抄録
Various neoplasms were reported to have occurred in many organs of experimental animals treated with N-nitrosomethylurea (NMU) administered in drinking water, by gastric intubation or injected intraveously or intraportally. In the oral field, many investigators have reported that NMU induced odontogenic tumors or carcinomas of the oral cavity by such means. The authors tried to induce maxillofacial tumors in rats by injecting NMU intraarterially because this agent was known to have a topical carcinogenic activity and a considerably high incidence of tumor was found even with a single dose of NMU.
70mg/ kg of NMU as 2.5% physiological saline solution was singly injected into the left common carotid artery of 14 Sprague-Dawley rats (male 7, female 7) in the intraarterial injection (IA) group. While in the intravenous injection (IV) group, the same dose of NMU was injected into the left jugular vein of 8 rats (male 5, female 3).
After 8 months, an ameloblastic odontoma in the left mandible occurred in a female rat of IA group, while another one female rat in IA group developed a sarcoma in the left cheek about 9 months after treatment. Five female rats, 3 in IA group and 2 in IV group, developed mammary adenocarcinomas. Three male rats in IA group died in the early stage, however, the remaining male rats in both groups never showed any signs of neoplastic change.
These results mentioned above suggest the possibility that the administration of some carcinogenic agent by i. a. route may provide an experimental model intending to examine the tumorigenesis in various target organs, especially those located in the deep regions. However, a further study will be required in order to make this model more reliable.
