Short Communication HORMONAL STATUS AND TESTOSTERONE METABOLISM OF DMBA-INDUCED RAT MAMMARY CARCINOMAS

metabolism in rat mammary carcinomas is the reduction of testosterone to 5a dihydrotestosterone and 5a androstanediol (King, Gordon and Helfenstein, 1964; Miller, Forrest and Hamilton, 1974). In vitro addition of oestradiol 17/? to incu-bations of hormone-dependent rat mammary carcinomas is associated with an inhibition of 5a reduction of testo-sterone (Miller, 1976a). The aim of the present study was to determine if in vivo hormone manipulation was associated with similar changes. A single i.v. injection of 5 mg 7-12-dimethylbenzanthracene (DMBA) was given to 24 randomly bred female Sprague Dawley rats at 50 days of age. The size of the tumours which were induced was monitored twice weekly by measuring with calipers 2 diameters at right angles. When the tumours were 2 x 2 cm in size, animals were allocated to one of 3 groups. Those in Group I were killed without further treatment, those in Group II were oophorectomized and killed 14 days later and those in Group III were oophorectomized but 14 days later re-ceived daily s.c. injections of 1 jug oestra-diol in corn oil for a further 14 days, when they were killed. In all animals, oophorectomy led to regression oftumours; all those subsequently given oestradiol showed regrowth. Tumours were harvested at death and treated at 0°C. Each was finely sliced in Krebs Ringer phosphate buffer pH 7-4 (10 ml/g tumour) and an NADPH-generating system (200,umol glucose-6