Effect Of Different Dose Radiation On Nasal Mucosa And Changes Of IL-1, IL-6, TNF-Α In The Serum Of The Guinea Pig

Objective: To study histopathologic changes in nasal mucosa and concentration of IL-1, IL-6 , TNF-αin serum of guinea pigs following different dose irradiation. Methods: 125 healthy guinea pigs were divided into the control group and four irradiation groups randomly, 25 guinea pigs for each group. The animals of control group were exposed to fake X-rays, while the animals of the four irradiation groups were exposed nasally to linear accelerator X-rays once a week for three weeks. The total dose of irradiation was 9Gy, 15Gy, 21Gy and 30Gy respectively. 5 animals per one group were sacrificed randomly at 1 week, 1, 2, 3, 4 month after irradiation, the histopathologic changes of nasal mucosa were observed under optical, scanning electron and transmission electron microscope. At the same time, blood were drawn from the heart and the concentration of IL-1, IL-6 and TNF-αin the serum were measured by ELISA. Results: (1) Exposure to irradiation resulted in the guinea pig's loss of appetite, the exposed skin's congestion and depilation one week after irradiation. The changes were more serious in the larger dose irradiation groups. No animal death occurred when irradiation dose was less than 15Gy, but, several deaths occurred when 21Gy, and the death rate amounted to 60 percent within two weeks when 30Gy. (2) 9Gy nasal irradiation could only lead to slight destruction of epithelia, such as degeneration of epithlia, inflammatory cells infiltration of the subepithelia region, but the array of them was not inordinate. Under transmission electron microscope, mild degeneration could also be found in some epithelial cells, such as cytoplasm deformity, but cell membrane and nuclei were integral, the array of them was not inordinate. Under scanning electron microscope, the nasal mucosa were integral, epithelia detachment could seldom be found. Goblet hyperplasia could be found in some area, while the number of cilia decreased. After one month, epithelial cells repaired step by step, and restored to normal in three months. 15Gy nasal irradiation caused the more serious destruction, such as epithelial cells necrosis and detachment, more inflammatory cells infiltration of the subepithlia, goblet hyperplasia in the nasal mucosa. The array of submucosa glands was inordinate. Under transmission electron microscope, epithelial cells degeneration, necrosis and detachment could be found and the array of the remain epithelial cells was inordinate, intercellular spaces were widened. Part of the cell membrane was dissolved, and the cytoplasm was deformed. Some cilia disappeared. Under scanning electron microscope, epithelial cells detachment could also be found in some areas. The array of cilia was inordinate, orientation was different and inverse. After one month, the nasal mucosa repaired step by step, but part of the area was squamous epithelia instead of the normal ciliary structure. The greater the dose, the more serious the damage, When reached 21Gy, most epithelial cells necrosis and detachment could be observed. The number of basal cells decreased, and intercellular spaces were widened much. Most cells cytoplasm were deformed and homogenized, and nuclei were collapsed. The cilia were adherenced together and were in great disorder. After one month, a few epithelial cells restored to normal, most part of the area was replaced by squamous epithelium. When dose increased to 30Gy, most epithelial cells were detached, the remains were homogenized, degeneration or necrosis was also observed in some basal cells. Mucus degeneration could be seen in some submucosa glands. After one month, degeneration or necrosis was still observed in some epithelial cells, inflammatory cells infiltrating in the submucosa. Fibrous connective tissue hyperplasia could be seen in the basilar part of nasal mucosa. (3) Irradiation caused an apparent increase of IL-1, maintaining a high level. When dose of irradiation was under 15Gy, IL-6 and TNF-αincreased and kept in high level. The extent of increase was foundsignificantly correlated with the dose of irradiation. However, when dose exceeded 15Gy, no significant increase or even decrease of IL-6 and TNF-αwas found. Conclusion: 1,The adult guinea pig weighing about 300 gram could tolerate irradiation under 15Gy, but when dose reached 21Gy, some animals died due to exposure, when more than 30Gy, more than half animals died within one month after exposure. 2,Irradiation could result in acute inflammatory reaction, including the nasal mucosa congestion and edema, epithelial cells degeneration, necrosis or shedding, inflammation cells infiltrating in the submucosa, submucosa glands were damaged. And the greater the dose, the more severe the damage. Then epithelial cells repaired step by step, but part of the area was replaced by squamous epithelium instead of the normal ciliary structure. The larger the dose, the lower the cilia cover rate, the more severe the submucosa glands damage. 3,After exposure to certain dose of irradiation, IL-1,IL-6 ,TNF-αincreased and maintained in high level for long time. It resulted in the irradiation tissue's continuing inflammatory reaction and in turn caused damage of the tissue that was more difficult to recover. It may contribute to the pathogenesis of irradiation injuries.