Study On The Effects And Its Mechanism Of Chinese Medicinal Herbs On The Rabbit Retina For Gentamicin-Induced Toxicity

ObjectiveTo investigate the toxic effect and its mechanism of rabbits' retinal especially vasculars by intravitreal gentamicin, then study the protective effects of Chinese medicinal herbs on this model, thereby to identify Chinese medicinal herbs which may be valuable as therapeutic agents for this and other diseases which have similar mechanism, such as retinal vascular diseases that are more difficult to study.Method1. Intravitreal inject of 100-3000ug of gentamicin in Dutch Belted rabbit eyes, examine changes in clinical findings, fluorescein angiography, retinal vascular digestion, histopathologic finding, electron microscopy, histochemical changes and computerized image amalysis.2. The rabbits intraoculated 500ug gentamicin were treated with xijiaodihuang tang, dexamethasone and saline, then examine above all changes when the treat was got for 7 and 14 days.Result1. Ophthaknoscopic studies of the retina after intravitreal injection of various doses of gentamicin demonstrated that retinal hemorrhage, edema, optic disc swelling, ocular pigmentation changes and so on.Prominent vascular nonperfusion throughout the retina, small foci of leakage from some retinal blood vessels, marked hyperfluorescence of the optic disc chould be seen on fluorescein angiography. Light and electron microscopy showed that retinalpigment epithelium had changes firstly, it ranked mussily, melanin content changed, mitochondrial swelling, and nuclear pyknosis. Photoreceptors showed cytoplasmic vacuolization, mitochondrial, then the nerve fiber layer swelled, its mitochondria was also swollen. There was a prominent inflammatory response on the surface of the internal limiting membrane, with infiltration of the retina by polymorphonuclear neutrophils and monocytes. The histochemical finding was the high degree of ICAM-1. The above all results was related to the dosage of getamicin and time. 2. The second dosage of the formular herb was more effective to this model, and its action could kept a long period. The large and small dosage of herb could only reduce the retinal hemorrhage. Dexamethasone could have obvious effect at the first 7 days, but for the longer period, it aggravated the inflammatory changes.Conclusion1. The effect induced by intravitreal gentamicin mainly showed acute retinal hemorrhage and ischemia Retinal pigment epithelium changed firstly, mainly showed mitochondrial swelling. Retinal vasculas had obviously inflammatory action, mainly caused by leukocytic plugging. 500ug gentamicin could caused a middle effect on rabbits' retina.2. As a classical formula herb, xijiaodihuang tang could partly protect the retinal and vasculars from the toxicity of gentamicin, having no obvious side-effect. It will be of great value of clinical practices of these similar diseases.3. The model of intravitreal gentamin had many common clinical signs and histophthologic changes with other ocular diseases, especially the retinal vasculity. Leukocytic plugging has been postulated as one of the possible mechanisms involved in the retinal capillary nonperfusion, further elucidation of the mechanism by which leukocytic plugging occurs in aminoglycoside toxicity could help study diseases like diabetic retinopathy and retinal vasculitis.4. Retinal pigment epithelium and its melanin had a important role on this model's machanism, further research of melanin may help to investigate the happens of this model and many ocular diseases, melanin also can be a new...