Pretective Machenism Of Recombinant Human Erythropoietin On Retina Following Eye Contusion In Rats

ObjectiveThe present study is to aim at systemically reseach variations ofexpressions of Bcl-2and Bax and regulatory effect of rhEPO on the expressionsof Bcl2and Bax in retina by means of the ocular trauma model. These are all forfurther exploring protective effects of rhEPO on retina cells and layingfoundation on exploiting effective therapeutic measures on retina trauma.MethodsOf45two-month old male SD rats,5rats were obtained at random fornormal control group. The left eye contusions were made by modified Allen,sfalling strike for the rest40rats.successful model rats were randomly dividedinto model group and rhEPO group. Each group is subdivided into4groupsaccording to the different timepoint (12h，24h，3d，7d),5rats per group.TherhEPO group animals were intraperitoneally injected with rhEPO according to60IU/Kg per rat, once a day. The model group animals were injected withphysiological saline.The retina specimen were gotten after stopping givingrhEPO and physiological saline. Paraffin retins sections were made and thestructural changes of Each layer retina were observed with light microscope bymeans of HE staining, and the expressions of Bcl2and Bax were observed byimmunohistochemistry staining. Results1. Histopathologic changes of retina neuronsIn sham group, neurons were arranged orderly and intact in normal groups;the neurons in model groups and rhEPO groups were swollen, arrangedasymmetrically, the cellular inter-space widened, the volume of some cellsdecreased with nulear pyknosis and dyed darkly.2. Bcl-2protein assayThe results of immunohistochemistry staining for Bcl-2showed that theproducts of immunoreaction was brown under microscope. The expression ofBcl-2protein was found in ganglion cells layer, inner nuclear layer and outernuclear layer in normal groups. In model groups, the change of expression ofBcl-2protein was not obvious after12h. The expression of Bcl-2proteindecreased gradually, and reached minimum at3day after ocular trauma. Exceptfor12h, the expression of Bcl-2protein is lower in model groups than that innormal groups at each timepoint (P<0.05). In rhEPO groups, the changetendency of expression of Bcl-2protein was similar with model groups, but theexpression of Bcl-2protein was obviously higher in rhEPO groups than that inmodel groups at24h,3day and7day. The average optical density of positivecells for Bcl-2protein in rhEPO groups was higher than that in model groupsrespectively(P＜0.01).3. Bax protein assayThe product of immunohistochemistry staining for Bax protein was brownunder microscope. The expression of Bax protein was found in ganglion cellslayer, inner nuclear layer, outer nuclear layer and photoreceptor cell layer innormal groups. In model groups, the change of expression of Bax protein wasnot obvious after12h, and then the expression of Bax protein increasedgradually, and reached its peak at3day after ocular trauma. The expression ofBax protein was higher in model groups than that in normal groups after24h,3day and7day(P<0.01). In rhEPO groups. The change tendency of expressionof Bax protein was similar with model groups, but the expression of Bax proteinwas obviously lower in rhEPO groups than that in model group at24h,3day and 7day. The average optical density of positive cells for Bax protein in RhEPOgroups was lower than that inmodel group respectively（P<0.01）.ConclusionsBcl-2and Bax take part in pathologic process of ocular trauma; rhEPOregulates the expression of apoptosis factors of Bcl-2and Bax on retina cellsfollowing ocular trauma. Recombinat human erythropoietin can inhibt theapoptosis of retina cells from ocular trauma retina, which can protect and treatthe ocular trauma.