Treatment Of L-carnitine In Oxygen-Induced Retinopathy Of Prematurity In The Mice

Objective:to observe the pathogenesis of high oxygen-induced retinopathy after Established an animal model of Oxygen-Induced Retinopathy of prematurity. And then given the intraperitoneal injection of different doses of L-carnitine to mouse, to study whether L-carnitine can protect the retinal or not.Methods:Twenty-four 7-day-old C57BL/6J mice were randomly divided into normal control group,oxygen-induced retinopathy (OIR) group,low-dose drug therapy group and high- dose drug therapy group with 6 mices in each group. Except for the normal control group,the mice in the other groups were exposed to (75±2)% oxygen for 5 days, then went back to the normal air conditions for 5 days in order to establish a model of OIR.On 7th day postnatal,the treated groups were received intraperitoneal injection of different doses of L-carnitine,while the other two groups were received the same volume of Physiological saline. The pathological changes of retinal vessels of left eyes were observed by using the FITC-Dextran fluorescein angiography on 17th day, and Right eyes were made paraffin wax specimens also. After that, the parafin section which stained by hematoxylin and eosin were counted the number of endotheliocyte nuclei breaking through the internal limiting membrane by using the optical microscope. In addition, The expression of VEGF protein was assessed by immunocytochemistry assay. And The retina nerve cell apoptosis was assessed by the terminal deoxynucleotidyl transferase mediated Dutp nick end labeling (TUNEL) technique.Result:the Retinal vessels were observed distributing regularly in the two drug therapy groups compared with the oxygen control group with Non-perfusion areas also reduced. The number of endotheliocyte nuclei of new vessels extending out into vitreous in the oxygen group (33.85±2.53) were increased more significantly than the normal control group(0.4833±0.1169) (P<0.01). The number of endotheliocyte nuclei of new vessels extending out into vitreous were decreased more significantly in the two drug therapy groups (19.03±4.43)、(12.37±1.62) than the oxygen conthol group (F=76.059,p<0.01). besides, the two therapy groups have appeared reduced expression of VEGF greatly. The apoptosis number of the retina nerve cells in the two therapy groups were decreased more significantly than the oxygen conthol group (F=129.199,P<0.01).Conclusion:The animal model of oxygen-induced retinopathy was established successfully, based on which, we found that L-carnitine reduces the neovascularization and avascularization in the OIR. and also decreases the apoptosis number of retina nerve cells after high-oxygen indeced damage. as a result, L-carnitine appeared a protective effect on retina.The mechanism is related to the enhancing the activity of the antioxidant system,improving clearance of free radical and inhibiting cell apoptois...