Ultrasonic Microbubbles And Memantine Can Protect Rat Retinal Ganglion Cells After Optic Nerve Injury

Objective To observe the protection effects of ultrasonicmicrobubbles combined with memantine on rat retinal ganglion cells(RGCs) after optic nerve injury.Method Forty SD adult male rats were randomly divided intonormal control group(group A), sham operation group(group B), blankcontrol group(group C), memantine group(group D) and memantine andultrasonic microbubbles group(group E),8rats in each group. Then A-Egroups were randomly divided into1week subgroup and2weeks subgroupafter the optic nerve injury,4rats in each subgroup. Group A had nointerference treatment. The optic nerves in group B eyes were exposed butnot clamped. Normal saline was injected into the vitreous, and those eyeswere immediately radiated with ultrasound. The optic nerves in group C-Ewere exposed and clamped to establish the optic nerve clamped models.Normal saline was injected into the vitreous of group C eyes; memantinewas injected into the vitreous of group D eyes; ultrasonic microbubble andmemantine was orderly injected into the vitreous of group E eyes and those eyes were immediately radiated with ultrasound. One week and2weeksafter the optic nerve injury, RGC was labeled by retrograde fluorogold（FG） to count the RGC number; flash visual evoked potential(F-VEP)was used to record the incubation period and the amplitude of P100wave;fluorescence microscopy was used to observed the pathologicalmorphology change of retinal cell.Results There were gold-labeled RGCs on the retina of group A-E.The difference of RGC count was not statistically significant betweengroup A and B(q=0.018,0.011，P=0.986,0.873). Compared to group A, theRGC count in group C-E were decreased significantly(F=85.944，P=0.012).The RGC count in group D was significantly higher than that in groupC(q=1.721,1.924;P=0.043,0.037). The RGC count in group E wassignificantly higher than that in group C andD(q=1.128,1.482,P=0.027,0.008;q=1.453,1.855,P=0.031,0.010). F-VEPshowed that there was no statistically significant difference of incubationperiod and amplitude of P100wave between group A and B（q=0.008，0.019，P=0.981,0.946；q=0.072,0.052，P=0.737,0.851）. Compared to groupA, the incubation period were lengthened and the amplitude were decreasedin group C-E with statistically significant（F=134.312，F=106.312，P=0.017,0.009）. Observed under the electron microscope, the retinalstructure of group A, B eyes was normal, but there were varyingdegrees of edema and thickening, RGC loss in group C-E eyes. Conclusions Memantine and ultrasonic microbubble can inhibitthe rat RGC loss after optic nerve injury, and improve the visual function.