after modeling compared with control eyes.Under transmission electron microscopy(TEM),compared with the ON of the control,the axons of the ON in COH eye were irregularly arranged and surrounded by proliferated glia.The density of axons of the ON was significantly reduced.The number of axons in the COH group was(41.6±6.09)per mm2,while the number of axons of the control ON was(132.7±7.1)per mm2(P<0.001).In the curcumin treatment group,the density of RGCs in COH eyes was significantly higher than that in the control group(P<0.01),indicating that curcumin can inhibitsRGC loss in COH model.The results of RG-labeled RGC counting showed that the RGCs density of COH eyeball in curcumin(10 mg/kg)treated group was 1581±194 per mm2,which was significantly higher than that in control group 969±173 per mm2(P<0.01),and the survival rate increased from 44.53%to 74.32%.Conclusion:Injecting conjunctival stromal cells into the anterior chamber of rat is aneffective animal model for chronic glaucoma.Curcumin has obvious protective effect on RGCs in COH ratsSummary:RGCs death is the common pathway for glaucoma,and RGCs are the target cells for glaucoma treatment.Curcumin has obvious protective effects on RGCs/PRN in OGD,AOH and COH models.This study further improves the mechanism of glaucoma physiological and pathological processes and provides a research basis for the clinical application of curcumin in glaucoma,which is importance for the prevention and treatment of glaucoma. |
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