动物造模,视网膜静脉阻塞动物模型 z-bio 2021-12-21 808

　　1 Photodynamic method

　　(1) Reproduction method Miniature pigs weighing 8-10kg are anesthetized by intramuscular injection of compound ketamine at a dose of 0.1ml/kg body weight, compound tropineamide is used to dilate the pupils, and the head is fixed on the head. Perform a scleral puncture on the flat part of the ciliary body above the nose, and insert the optical fiber (output power 10mw) for the intraocular illumination of the vitrectomy machine. Push Bengal Rose (20mg/kg body weight) into the ear vein, and use the optical fiber (the other end of the serpentine tube is fixed on the operating table to maintain the stability of the optical fiber) directly irradiating the 0.5-1.0 interpupillary distance above the optic papilla after 1 min. PD) of the main retinal vein. Avoid the accompanying arteries and irradiate for 10 to 15 minutes. It can be seen that the local white thrombus is gradually formed in the vein, the blood flow is blocked, and the distal end of the vein is fibrillated.

　　(2) Model characteristics In the process of retinal vein thrombosis, visible light chemical damage to the retina and choroid in the light-irradiated area is manifested as local retinal small blood vessels and choroidal vascular occlusion. Local tissues turned white, and fluorescein fundus angiography showed no fluorescence filling. With the formation of retinal vein thrombosis, it can be seen that white plaques in the blood vessels gradually accumulate, fall off, and reassemble until a thrombus is formed, blocking blood flow. 24 hours after thrombosis, the thrombus fills the entire vascular cavity, and its main components are platelets, red blood cells and neutrophils; extensive hemorrhage and edema of the retina involve all layers of the retina. Retinal hemorrhage and edema increased significantly on the 7th day after the operation. The nerve fiber layer and the inner (nuclear) plexiform layer were obvious, with gaps or cysts, and capillary congestion accompanied by inflammatory cell infiltration. After 1 to 4 weeks, the retinal nerve fiber layer and inner nuclear layer hemorrhage and edema are gradually absorbed, a large number of red blood cells remain between the photoreceptors and the pigment epithelium, the retinal layer is disordered, and the outer nuclear layer shows fold-like changes. Under the electron microscope, the inner retina was degenerated and necrotic, and the mitochondria in the cytoplasm were swollen and disintegrated.

　　(3) Comparative medicine Retinal vein occlusion is a common eye disease, which can cause complications such as macular edema, vitreous hemorrhage, retinal detachment and neovascular glaucoma, resulting in decreased vision and even blindness. The experimental retinal vein occlusion model prepared by this method can observe all the dynamic processes of thrombosis. After thrombosis, retinal vein fibrillation, stagnant blood flow, retinal edema and extensive hemorrhage can be seen. In this model, the optical fiber in the eye is used as the excitation light, combined with rose bengal to induce retinal vein occlusion. Although it is an invasive method, it is simple to operate and accurate, and thrombosis is reliable. It is a better method to prepare experimental retinal vein occlusion models.

　　2 Laser method

　　(1) Reproduction method Healthy adult rhesus monkeys weighing 6.0-7.0 kg are given intramuscular injection of ketamine hydrochloride at a dose of 1 to 2 mg/kg body weight for general anesthesia, and 10% fluorescein sodium is rapidly injected into the superficial vein of the forearm with 1 to 2 ml. After the corneal surface anesthesia of both eyes with 1% diacaine, the upper and lower main retinal veins were directly photocoagulated with an argon blue-green laser (488514nm) through a three-sided mirror. Laser photocoagulation accurately focuses on the vein when sealing the vein to avoid damage to the adjacent arteries. The length of the blocked vein segment is about 1DD, until the blocked vein segment becomes thin and white, the blood flow is stagnant, and the distal end tortuously expands.

　　(2) Characteristics of the model 24 hours after the operation, extensive hemorrhage and edema of the retina mainly in the posterior pole involved all layers of the retina. Congestion of the inner retinal vein, damage to the vascular endothelial cell wall; vacuolar degeneration, fiber breakage in the nerve fiber layer; reduced ganglion cells, disordered arrangement, looseness, and size abnormality; loose inner nuclear layer, vacuolation, partial absence, and outer plexiform layer void Bubble degeneration, edema, and sparseness. Retinal edema and thickening are the most serious in the outer plexiform layer near the macular area, which is 1 to 2 times thicker than normal. The inner plexiform layer has the least changes; the retinal pigment epithelial layer remains intact; deep hemorrhage in some areas of the posterior pole penetrates between the outer nuclear layer and the pigment epithelium layer, forming a localized neuroepithelial hemorrhagic detachment. Extensive edema of the inner retina, especially intracellular edema. The extracellular segment of photoreceptor cells is enlarged, the horizontal arrangement of the disc membrane disappears and becomes disordered; nerve fibers are enlarged and vacuolated, ganglion cells and bipolar cells are significantly swollen, mitochondria in the cytoplasm are enlarged, and the endoplasmic reticulum is slightly to moderately expanded; The Müller fiber serosal space in the nerve fiber layer and the ganglion cell layer and the neurite space in the inner and outer plexiform layers are significantly enlarged, and even cysts are formed. There are reticular exudates inside, and some of the protrusions are broken and collapsed. solution.

　　(3) Comparative medicine The rhesus monkey is selected for this method because its retinal blood supply system is very similar to that of the human eye. The argon laser can be absorbed by hemoglobin. When the retinal vein is photocoagulated, the heat effect produced by the hemoglobin absorbing a large amount of light energy causes the blood vessels to narrow and occlude strongly. Blocking a vein affects at least 1/2 area of retinal tissue. The affected area shows congestion and distortion of the retinal vein with edema and hemorrhage of the retinal tissue. If 10% sodium fluorescein solution is injected intravenously before photocoagulation, the absorption of light energy in the photocoagulation area can be increased to enhance the photocoagulation effect. The causes of retinal vein occlusion in the human eye are very complicated. The patients are mostly middle-aged and are often caused by a variety of factors, such as changes in blood vessel walls, changes in blood fluidity, and changes in hemodynamics. The experimental animals in this model were young and healthy, and the obstruction occurred suddenly in the original healthy vascular bed. However, despite these differences, Fundus Fluorescein Angiography (FFA) and histological examination both confirmed the retina after 24 hours of photocoagulation of the retinal vein. There are a series of typical clinical and pathological manifestations of retinal vein occlusion such as hemorrhage, edema, blood flow stasis, and microvascular dilation and leakage, indicating that laser photocoagulation alone can establish an ideal retinal vein occlusion animal model.