| Background and Objectives : Retinal ischemia is a serious and common clinical problem. It occurs as a result of acute vascular occlusion and leads to visual loss in a number of ocular diseases such as acute glaucoma, diabetic retinopathy, and hypertensive vascular disease. Now, it is considered that energy depletion, intracellular Calcium overload, the excessive produce of excitatory amino acids and oxygen free radical, the insufficiency of all kinds of neurotrophins, the activation of apoptosis gene are the insult pathogenesis .Among these factor, the activation of apoptosis gene are postulated to play central roles. erythropoietin is a multifunctional protein of about 34000kD that is produced and secreted mainly by the kidney in adults and by the liver during fetal stages and that is present in serum. there is evidence that erythropoietin can cross the blood–brain and blood–retina barriers. we want to study if postishchemic treatment with EPO can ameliorate ischemic retinal injure. and to observe the express of apoptotic correlative gene caspase-3 in rabbit retinal ischemia-reperfusion injury , and to study the effect of EPO on them for investigating the neuro-protection mechanism of EPO .Method: 1.Making of the rabbit model : the rabbit's retinal ischemic model was induced in intraocular pressure to 110mmHg( 14.67KPa ) by perfusing the normal saline into anterior chamber and maintained 2 hour . The rabbits were divided into normal group,saline group and EPO group randomly, In a separate set of experiments, normal saline and rHEPO, were administered i.p. starting 5 min after the induction of the onset of ischemia injury and repeated every 8 h for 72 h, r-Hu-EPO was given to rhEPO treated groups at a dose of 1,000 units/kg. 2. Detection of ERG: Selecting Twelve healthy New Zealand rabbits and dividing randomly them into 3 group rats normal group, saline group and EPO group randomly.the two eyes of every rabbit were experimental eyes, and the wave of ERG of the model eyes in the 3 group were recorded respectively before , during ischemia and also at the 12h, 24h, 72h after reperfusion. 3. injury was also evaluated morphologically by counting the apoptosis cell on retinal slide between the EPO group and saline group by TUNEL method .4.compare the morphological difference among normal group, saline groups and the EPO-treated group on paraffin-embedded retina sections, the electron- microscope was also used to look into the difference between the saline groups and EPO groups .5.the expression of caspase-3 of different time courses was determined by SABC immunohistochemistry.Results: 1.the changes of amplitude of b-wave of ERG: the b-wave amplitude in the recovery in EPO treated groups tend to be higher than those of the saline group and the EPO group is more significant. 2.The thickness and morphological layer of the retina of EPO groups were better than those of the saline group after H.E.staining during all the post -reperfusion stages. 3.No TUNEL—positive cell was seen in the normal group and there were less apoptosis cells(P <0.01)in EPO group than those in ischemia group at each time point after reperfusion; the apoptosis retina ganglion cell in the saline group are more than in the EPO group. 4.The expression of caspase-3 protein at each time points after ischemic reperfusion between EPO group and saline group was significantly different(P<0.01).Conclusion: 1. EPO can reduce the expression of caspase-3 protein, the down—regulating of caspase-3 expression might contribute to the protective mechanism.2. it is true that some retinal gonglion cell are loss by apoptosis. and EPO can reduce the apoptosis of neurons after retinal ischemia3. EPO can protect the ischemic retina in part, and it is helpful to recover the function of retina.4. the high ocular pressure model is a convenient and effective way to research RIR . |
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