Protective effects of Ginkgo biloba extract on morphology and function of retinal ganglion cells after optic nerve transection in guinea pigs

Abstract

To investigate the effects of Ginkgo biloba extract (EGb 761) on the morphology and function of retinal ganglion cells (RGC) in guinea pigs with optic nerve transection. Seventy-five albino guinea pigs were randomly divided into five groups: normal control group, sham-operated group, untreated group, normal saline group and EGb 761 group. No operation was performed in the normal control group. Optic nerve was merely exposed in the sham-operated group, but transected at 1.0 mm from posterior pole of the eye ball in the untreated, normal saline and EGb 761 groups. Guinea pigs in the EGb 761 group or the normal saline group received daily intraperitoneal injection of EGb 761 (100 mg/kg) or corresponding volume of normal saline from 7 days before experiment to 28 days after experiment. Three guinea pigs in each group were sacrificed for apoptosis assay (TUNEL method) of RGC. Pattern electoretinograms (PERGs) were recorded 14 and 28 days after transection, respectively. At the end of the examination, six guinea pigs were killed for histological examination and RGC count. No TUNEL-positive cells were observed in the normal control, sham-operated and EGb 761 groups, but there were TUNEL-positive cells in the untreated group and the normal saline group. The numbers of RGCs in the untreated and normal saline groups were less than those in the normal control and sham-operated groups at 14 days or 28 days (P<0.05). Although the number of RGCs in the EGb 761 group was less than those in the normal control and sham-operated groups (P<0.05), it was more than those in the untreated and normal saline groups (P<0.05). N(95) amplitude in EGb 761 group was higher than those in the untreated and normal saline groups (P<0.05) and close to those in the normal control and sham-operated groups (P>0.05) at 14 days or 28 days. The number of RGCs was positive correlated to N(95) amplitude (r=0.859, P=0.001 5). EGb 761 can inhibit the apoptosis of RGCs in guinea pigs after optic nerve transection, thus protect the morphology and function of RGCs.