Interactions between phyto-oestrogens and steroids in the cervical mucus and uterine weight responses in ewes

Abstract

Cervical mucus and uterine weight responses were measured in ovariectomized ewes grazing pastures containing isoflavones and coumestans—red clover (Trifolium pyatense) and lucerne (Medicago sativa) respectively. The red clover pastures were highly oestrogenic to the ewes, large productions of mucus and high uterine weights being recorded. Grazing of these pastures for a 12-day period prior to bioassay had no significant effect on either response. The lucerne pastures were only mildly oestrogenic.

Administration of progesterone either by subcutaneous implant (375 mg progesterone) or intramuscular injection (10 mg per ewe per day) inhibited the mucus responses to isoflavones but did not decrease the uterine weight responses. In one of two experiments, the uterine weight was unaffected and in the other experiment the weight was enhanced by progesterone treatment. Testosterone propionate injections (10 mg per ewe per day) had no effect on either the cervical mucus or uterine weight responses, but induced oestrus in all ewes.