| With the development of medical technology, ionizing radiation has been widely anddeeply in clinical practice. For example, by using a variety of different tumor irradiationdose to inhibit and kill cancer cells, to achieve the purpose of tumor radiotherapy. However,radiation therapy induced peripheral nerve injury incidence is increasing, to some extent,affect the quality of life of patients, and thus radioactive peripheral nerve injury more andmore people’s attention and attention. After many scholars at home and abroad study foundthat radiation caused by neurovascular injury and perineural fibrosis, making nerveischemia, hypoxia, resulting in axonal degeneration and demyelination, resulting in nerveconduction disorders, and radiation dose is the main factor affecting the incidence ofbrachial plexus injury. The traditional view that any dose of ionizing radiation are harmfulto the body (LNT theory), but this theory has been challenged by low doses of ionizingradiation hormesis (LDL) generated. Foreign scholars have long started to notice therelationship between ionizing radiation and the surrounding nerves. Some researchers alsoreported the formation of ionizing radiation after epineurium inhibit scarring, and inregulating osteoblast differentiation and to play a role in bone remodeling. By readingexperimental findings of many scholars for years, it is not difficult to find that, on theeffects of ionizing radiation on the surrounding nerves, scholars research is controversial,one of which is around the dose of ionizing radiation as well as the pros and cons of theissue.Objective：This experimental design through various low-dose ionizing radiation (LDI)irradiation of normal rat sciatic animal model to observe changes in the structure andfunction of rats after different doses of ionizing radiation normal sciatic nerve, aimed atfinding out the structure and function of peripheral nerve damage to a minimum, worsebeneficial suitable dose of ionizing radiation in order to provide a theoretical basis forclinical treatment． Methods:March aged96Sprague-Dawley rats weighing200-250g, were randomly divided intosix groups, each16. Normal control group (A group did not receive any dose of ionizingradiation),0.2Gy dose group (group B to receive a single dose of0.2Gy irradiation, thefollowing groups and so on),1Gy dose group (group C),7Gy dose group (D group),14Gydose group (E group),20Gy (F group). Each group was randomly divided into six weeksafter radiation,12weeks2subgroups were drawn from observation. Carried out by X-raylinear accelerator local irradiation (dose rate200cGy/min, the irradiated area5.0×3.0cm:length×width, source skin distance (SSD)=100cm, imitation leather pad1.5cm), and theremaining parts of the stereotype protection. After irradiation, the animals left lower limbwas observed weekly gross morphology (such as local skin, hair condition, gait andstanding, etc.) and gait analysis. After irradiation for6weeks,12weeks, respectively, from6to remove eight groups of rats, through the general state of the light microscope grossmorphology, sciatic index, motor nerve conduction velocity, histological andimmunohistochemical, ultrastructural nerve transmission electron microscopy To comparethe six groups sciatic nerve function and structure changes.Results：1.after irradiation on the left lower limb function in each group showed noabnormalities, B, group C rats gait and standing with no significant difference betweengroup A, and toe were no local skin ulcers, but D, E, F rats left leg adverse varying degreesof hair growth, sparse, F group is most obvious.2.light microscope, the surface of the rat sciatic general observation: after irradiationsix weeks and12weeks, A, B, C, D groups sciatic nerve was silver-white, smooth, noadhesion with the surrounding tissue, the surrounding tissue without edema. One group ofrats had an E granulomatous inflammation around the sciatic nerve in6weeks afterirradiation, F will be a group of rats in a six weeks after irradiation.3. Each group of rats sciatic index: after irradiation for6weeks,12weeks, the ratsperformed our footprint analysis found that when rats steady gait, footprints clear.Footprint analysis of the measured index of rat sciatic nerve in each group and found nosignificant difference in the value of each group, B, C, D, E and F in five groups of ratswith sciatic functional index A group difference was not statistically significant (p>0.05).4.Nerve electrophysiological testing: A, B, C three groups of nerve conduction velocity, compound action potential amplitude and latency of no significant difference, D,E, F group, nerve conduction velocity was less than the control group. Where E, F groupconduction velocity was slower than in group A, and the difference was statisticallysignificant (P <0.05).5.Under HE staining and anti-S-100staining observed optical microscope: B, GroupC sciatic nerve fibers are arranged regularly, no connective tissue dysplasia or decrease.Group D Most of nerve fibers arranged regularly, sometimes disorganized, curl, E sciaticnerve disorder, most were curled, occasional myelin vacuolation, F myelin vacuolationgroup of nerve fibers, or axons disappear degeneration, inflammatory cell infiltrationaccompanied by focal hemorrhage, necrosis. Each group had no significant performanceSchwann cell proliferation.6.TEM ultrastructure observation: A, B, C sciatic nerve myelin fibers were round oroval, the shape, dense lamellar row vertical, thick, no demyelination and axonaldegeneration, seen around the snow Schwann cell proliferation. Group D myelin sheath ofnerve fibers began to appear irregularly shaped, plate thickness is thin, partially separated,demyelination of nerve fibers than the E, F group less obvious Schwann cell proliferation.E, F group myelin irregular shape, plate thickness is thin, most isolated, showingdemyelination and axonal degeneration, Schwann cell proliferation is not obvious.12weeks after irradiation is similar to the first six weeks, while damage to neural structureswithout significant improvement.Conclusion:In order to study its sciatic nerve function and structure changes in rats after exposureto ionizing radiation and discusse,the effects of different doses radiation on the surroundingnerves,we use the ionization of the experiment and the general state of the light microscopeby gross morphology, motility, neurology electrophysiological testing and histologicalexamination indicators.The results confirmed that rats receiving0.2Gy,1Gy,7Gy,14Gy and20Gy irradiation of different doses of ionizing radiation, are not significantly affected thegross features, but the impact on the sciatic nerve tissue morphology and ultrastructurediffer due to dose,which0.2Gy doses of ionizing radiation and1Gy after the structure ofthe sciatic nerve was unaffected, while accepting7Gy, after14Gy and20Gy dose ofradiation, ionizing radiation damage to the sciatic nerve began to appear, and withincreasing dose, this damage also increased, and further confirmed the ionizing radiation LNT theory limitations, as well as the knowledge "radiation effects have nonlinearcharacteristics in orthopedics and there is a critical point (threshold) exist in "... |
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