THE HYPOTHALAMIC-PITUITARY-LUTEAL AXIS IN WOMEN - EFFECTS OF LONG-TERM ORALLY-ACTIVE OPIOID ANTAGONIST (NALTREXONE) ADMINISTRATION

Aim of our study is to assess the effect of a long-term oral opiate an tagonist treatment during the luteal phase on the hypothalamic-pituita ry-ovarian axis. Fourteen normovulatory women partecipated to the stud y. Immediately after the ovulation, the patients were randomly divided in two groups: in the first one women received naltrexone 50 mg/die o rally (Antaxone Zambon Italy) from day 1 of the luteal phase for 7 day s. In the second patients were treated with placebo for the same perio d and served as control group, On day 7, patients were hospitalized fo r a pulse pattern study followed by a GnRH test, LH, FSH, Estradiol, P rogesterone were assayed, The naltrexone administration strongly incre ased the number as well as the amplitude of the gonadotropin pulses, T he circulating P levels were also significantly higher in treated pati ents. The GnRH injection significantly increases the gonadotropin secr etion in all patients. The stimulated LH and FSH secretion was signifi cantly greater in treated patients when compared to controls. Such dis charge of LH determined a significant increase of progesterone product ion in controls, but failed to stimulate the corpus luteum in treated patients, In conclusion the present paper strengtheen an important rol e of the opioidergic system in the regulation of GnRH pulsatility in l uteal phase, Moreover, our findings confirms the sensibility of the co rpus luteum to LH and the possibility to stimulate the P secretion dur ing the luteal phase. (C) 1997, Editrice Kurtis.