| BackgroundThe damage to the ischemic tissue will aggravate after its blood flow restores. We define this phenomenon as ischemia-reperfusion injury. Retina ischemia-reperfusion injury not only is the initial factor of some eye diseases, but also is the leading cause of serious vision loss and even blindness. Among these diseases are: glaucoma, ischemic opticoneuropathy, choroid blood vessel obstruction, diabetic retinopathy, premature retinopathy, central retinal artery occlusion and traumatic retinopathy and other eye diseases.Somatostatin(SST) is a kind of physiologic hormone, which is secreted by the hypothalamus and consisted of fourteen amino acid peptides. SST can inhibit the release of pituitary hormone by combining with the somatostatin receptors on the cell membrane. Now we has separated five different types of somatostatin receptor(SSTR). And all of the five receptors can be detected in the retina, which reveals the complexity of SST in the retinal function. However, the half-life of SST is so short(only three minutes) that is not long enough for research and treatment. Octreotide is a member of the SST family, which has much more power than SST.At present, many researches shows that Octreotide can reduce the number of apoptotic retinal cells caused by IRI, can reduce the retina edema caused by IRI, leukocyte infiltration, and MDA content. But it still lacks system comprehensive report about the Octreotide protection function in the retina ischemia-reperfusion injury.ObjectivesTo establish eye retina ischemia-reperfusion injury model in mice induced by high pressure; To get knowledge of the Octreotide protection function in the retina ischemia-reperfusion injury;To explore the mechanism of Octreotide protection function in the retina ischemia-reperfusion injury.Methods:1.Group: 90 mice were used. 6 mice were used as control group, 42 mice were used as ischemia-reperfusion injury model group(I/R), and the other 42 mice which were pretreated by Octreotide as the experimental group(OCT+I/R). Model: Octreotide(50μg/kg) were used five times by intraperitoneal injection to these mice 15 minutes before IRI and at the times of 6h,12 h,18h,24 h after IRI. And we got the eye or retinal 4 hours after the last injection.2.Histological observation The eyeball was fixed with paraffin section, the retinal histologic changes were determined by HE staining, the degree of lack of ganglion cells and retinal thickness was determined by immunofluorescence staining; the apoptosis of retina was determined by TUNNEL staining; the ICAM-1 protein expression in retina was determined by Immunohistochemical staining; the GAFP expression was determined by retinal pave piece.3.The detection of ROS and MDAFirst make frozen section of the eyeball. The changes of oxygen free radicals in the retina were determined by ROS fluorescence probe-DHE. The detection of MDA was used to evaluate the degree of lipid peroxidation.4.Examining the contents of TNF-α、IL-6、MCP-1 and IL-10 of retina tissue homogenate with ELISA.5.Examining the gene expression of TNF-α、IL-6、MCP-1、IL-10、ICAM-1 and VEGFR with RT-PCR.6.Examining the protein of p65、ICAM-1、VEGFR、GAFP with Western Blotting.7.Determination of leukocyte adhesionPerfuse FITC-ConA through a cannula at the aortic root, then dissect the retina to get retinal preparationResults:1. In the early days of retinal ischemia reperfusion, the inner of the retina suffered severe edema, with cells appearring cavity; After some time edema faded, retinal got to become thin and suffer the loss of ganglion cells. While pretreated with Octreotide, the experimental group shows less injury.2. Compared with the IRI group, when pretreated with Octreotide, the experimental group shows lower TUNELpositive cells.3. Compared with the IRI group, Octreotide can reduce the level of ROS in retina. 24 h after reperfusion, the MDA in the retina tissue of the IRI group was much higher than that of the experimental group.4. RT-PCR and ELISA analysis suggest that IRI significantly increased the expression of mRNA of TNF-α、IL-6、MCP-1、IL-10 gene than the control group, while Octreotide could inhibit this trend to some extent. 24 h after reperfusion, the protein of p65、p-p65、GFAP、ICAM-1 were increased, while Octreotide could also inhibit this trend dramatically.Conclusions:1.Octreotide can reduce the injury of retina, the number of apoptotic cells and the loss of nerve cells after the retina ischemia-reperfusion injury.2. The study shows that Octreotide boost retina cells’ response to oxidative stress, intervent leukocyte adhesion, and regulate inflammation. |
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