LHRH analogues can be luteotrophic

Seven normally menstruating women were treated with consecutive daily supraoptimal doses of the LHRH analogue Hoe 766 initiated in the mid/late luteal phase. This treatment caused immediate increases in circulating levels of LH, FSH, oestradiol (E2) and progesterone. After a few days, the pituitary became unresponsive to Hoe 766 and LH and FSH levels returned to the normal luteal phase ranges while progesterone and E2 levels did not decline to their respective pre-treatment levels until at least 24 h later. As a result of this treatment, the onset of the next menses was delayed in five of the seven women, indicating luteotrophism. These data show that the corpus luteum was responsive to increased LH/FSH during Hoe 766 therapy. Therefore, reported luteolytic effects of short-term treatment with LHRH and/or its analogues were probably not caused by direct inhibitory ovarian action but by reduction of ensuing pituitary gonadotrophin levels.