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目的 观察幼年猪下丘脑区接受不同剂量单次照射后下丘脑—垂体—睾丸轴反应。方法 (1)20 只幼年雄性小型猪分为5 个组,每组4 只,以蝶鞍上1 cm 为靶点等中心、10 MV 的X 射线、=16 m m 限光筒平行对穿照射,靶区中心吸收剂量分别为5 ,10,15 ,20 Gy;(2) 猪血清睾丸酮测定:照射后每隔4 周采血1 次直至照射后36 周,采用放射免疫分析方法测定猪血清睾丸酮水平;(3)将观察期满40 周的动物处死,取下丘脑组织行电镜和光镜观察,睾丸组织行光镜观察。结果 (1)照射后20 周,15,20 Gy 组动物体重出现降低趋势。(2)5 Gy 组血清睾丸酮水平在照射后曾有一过性降低,于照射后28 周与对照组基本相似;10 Gy 组略低于对照组;15,20 Gy 组持续呈低水平。(3) 光镜观察见下丘脑组织基本正常;电镜观察见10,15 ,20 Gy 组神经细胞浆水肿,髓鞘肿胀、内膜向轴索内突出,血管内皮细胞和胶质细胞增生;光镜下见精原细胞和间质细胞数量减少,细胞体积明显缩小,以20 Gy 组为最明显。结论 幼年猪下丘脑区接受5 Gy 的单次剂量照射就可以发生促性腺激素释放素神经细胞分泌功能的抑制,认为幼年猪的下丘脑区属放射敏感组织;10 Gy 以上单次照射可以导致明显神经内分泌障碍
Objective To observe the hypothalamus-pituitary-testicular axis response of young pigs in hypothalamus area under different doses of single irradiation. Methods (1) Twenty young male minipigs were divided into five groups with 4 rats in each group. The center of the sella was 1 cm, the center of the septum was 10 cm X-ray, , Respectively, and the absorbed dose in the center of the target area was 5, 10, 15 and 20 Gy, respectively. (2) Porcine serum testosterone assay: Pig blood serum testosterone levels were measured by radioimmunoassay after blood was taken every 4 weeks and irradiated for 36 weeks ; (3) The animals at the expiration of 40 weeks were sacrificed, and the hypothalamus was removed under electron microscope and light microscope. The testis was observed under light microscope. Results (1) At 20 weeks after irradiation, body weight of 15,20 Gy group decreased. (2) The level of serum testosterone in 5 Gy group had a transient decrease after irradiation, which was similar to the control group at 28 weeks after irradiation; the level was lower in 10 Gy group than in control group; (3) Hypothalamus tissue was found to be basically normal by light microscopy. Neuronal cell edema, myelin sheath swelling, endoplasmic axial protrusion, vascular endothelial cells and glial cell hyperplasia were observed in 10,15,20 Gy group. Light Microscopically, the number of spermatogonia and interstitial cells decreased and the volume of cells decreased significantly. The most obvious was the 20 Gy group. Conclusions The hypothalamus area of young pigs can inhibit the secretion of gonadotrophin-releasing neurons when exposed to a single dose of 5 Gy. The hypothalamus in young pigs is a radiosensitive tissue. Single irradiation above 10 Gy can lead to significant Neuroendocrine disorders