| Objective: Optic nerve injury,clinical curative effect is poor, theregeneration and functional recovery has been an important problem in eyeclinical and scientific research. The present study mainly concentrated in theinjury early drug therapy. Although antioxidant, ganglioside on visual functionrecovery have certain effect, but the effect of factors such as drug side effects,Poor effects limit its wide application.Thus, it is progress slowly in theprotection of optic nerve injury research. Minocycline for the secondgeneration of semisynthetic tetracycline derivative, now with strongantibacterial effect is widely used in clinical. In recent years，a number ofstudies show that minocycline besides have anti-inflammatory and immunesuppression effect, in a variety of neurological diseases model shows certainneurons protection[1]. But the effects for the optic nerve injury are not clear,it is rarely read related research reports.In our study, optic nerve injury model of rats were made. Applicationminocycline to intervene,observed the protection of retinal ganglion cells andexpression of the retina microglia (surface markers for CD11b), tumornecrosis factor (TNF-α) at1,4,7,14day after optic nerve injury. Discuss theregeneration effect and possible mechanism of minocycline on rat of opticnerve injury, so as to search for a new drugs to promote the regeneration afteroptic nerve injury and broaden application of minocycline in the clinical.Then,to provide the evidence for clinical application.Methods:60male SD clean grade healthy rats,weighing(200±20)g,withno pathological changes by examination of fundus and outer eye,wereincluded in the experiment.Made4group according to randoml checklist:normal control group (normal group) with12rats (24eyes),experimentcontrol group (control group) and24rats (24eyes), experiment treatment group (treatment group) and24rats (24eyes). Control group andtreatment group set up the optic nerve damage model,1hour after this,balance normal saline,minocycline was injected intraperitoneally with45mg/kg in control group and treatment group every day. Draw materials afterinjury in1,4,7and14days, normal group three SD rats,6eyeball,the righteyeball of6rats in control group and treatment group. The retina tissue wastaken to be observed.We observed the morphologic changes and counted the number of RGCsof the retina of the2mm long above optic papilla on the slices through HEstaining,and immunohistochemistry for CD11b and TNF-α. The averageoptical density value was tested by computer image analysis, the higher of theAOD, the stronger of positive expression.All date were presented as mean±standard deviation,the statistical analysis were described by SPSS13.0software with One-way ANOVA within-group or paired-samples t-testbetween-group. P<0.05for difference of statistical significance, P<0.01asthere is a significant difference of statistically significant.Results:1HE staining of retinal tissue1.1Changes of morphologicalIn the normol 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, thenumber of RGCs quickly reduce in control group.Some cells appeared edema and cavitation model change in injury early, alongwith the extension of time, it was changed obvious sparse, thin, arrangementdisorder in retinal ganglion cell layer of rats. The kernel layer and the outernuclear layer was different level to reduce. The same as treatment group,however, it was damaged lighter than control group in each time point,eg, ratsretina nuclear was arranged in order,and,sparse degree and cavity changedlighter than control group.1.2Quantity change of RGCs The number of average RGCs was not obvious difference in normalgroup. The number of average RGCs on1day,4day,7day,14day were24.771±1.262、15.886±1.388、12.829±1.339、7.714±1.296in treatmentgroup,which were all higher than control group. number of RGCs of controlgroup and treatment group were tend to decline after optic nerve injury,thus,The treatment group were higher than those in the control group,all datashad Statistically significant meaning(P<0.05).2Immunohistochemical of CD11b and TNF-α in retina2.1Expression of CD11b in the retinaAOD of normal group was not obvious difference,AOD on1day,4day,7day,14day were0.291±0.013、0.482±0.027、0.217±0.008、0.146±0.012incontrol group,0.236±0.007、0.428±0.021、0.184±0.008、0.074±0.012intreatment group. According to the shown on, AOD of treatment group werelower than those in the control group(P<0.05).AOD of positive microgliasignificantly increased on1day,the most number of microglia expressed on4day,then,activation degree gradually declined in treatment group. At thesame time,AOD of treatment group and control group were higher thannormal group (P<0.05).2.2Expression of TNF-α in the retinaThe positive expression of TNF-α did not detected in normal group,TNF-α had significant positive expression on1day, peak on4day, there wasstill weakly expressed on14day. AOD of control group were0.505±0.134、0.758±0.144、0.360±0.029、0.196±0.093；AOD of treatment group were0.393±0.081、0.632±0.125、0.247±0.039、0.078±0.016.Thus,we knew, AODof the treatment group and control group were higher than normal group(P<0.05). the positive expression of treatment group was lower than controlgroup on4day (P<0.05), among there differences were significant(P<0.01).Conclusion:1The structure of retina was disorder and the number of RGCs weredecrease after optic nerve injury, minocycline could reduce the loss ofRGCs,and reduce the damage,We could demonstrate minocycline play a role in protecting RGCs after optic nerve injury.2Microglia was activated and expressed TNF-α after optic nerve injury.3Microglia protect organization in normal circumstances, microglia bebad to RGCs after optic nerve injury.4Microglia and TNF-α of the treatment group were lower than controlgroup in retinal tissue on1day,4day,7day,14day,which prove microglia andTNF-α take part in the injury and repair process of optic nerve injury.5AOD of CD11b and TNF-αdifferences which had statisticallysignificant (P<0.05),that demonstrate minocycline could inhibit activation ofmicroglia, reduce express of TNF-α, reduce the inflammatory reaction,alleviate the optic nerve injury. |
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