Effects of clomiphene citrate on episodic luteinizing hormone secretion throughout the menstrual cycle

Abstract

Pituitary luteinizing hormone secretory dynamics (pulse frequency and amplitude) were evaluated in eight normal women administered clomiphene citrate or placebo. After 5 days of treatment clomiphene citrate was found to increase mean luteinizing hormone secretion by increasing the amount of pituitary luteinizing hormone released per pulse. No change in pituitary luteinizing hormone interpulse interval was found in the follicular phase of the cycle, although a faster pulse frequency in the luteal phase was found after clomiphene citrate when compared with placebo. No differences were found in the luteal phase (pulse frequency, amplitude, and mean luteinizing hormone level) after clomiphene citrate versus placebo in the volunteers. These data suggest that the principal mechanism of action of clomiphene citrate is an increase in the concentration of hypothalamic gonadotropin releasing hormone into the hypothalamic-pituitary portal circulation, with a resultant increase in pituitary luteinizing hormone secretion.