Effects Of Ginkgo Biloba Extract On Mitochondrial Transmembrane Potentials In Retinal Ganglion Cell And Expression Of Heat Shock Proteins After The Optic Nerve Injury In Rats

Objective: Optic nerve injury is an optic neuropathy which leads tosevere visual impairments and poor prognosis. This kind of patients hold alarge proportion during the ophthalmology injuries, but the treatment is fewand the results are poor. To investigate the methods of repair and regenerationand to seek the strategy of improving optic nerve function are always hot spotsin researches. However, safe and effective drugs are absent at present. Moreand more evidence suggest that Ginkgo Biloba extract has multiple effectssuch as antioxidant, anti-ischemic, the protection of mitochondria and avariety of resistance to nitric oxide synthase, Glutamate toxicity and plateletactivating factor. There is no toxic and side effect during long-term follow-up.So Ginkgo Biloba extract is a potential visual function protectant forlong-term application.In our study, optic nerve injury model of rats were made. Afterintraperitoneal injection of EGb761, the change of mitochondrialtransmembrane potentials in retinal ganglion cell and the expression of heatshock proteins were observed in order to investigate the function of EGb761for optic nerve injury. Then,to provide the theoretical basis and experimentalevidence for clinical application.Methods:60healthy, clean SD rats (male and female is not restricted),weight250±10g, with no pathological changes by examination offundus and outer eye. Made3group according to randoml check list:normal control group (normal group) with20rats (20eyes), experimentcontrol group(control group) with20rats (20eyes), experiment treatmentgroup (treatment group) with20rats (20eyes). Control group and treatmentgroup set up the optic nerve damage model with no management in normal group. One hour after this, normal saline was injected intraperitoneally incontrol group and0.35%(100mg/kg) EGb761was injected intraperitoneallywith45mg/kg in treatment group every day. Administrate drugs after injury in3,7,14and28days, the5eyeballs in control group and treatment group. Theleft eyeball was operated as injury of optic nerve in control and treatmentgroup. Draw materials at the corresponding time point after operation forexperiment research. We observed the morphologic changes in retina and opticnerve with HE-staining, the expression of heatshock proteins27withimmunohistochemistry stain and results of mitochondrial transm embranepotentials in retinal ganglion cell with flow cytometry. Analyzed it with SPSS13.0statistical software, and expressed the results with mean±standarddeviation and percentage. Use variance analysis in measurement data andchi-square test in enumeration data.Results:1The results of HE retina in each groupIn the normal group, SD rats had layer, the kernel layer and the outernuclear layer of retinal ganglion cell under HE dyeing. Each layer of RGCsarranged compactly structure of RGCs clearly be visibled, and has distinct cellborders. Each time point, the arrangement was disordered and the number ofRGCs quickly reduced in control group. Some cells appeared edema andcavitation model change in injury early, along with the extension of time, itwas changed obvious sparse, thin, arrangement disorder in retinal ganglioncell layer of rats. The kernel layer and the outer nuclear layer was differentlevel to reduce. The same as treatment group, however, it was damaged lighterthan control group in each time point.2The results of immunohistochemistry stain HSPs27in each groupThe expression of HSPs27located in the kernel layer and the outernuclear layer, and the strong positive expression of HSPs27was brown. Thenormal group expressed slightly, and there was no significant difference intime point; the control group3d shows weakly positive expression,7d arecontinuously increased, damaged peaks at14d, and damage28d is decreased obviously to3d level; positive expressions in treatment group were lowerthan those in the control group but stronger than normal group.The results of immunohistochemical semi-quantitative detection: Theexpression of HSPs27in control group and treatment group weresignificantly high than that in normal group during each time point. Therewas significant difference(P>0.05) between them, and normal group3d,7d,14d and28d HSPs27was0.113士0.015、0.117士0.009、0.115士0.124、0.117士0.006; control group3d,7d,14d and28d HSPs27was0.424士0.031、0.538士0.073、0.337士0.022、0.252士0.014; treatment group3d,7d,14d and28d HSPs27was0.330士0.021、0.327士0.183、0.211士0.015、0.172士0.007. Each time point compared with normal groupdifference had statistically significant (P <0.05), and they were higher thannormal group; each time point compared with control group and treatmentgroup had statistically significant difference (P <0.05), and each time pointHSPs27of the treatment group was lower than that in the control group.3Flow cytometryRGC△ψm was3835.67±20.32in normal group; after damage,RGC△ψ m was3054.41±7.74、1821.07±18.66、2616.38±7.37、2835.37±8.48on3d、7d、14d、28d in control group.△ψm at each point intime was obviously low than normal group, and among these differenceswere significant(P <0.05). RGC△ψm was3355.41±6.634、2031.18±16.53、2718.27±6.25、3035.35±7.36on3d、7d、14d、28d in treatment group.△ψm at each point in time was obviously lower than normal group, buthigher than control group. Among these differences were significant (P <0.05).Conclusions:1The structure of retina was disorder and the numberof RGCs were decrease after optic nerve injury.2The expression of heat shock proteins27in retinal tissue wasascending and mitochondrial transm embrane potentials was descending afterinjury of optic nerve. 3With application of Ginkgo Biloba extract, the expression of heatshock proteins27in retinal tissue was descending and mitochondrialtransmembrane potentials was ascending.4EGb761took part in the retinal reparative process in optic nerveinjured rats.