Plasma and pituitary gonadotropins and prolactin after hysterectomy and treatment with uterine extracts in female rats. A kinetic study.

The kinetic of changes in plasma concentrations and pituitary contents of FSH, LH, prolactin after hysterectomy and treatment with steroid-free uterine extracts were studied in adult, non-pregnant female rats. The post-castration rise of plasma and pituitary FSH and plasma LH was inhibited but the plasma prolactin was elevated by hysterectomy. Steroid-free uterine extracts from previously castrated animals increased the plasma FSH, LH and prolactin concentrations in hysterectomized females 48 hours after administration. Uterine extracts from intact and oestradiol-substituted-castrated animals decreased the pituitary prolactin content 48 h after single i.p. injection. Pituitary FSH and LH contents were not affected by single dose of uterine extracts at any time which were examined. It is concluded that the uterus may play some role in the synthesis and release of pituitary gonadotropins and prolactin.