ENHANCED DEVELOPMENT OF MAMMARY-TUMORS IN RATS FOLLOWING TRANSPLACENTAL AND NEONATAL EXPOSURE TO ETHYLNITROSOUREA

  • 1 January 1978
    • journal article
    • research article
    • Vol. 38  (10) , 3182-3185
Abstract
Transplacental and neonatal induction of mammary tumors (MT) with ethylnitrosourea (ENU) was studied in Sprague-Dawley rats. A low transplacental ENU dose (10 mg/kg) did not increase the number of MT or shorten their latency period. High ENU doses (30 mg/kg neonatal, 60 mg/kg transplacental or 120 mg/kg transplacental) when corrected for differences in life span caused a significant shortening of the tumor induction period and an overall increase in tumor incidence. With high ENU doses, the MT were frequently multiple in the same animal and were more often malignant. Tumors developed in females. Only a few were observed in males. With a sufficient dose of carcinogen in susceptible animals, transplacental and neonatal ENU mammary carcinogenesis takes place. The experiment was originally designed to evaluate ENU-induced neurogenic tumors. The results on MT were obtained incidentally.