Kamei T, Kohno T, Ohwada H, Takeuchi Y, Hayashi Y, Fukuma S
Division of Pathology, School of Medicine, Chiba University, Japan.
Cancer. 1993 Apr 15;71(8):2477-83. doi: 10.1002/1097-0142(19930415)71:8<2477::aid-cncr2820710809>3.0.co;2-g.
Vitamin deficiency may be related to carcinogenesis. Cytologic examinations of sputum have already found that the administration of folate and vitamin B12 suppressed the development of squamous metaplasia and atypia in smokers' airways. The authors investigated the effect of folic acid, vitamin B12, and vitamin A on the formation of metaplasia and hyperplasia in methylcholanthrene (MCA)-treated rats.
The SD strain of rats received 10 mg of MCA intratracheally and was divided into six groups as follows: (1) vitamin A; (2) folic acid; (3) vitamin B12; (4) vitamin B12 with folic acid; (5) a combination of vitamin A, folic acid, and vitamin B12; and (6) no vitamins. The Lower respiratory tract epithelia of the rats were examined histologically 20, 32, and 36 weeks after MCA administration and at the end of the experiment.
A clear difference was detected between the group receiving folic acid and that receiving vitamin A. In the former group, metaplasia was found in only one rat, atypia was not found, and hyperplasia with marked changes was present in less than 50% of other groups. In the latter group, atypia was found in all of the metaplastic foci.
It was suggested that the epithelial hyperplasia and metaplasia of respiratory tract induced by MCA can be suppressed by the administration of folic acid.
维生素缺乏可能与致癌作用有关。痰液的细胞学检查已经发现，给予叶酸和维生素B12可抑制吸烟者气道鳞状化生和异型增生的发展。作者研究了叶酸、维生素B12和维生素A对甲基胆蒽（MCA）处理的大鼠化生和增生形成的影响。
SD品系大鼠经气管内给予10mg MCA，并分为以下六组：（1）维生素A组；（2）叶酸组；（3）维生素B12组；（4）维生素B12与叶酸联合组；（5）维生素A、叶酸和维生素B12联合组；（6）不补充维生素组。在给予MCA后20、32和36周以及实验结束时，对大鼠的下呼吸道上皮进行组织学检查。
叶酸组和维生素A组之间检测到明显差异。在前一组中，仅在一只大鼠中发现化生，未发现异型增生，其他组中不到50%出现伴有明显变化的增生。在后一组中，在所有化生灶中均发现异型增生。
提示给予叶酸可抑制MCA诱导的大鼠呼吸道上皮增生和化生。
