| Objective: To investigate the role and mechanism of VEGF in the forming of presyrinx state of experimental syringomyelia in rabbits, we estimated spinal cord edema degree of experimental syringomyelia induced by intra-cisternal injection of kaolin with dry-wet technique, and observed its development tendency. In the same time, the VEGF expression intensity in cerebral spinal cord fluid of control and Kaolin group was determined by Enzyme-linked immunoadsorbent assay (ELISA) and immunohistochemistry, its development tendency was observed too.Materials and methods: Forty Chinese white rabbits, weighting from 1.5 to 2.0 kg, were used in this study, and divided randomly into three groups: kaolin group (20 rabbits), physiological saline group(10 rabbits), shamed-operation group (10 rabbits), all rabbits of three groups were divided evenly into five subgroup at 5 time points (the first third seventh forteenth twenty-first day post-operation) once more. Under ketamine anesthesia (30mg/kg) ,0.6ml of 25% kaolin solution (37) was injected into the cisterna magnaafter 0.6 ml of cerebral spinal fluid (CSF) was withdrawn slowly from the cistern in all rabbits of kaolin group, while 0.6ml of 37 37 physiological saline was injected into the cistern in those of physiological saline group, and neither Kaolin solution nor physiological was injected in shamed group. At 1st 3rd 7th 14th 21th day after kaolin injection, the rabbits selected randomly from every group were anesthetized again, CSF was collected by cisterna acupuncture once more and stored at -40 after Centri-fugation 5 minutes at 2500r/m. the expression of VEGF in these CSF specimen assaied by ELISA was contrasted to that in CSF collected when the models were made. All animals were killed by transecting at junction of cervico-Thoracic cord, Then the brains and cervical cords were moved wholly and quickly, 4mm long cervical cords were cut from Q.2 segments , the wet weigh(W) was obtained with electronic balance (0.0001g) after clearing off carefully the arachnoid N kaolin deposition and water from surface, the dry weigh(D) was scaled after roasting for 24 hours in 110 thermostatic baker. Water content of spinal cord(%) can be obtained with formula: Water content (%) = (W - D ) / W X 100. The rest of specimens were fixed in 4% formaldehydum poly-merisatum for 48 hours, then embedded in the paraffin. H&E staining and immunohistochemistry were completed to the sections, immunohistochemistry stainning of tissue sections were analyzied by hi-sharpness color pathological photoprocessing system. The optical density and positive area of VEGF expression in cervical cord of Kaolin shamed-operation and saline group were detected. The expression of VEGF at different time points was compared with edema level of spinal cord at corresponding time point, while both of the development tendencys were observed .Results: All animals of kaolin group had shown depressed anorexia from the first to third day after acupuncture, most severely during the seventh and the fourteenth day in addition to having the highest mortality in this period; these symptoms but nervous symptoms were remissive after 2 weeks. All of the shamed and saline groups hadn't shown any symptoms at the same time point. Basing on the naked-eye observation at all time points, we can see the different level of cerebral spinal cord swelling , cistern stenosis and even emphraxis. A large amount of kaolin deposit in the subarachnoid space of dorsum and ventral brain stem and cervical cord could be stripped difficultly from spinal cord in more than 2 weeks after intracistern injection; the fourth ventricle was dilated due to obstruction of its outlets by the kaolin sediment, with slight hernition of the cerebellar tonsils and dilataltion of the central canal to some degree. At the same time the saline groups had shown the normal spinal cord subarachnoid space central canal and so on. The result of water content assay has shown that edema of spinal cord appeared at the 1 st day (68.35+0.7% )following kaolin i...
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