Estimation of oestrogenic activity in red clover (Trifolium pratense) using ovariectomized immature mice

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Abstract
Summary: Two experiments concerned with the testing of plant material for oestrogenic activity, utilizing vaginal reactions and uterine weight changes in immature ovariectomized mice are reported.In the first experiment the effects of varying the feeding period of an oestrogenic diet, containing 20% of freeze-dried red clover, and of varying the interval between the last feeding of this diet and slaughter were investigated. In general, uterine weight increased linearly with increased period of feeding and decreased linearly with delay in slaughtering. A feeding period of 4 days was satisfactory for comparisons based on uterine weight. If vaginal reactions were also to be utilized a feeding period of not less than 6 days was desirable.In the second experiment the dose-response relationships of diethylstilboestrol, genistein and oestrogenic red clover were investigated. All materials were incorporated in the diet of mice, and the level of plant material was kept at 20% of the mixed feed by adding inactive plant material where necessary. In general, either diethylstilboestrol or genistein could form a satisfactory standard for biological estimation of oestrogenic activity in red clover. Relative potencies based on uterine weight response and occurrence of vaginal opening and oestrus-type vaginal smears are given.