Experimental Study On Protective Effect Of Extract Of Ginkgo Biloba Leaves On Retinal Injury In The Continuous High Intraocular Pressure Rats

PARTⅠ:Objective To investigate protective effect of Extract of Ginkgo Biloba Leaves(EGb)on retinal ganglion cell layer neuron injury induced continuous high intraocular pressure(IOP) in rats.Methods Selecting 60 healthy Sprague-Dawley(SD)rats,randomly separate 6 rats into normal control group and separate 6 rats into EGb treating normal intraocular pressure(IOP) group(EGb200mg/kg·d). 48 rats were established chronic high IOP models of rats by cauterizing two episcleral veins in the left eye. Then 30 rats satisfying experimental level(IOP>26mmHg) were selected and were randomly divided into five groups.6 rats were physiological brine treating group(2ml/d), and the other 24 rats were divided into four experimental groups according to the dose of EGb.A group ( EGb50mg/kg·d ) ,B group ( EGb100mg/kg·d ) , C group(EGb150mg/kg·d)and D group(EGb200mg/kg·d). After the treating time of one month.Rats were sacrificed on schedule. Flat preparation of whole retinaes were stained with 0.5%cresyl violet and neuron counting in RGCL from both eyes of each rat were performed to evaluate neuron loss.Results1.Neuron counting from RGCL of normal control group:The mean of neuron counting of RGCL was(3491.2±11.9)/mm2 in the left eye and(3483.3±21.5)/mm2 in the right eye .There was no significant difference between the left eye and the right eye of normal control group(P﹥0.05).2. Neuron counting from RGCL of normal treated group: The mean of neuron counting of RGCL was (3477.0±14.6)/mm2 in the left eye and (3483.5±19.8)/mm2 in the right eye . There was no significant difference between the normal control group and normal treated group(P﹥0.05).3. Neuron counting from RGCL of treated group A: The mean of neuron counting of RGCL was (2193.3±18.4)/mm2 in the left eye and (3488.0±21.6)/mm2 in the right eye . Neuron counting from RGCL of treated groupB: The mean of neuron counting of RGCL was ( 2433.2±35.4 ) /mm2 in the left eye and (3483.2±22.5)/mm2 in the right eye . Neuron counting from RGCL of treated groupC: The mean of neuron counting of RGCL eye was(2665.5±43.3)/mm2 in the left and (3490.0±17.6)/mm2in the right eye . Neuron counting from RGCL of treated groupD: The mean of neuron counting of RGCL was (2881.2±24.7)/mm2 in the left eye and (3486.7±17.6)/mm2in the right eye . The difference was significant between the model eyes of every dose group and normal control group(P<0.05). The difference was significant between the model eyes and self-controlled eyes in every dose group group(P<0.05). The difference was significant between the model eyes about neuron counting from RGCL of every dose group(P<0.05).4. Neuron counting from RGCL of group treated by physiological brine: The mean of neuron counting of RGCL was (2145.3±24.5)/mm2 in the left eye and (3489.5±17.5)/mm2 in the right eye . The difference was significant between the physiological brine treating group and model eyes of every dose group(P<0.05).Conclusion1. EGb has no effect on neuron counting of RGCL when administered alone in normal rats.2. EGb has partial protective effect on retinal ganglion cell layer (RGCL)neuron injury induced continuous high intraocular pressure(IOP) in rats.PARTⅡ:Objective To investigate the protective effect of Extract of Ginkgo Biloba Leaves(EGb)on the activity of retinal ganglion cells(RGCs)in the continuous high intraocular pressure(IOP) SD rats.Methods 20 healthy SD rats were established continuous high IOP models by cauterizing two episcleral vessels in the left eye . Then 12 rats satisfying experimental level(IOP>26mmHg) were selected and were divided randomly into two groups ,A group(control group) and B group( EGb treated group) . 6 rats in each group. EGb was irrigated into the stomachs of rat in the treated group on the dose of 150mg/kg·d . The rat eyes were excised and made into eyeball samples after one month.The paraffin-embedded slides were stained with silver staining for nucleolar organizer region(AgNOR) to observe and count stained grains in RGCs nucleus.Results1. Stained grains of RGCs nucleus in model eye of the group A is(1.33±0.07)/cell,and the group B is (1.83±0.09)/cell, There was significant difference between group A and group B(P﹤0.05). Stained grains are more in the group B than the group A. Stained grains in RGCs nucleus of the high IOP with EGb treated subgroup were more than those of the simple high IOP eyes2. Stained grains were obviously decreased in the high IOP eye according to the normal IOP eye . Statistical significance was found between the high IOP eye and the normal IOP eye in the two group (P<0.05) .Conclusion1. Continuous high IOP in rats by cauterizing the episcleral vessels can result in the decrease of stained grains in RGCs nucleus.2. EGb may have partial protective effect in RGCs activity of high IOP rats.