Horsman M R, Hansen P V, Overgaard J
Danish Cancer Society, Department of Experimental Clinical Oncology, Aarhus.
Int J Radiat Oncol Biol Phys. 1989 May;16(5):1273-6. doi: 10.1016/0360-3016(89)90297-6.
Nicotinamide induced radiosensitization of tumors has been suggested to be a consequence of a reduction in tumor hypoxia. We have investigated the possibility that nicotinamide may produce significant radiosensitization in a normal tissue in which the radiation response is also influenced by hypoxia. The normal tissue studied was testis and radiation damage was assessed by measuring survival of spermatogonial stem cells. The radiosensitizing action of nicotinamide in testis was compared to that observed in a C3H mammary carcinoma when assayed by both regrowth delay and local tumor control. Our results show that nicotinamide (1000 mg/kg; i.p.) enhanced radiation damage in both tissue types when the radiation was given up to at least 3 hr after drug injection. Enhancement ratios obtained when the drug and radiation were separated by a 1 hr time interval were between 1.1 to 1.2 for the testis and 1.0 to 1.5 for the tumor. The results suggest that nicotinamide will produce radiosensitization in testis, but the effect is small and less than that observed in tumors.
烟酰胺诱导肿瘤的放射增敏作用被认为是肿瘤缺氧减轻的结果。我们研究了烟酰胺在正常组织中产生显著放射增敏作用的可能性，在该正常组织中，辐射反应也受缺氧影响。所研究的正常组织是睾丸，通过测量精原干细胞的存活率来评估辐射损伤。当通过再生长延迟和局部肿瘤控制进行测定时，将烟酰胺在睾丸中的放射增敏作用与在C3H乳腺癌中观察到的作用进行比较。我们的结果表明，当在药物注射后至少3小时内给予辐射时，烟酰胺（1000mg/kg；腹腔注射）在两种组织类型中均增强了辐射损伤。当药物和辐射间隔1小时给予时，睾丸的增敏比在1.1至1.2之间，肿瘤的增敏比在1.0至1.5之间。结果表明，烟酰胺在睾丸中会产生放射增敏作用，但作用较小，且小于在肿瘤中观察到的作用。
