Effects of carcinogen and/or mutagen on normal and gonadotropin-primed ovaries of mice

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Abstract
The influence of pregnant mare serum gonadotropin (PMSG) on the induction of ovarian tumors by carcinogen (DMBA) and/or mutagens (EMS and BMS) has been studied in Swiss albino mice. Priming of the ovaries of 6-week-old mice with PMSG (50 lU/mouse) 24 h before intragastric intubation of DMBA (5 mg/mouse) resulted in a significant increase in ovarian tumors when harvested 6 months after the treatment. A similar experiment done on 8-week-old mice yielded confirmatory results. Mutagens (EMS and BMS) failed, at given dose levels (200 mg/kg and 300 mg/kg body weight), to induce tumors in normal as well as PMSG-primed ovaries. Nor could these mutagens enhance DMBA-induced tumor incidences in normal or PMSG-primed ovaries. Pretreatment of animals with PMSG-enhanced DMBA-induced oocyte depletion and also increased the DMBA-3H activity in the ovaries. The augmentation of DMBA-induced tumors in PMSG-primed ovaries could be due to increased uptake of DMBA and increased depletion of oocytes. It is also possible that PMSG-primed ovaries provided more proliferating granulosa cells (and macromolecules) for the interaction of DMBA (or its metabolites) and thereby increased the chances of cell transformation in the ovaries.