Effects Of Aminoguanidine On Retinal Nerve Cell Apoptosis And The Expression Of INOS In The ROP

Objective: To research the effect of aminoguanidine(AG)on apoptosis in mice of oxygen-inducedretinopathy and preliminary investigate its mechanism, to provide the theory basis for the application of AGon Retinopathy of prematurity (ROP).Methods:80C57BL/6J mice aged7days in SPF were randomly divided into four groups (Each grouphave20mice and40eyes): normal group, high oxygen group, high oxygen saline group and AG treatmentgroup. In the normal group, mice were housed in normoxic conditions from postnatal day7(P7) to P17. Inother groups, mice were put into an oxygen-regulated chamber under hyperoxic conditions (75±2%O2) for5days and backed to normoxic conditions for another5days to establish the oxygen-induced retinopathy(OIR) model. In the AG treatment group, mice were treated with aminoguanidine hemisulfate (100mg/kgbody weigh, intraperitoneally) dissolved in physiological saline daily from P12until P17, and anequivalent amount of0.9%physiological saline was utilized at a same way in the mice of high oxygensaline group. Ten mice of each groups were randomly sacrificed to take the retina on both P14and P17. Toobserve the changes of the retinal neurons and count the number of vascular endothelial cells whichbreakthrough the internal limiting membrane.The apoptotic cells in retina were detected by TUNELmethod. The expression of iNOS in retina were detected by immunohistochemistry method. Electronicmicroscope was used to observe retinal ultrastructure change.Result: The TUNEL-positive cells were mainly locally in the inner nuclear layer and the ganglion celllayer of high oxygen group, and the P14significantly more than the P17. The number of TUNEL-positivecells in high oxygen group was significantly more than normal group (P<0.05); The number ofTUNEL-positive cells in AG treatment group was significantly decreased than high oxygen group (P<0.05).The iNOS immunoreactive neurons were mainly locally in the inner nuclear layer and the ganglion celllayer, and the P14significantly higher than the P17. There was no positive cells in the normai group. Therewas significantly higher iNOS expression in high oxygen group and the granules of brownish yellow in thecytoplasm significantly increased; The expression of iNOS in AG treated group was significantly weakerthan that in high oxygen group and high oxygen saline group(P<0.05).There were many vascularendothelial cells in high oxygen group on the P14, compared with the high oxygen group,the number ofvascular endothelial cells were decreased significantly(P <0.01) in AG treatment group.Under theelectronic microscope,we discovered the retinal neuronal membrane shrinkage,mitochdrial swelling orvacuolation,shorter crestige became shorter or disappeared,karyopycnosis,perinuclear gap became windererheterochromatin increased,endoplasmic reticulum in high oxygen group. Compared with the high oxygengroup,the growth of retinal neuronal was a slight improvement in AG treatment group.Conclusion: AG could protect the retinal neuronal of OIR,inhibited apoptosis and decreased theexpression of iNOS may be one of the mechanism.