The Role Of Progesterone In Regeneration After The Optic Nerve Injury And Change Of GLT-1and Activated P38-MAPK

Objiective:The failure of the optic nerve to regenerate after injury remains a major clinical and scientific problem. Recent years, a lot of researches focus on nervous protection drug,but the progress is slowly due to the effects were limited and side reactions. Attention is now turning to drugs that act on multiple pathways to enhance survival and functional outcomes. Progesterone’s effects on the reproductive system are well known but it is only in recent decades that its neuroprotective effects have been identified. Progesterone could be synthesized and secreted in nervous system and plays active roles throgh multiple ways,such as lessening inflammation、suppressing cell apoptosis and promoting neurotrophic factors synthesize.The protective role of progesterone had been certified,but the effects for the optic nerve are not clear.In our study,mis-classification damage model of rats were made.Gave progesterone by intraperitoneal injection and observed the retinal morphology changes through HE staining and expression of glutamate transporter (GLT-1) and activated p38-mitogen activated protein kinases (p38-MAPK) changes in the retina through Semi quantitative detection of immunohistochemistry and postive cells counts at1、3、7、14day after the optic nerve injury.Intending to approach effects and mechanisms of progesterone in regenerate of the optic nerve after injury.We expected that this research would provide experimental evidence and theoretical basis of progesterone in the treatment of optic nerve injury.Methods:80male SD clean grade healthy rats,weighing200g+20g,with no pathological changes by examination of fundus and outer eye,were included in the experiment.Made4groups according to random check list:normal group, sham injury group,injury1group, injury2group,20rats in each group.There was no process in normal group;rats of sham injury group were exposured the right optical nerve,but not injury; rats of injury1group and injury2group were made mis-classification damage models with right eye. Rats of the injury1group were given physiologic saline(at8mg/kg dose) and rats of the injury2group were given progesterone injection(at8mg/kg dose) immediately by intraperitoneal injection once a day until the end of the experiment. At1、3、7、14day after injury,the right eyeball of5rats in the every groups were excised.The retina tissue was taken to be observed.we observed the morphologic changes of the retina of2mm long above optic papilla on the slices through HE staining,and immunohistochemistry for GLT-1and activated p38-MAPK.The datas were expressed by mean±standard deviation,and the statistical analysis was described by SPSS13.0software with One-way analysis of variance or One-Samples T Test,LSD-t test was used in group comparison.Results:1、Through He staining, the structure of retina was clearly,there were three nuclear layer:ganglion cell nuclear layer,inner nuclear layer and outer nuclear layer in normal group and sham injury group,the nuclear were all regularity.The retinal ganglion cells of injury1group were sparse and deranged with time extending,showing vacuolization.Inner nuclear layer and outer nuclear layer were thin in varying degrees. Compareing with injury1group,the retinal cell nuclears were regularity,the degree of rarefaction and vacuolization decreased,there was no obviously change for thickness of the retina.2、Immunoreactivities of GLT-1were observed predominantly in the inner plexiform layer and inner nuclear layer of rats’retina,and there was no difference in normal group and sham injury group. AOD of GLT-1in injury1group on1day was0.368±0.033,the differece with normal group had no statistical significance(P<0.05),to approach AOD of GLT-1in injury1group was higher than normal group that indicate expression of GLT-1in injury1group increased;AOD on3day、7day and14day were0.151±0.027、0.106±0.031and0.076±0.020,which were all lower than normal group (P<0.05). AOD of GLT-1in injury2group on1day was0.461±0.011,the differece with injury1group had statistical significance(P<0.05), to approach AOD of GLT-1in injury2group was higher than injury1group that indicate expression of GLT-1in injury2group was more than injury1group. AOD on3day,7day and14day were0.231±0.021、0.132±0.022、0.103±0.013,which were all higher than injury1group,but except AOD on3day was higher than normal group,AOD on7day and14day were lower than normal group,to approach the expression of GLT-1in injury2group was more injury1group but could not achieve the normal level.3、The immunity positive reactant of activated p38-MAPKwas not observed at various time points in the normal group and sham injury group.In injury1group,the immunohistochemical studies showed activated p38-immunoreact-ivities were mainly seen in the retinal ganglion cell layer on1day,3day and7day, AOD respectively were0.459±0.029、0.324±0.023and0.201±0.024, the positive cells counts of p-p38respectively were14.2±1.5、8.0±1.6and4.2±0.8,AOD and the positive cells counts decreased gradually, by14day, activated p38had virtually disappeared.AOD of injury2group on1day、3day and14day respectively were0.339±0.019、0.245±0.014and0.154±0.032, the positive cells counts respectively were8.2±1.3、6.4±1.1and3.4±1.2, the difference of AOD and the positive cells counts between injury2group and injury1group had statistical significance (P<0.05) for every time point,that indicated the expression of p-p38in injury2group was less than injury1group;we could not detect p-p38on14day.Conclusions:1、The structure of retina was clearly and the nuclear were all regularity;there was no obviously difference between normal group and sham injury group. The number of retinal ganglion cell reduced and was disorder after traumatic optical nerve injury. The condition of retina of injury2group was better than retina of injury1group.We could demonstrate progesterone play a role in protecting retinal ganglion cells after the optical nerve injury.2、The average optical density of GLT-1in injury2group was higher than injury1group, which demonstrate progesterone could induce increase of GLT-1in the retina after the optical nerve injury.3、The average optical density of activated p38-MAPK in injury2group was lower than injury1group,which demonstrate progesterone could induce decrease of actived p38-MAPK of the retina after the optic nerve injury.