抄録
Effects of estradiol on hypophyseal secretion of FSH and LH were studied in parabiotic unions of hypophysectomized-ovariectomized rat and ovariectomized rat, both bearing intrasplenic ovarian grafts. Twenty-five daily subcutaneous injections of 0.5μg to ovariectomized parabionts or of 10.0μg to hypophysectomized-ovariectomized members could hardly depress the hypersecretion of gonadotrophins by the hypophysis of ovariectomized rats, both follicular growth and luteinization taking place in intrasplenic ovarian grafts in hypophysectomized as well as hypophysis-intact parabionts. In contrast, 25 daily injections of 1.0μg to ovariectomized parabionts or of 20.0μg to hypophysectomized-ovariectomized parabionts so decreased the secretion of gonadotrophins, LH in particular, that follicular growth was not accompanied by luteinization in grafts of hypophysectomized members although both follicular growth and luteinization might occur in grafts in hypophysis-intact partners. If daily dose given to ovariectomized parabionts was increased to 5.0μg, luteinization seldom occurred in grafts in the recipients and even follicular growth was inhibited in those in their hypophysectomized partners. On the basis of these results, role of estrogen in the regulatory mechanism of the secretion of gonadotrophins in parabiotic rats was discussed.
