The effects of various hormones and immunopotentiators on 7, 12-dimethylbenz (a) anthracene (DMBA)-induced carcinogenesis in the SD rat mammary glands were studied. Female SD rats aged six weeks were given 20 mg of DMBA by gastric intubation.
A week after the DMBA administration, these rats were divided into six groups : tamoxifen (TAM) (0.4mg/kg/day, PS), medroxyprogesterone acetate (MPA) (10mg/kg/day, IM), oophorectomy (Ovex) (a week after DMBA administration), OK-432 (0.1K· E/kg/week, IP), PSK (60mg/kg/day, PS) and the control group. Each group had been administered the respective drug between first and 12th weeks, and the presence of mammary tumors had been investigated every week up to the 15th week. Mammary tumors in the control group appeared only between the sixth and 12th weeks.
The period of administration in the therapeutic groups agreed with that of the appearance of mammary tumors in the control.
The occurrence of mammary tumors at the 12th and 15th weeks in each group was 94.5% in control, 60.9% and 82.6% in PSK, 69.6% and 73.9% in OK-432, 18.2% and 36, 4% in TAM, 0% in Ovex and 0% in MPA.
The first appearance periods of DMBA tumors were 7.9±1.7 weeks in control, 8.5±1.7 weeks in OK-432, 9.6±2.7 weeks in PSK and 12.1±2.9 weeks in TAM.
Compared with the control group, those receiving hormones and immunopotentiators showed a significantly lower rate in the appearance of DMBA tumors and a delay in the first appearance period of DMBA tumors.
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