Murray J C
Gray Laboratory, Mount Vernon Hospital, Northwood, Middlesex, U.K.
Scanning Microsc. 1994 Mar;8(1):79-85; discussion 85-7.
Fibrosis is a frequent complication of therapeutic radiation delivered to organ sites such as the thorax and pelvic region. We investigated the relationship between function, and biochemical and structural changes in the lung and colon of CBA mice irradiated with 240 kV X-rays. Progressive changes in lung function, as evidenced by increased breathing rates were observed out to 6 months post-irradiation. Biochemical studies demonstrated increased metabolism (synthesis and breakdown) of collagen around 6 months after irradiation, but provided no evidence of net collagen accumulation. Analysis of collagen isotypes revealed a slight increase in the ratio of types I and III. In the colons of irradiated mice, there was a progressive decrease in compliance out to 14 months post-irradiation. Collagen and total protein synthesis and breakdown rates were increased at early times, and returned to control levels by 4 months. No net accumulation of collagen was observed at any time. The ratio of collagen type I to III was increased at one year post-irradiation. We conclude that, in the CBA mouse, late functional changes after X-irradiation are not the result of a build-up of excessive connective tissue, although changes in collagen metabolism may occur relatively early on in the response to radiation.
纤维化是胸部和盆腔等器官部位接受放射治疗后常见的并发症。我们研究了用240 kV X射线照射的CBA小鼠肺和结肠的功能、生化及结构变化之间的关系。照射后6个月内观察到肺功能的渐进性变化，表现为呼吸频率增加。生化研究表明，照射后约6个月胶原代谢（合成和分解）增加，但没有证据表明胶原净积累。胶原同型分析显示I型和III型的比例略有增加。在照射小鼠的结肠中，照射后14个月内顺应性逐渐降低。早期胶原和总蛋白合成及分解率增加，到4个月时恢复到对照水平。在任何时候都未观察到胶原的净积累。照射后一年I型胶原与III型胶原的比例增加。我们得出结论，在CBA小鼠中，X射线照射后的晚期功能变化不是过量结缔组织积累的结果，尽管胶原代谢变化可能在辐射反应的相对早期就会发生。
