Protective effect of cataractogenic lens injury on RGCs in optic nerve axotomy eye in vivo and its mechanism / 中华实验眼科杂志

ABSTRACT

Background It has been reported that murine Müller cells conditional medium can promote the survival of retinal ganglion cells (RGCs) and the regeneration of axons,and the survival rate of RGCs improve in the optic nerve axotomy eyes with cataractogenic lens injury in vitro.However,the interaction of Müller cells with pricking of lens in protecting RGCs is unclear.Objective The aim of this study was to investigate the role of Müller cells on survival of RGCs in the optic nerve axotomy with cataractogenic lens injury.Methods Forty-eight clean adult Wistar rats were randomized into sham operation group,optic nerve axotomy group and lens injury combined with optic nerve axotomy group.The optic nerve was exposed only in the rats of the sham operation group,optic nerve was completely transected at 3 mm behind the eyeball in the rats of the optic nerve axotomy group,and lens puncture and optic nerve axotomy were performed in the eyes of lens injury combined with optic nerve axotomy group.The rats were sacrificed at day 7 and day 14 after operation to prepare the retinal specimens.The RGCs were examined and counted by hematoxylin-eosin staining.Müller cells labeled by glial fibrillary acidic protein (GFAP) were counted using immunohistochemisty.Results The number of RGCs was (52.98 ± 1.90) /field and (51.81 ±3.09) /field on the 7th and 14th day in the sham operation group,without significant difference between them (t =0.910,P =0.378).The number of RGCs was significantly lower on the 14th day ([22.67±1.94] /field) than that of the 7th day ([36.61±1.69] /field) in the optic nerve axotomy group (t=15.312,P=0.000).Also,the number of RGCs was (50.76±2.77) /field and (35.69±1.80) /field on the 7th and 14th day in the lens injury combined with optic nerve axotomy group,showing a significant difference between the two timepoints (t =12.920,P =0.000).In addition,the RGCs number in the lens injury combined with optic nerve axotomy group was significantly higher than that in the optic nerve axotomy group both on 7 days and 14 days after operation (7 dayst =102.840,P =0.000; 14 dayst =164.020,P =0.000),and the number of RGCs was lower in the lens injury combined with optic nerve axotomy group than that of the sham operation group on day 14 (t =187.040,P =0.034).None of GFAP-labeled Müller cell was seen in sham operation group at both on 7 days and 14 days after operation,but a significant difference was found in the optic nerve axotomy group between the two timepoints ([29.38 ± 2.04]/field vs.[19.07 ± 2.14]/field ; t =-9.868,P=0.000).No significant difference in the number of the GFAP-labeled Müller cells was found in the lens injury combined with optic nerve axotomy group between 7 days and 14 days after operation([48.96±2.80] /field vs.[46.73±1.50]/field,t=1.987,P=0.067).In postoperative 7 days and 14 days after operation,the number of GFAP-labeled Müller cells increased in the lens injury combined with optic nerve axotomy group compared with the optic nerve axotomy group (7 dayst =-15.997,P=0.000; 14 dayst=-29.938,P=0.000).Conclusions In optic nerve axotomy with cataractogenic lens injury eye,the punctural injury of lens induce the activity of Müller cells and further promote the survival of RGCs in the cataratogenic lens injury combined with optic nerve axotomy rat eyes.