© 1995 Oxford University Press
research-article |
Phenobarbital promotes the development of adenocarcinomas in the accessory sex glands of MNU-inoculated L-W rats
Labund Laboratory, University of Notre Dame Notre Dame, IN 46556, USA
Aged Lobund-Wistar (L-W) rats develop: (i) spontaneous and induced metastasizing adenocarcinomas in the prostate and seminal vesicle (P-SV) complex; and (ii) spontaneous hepatomas and hepatocarcinoinas. Within the time-frame of 14 months, similar adenocarcinomas were induced in the P-SV complex in 7090% of younger L-W rats by a single i.v. inoculation of methylmtrosourea (MNU) which was followed by slow release s.c. implants of testosterone proplonate (TP). Within the same time-frame, neither MNU nor TP alone induced signillcant incidences of P-SV tumors; and untreated control L-W rats were disease-free. Methylnitrosoarea or TP and combinations thereof did not induce liver tumors. However, when MNU-inoculated L-W rats were fed phenobarbital (PB), they developed (i) metastasizing adenocarcinomas in the P-SV complex and (ii) altered cellular foci and nodules in the livers. Methylnitrosourea induced a high incidence of benign lung adenomas which progressed to lung cancers in numbers which were of marginal significance. Thus, dormant MNU-initiated cells in the P-SV complex were activated by phenobarbital, to produce adenocarcinomas in that complex.