Prolonged opioid blockade with naltrexone and luteinizing hormone modifications in women with polycystic ovarian syndrome

Naltrexone effect on pulsatile GnRH therapy for ovulation induction in polycystic ovary syndrome: a pilot prospective study

The aim of the present study was to analyze the opioid influence on LH pulsatility in polycystic ovary syndrome (PCOS) patients and to evaluate the effectiveness of a long-term opioid antagonist (naltrexone) treatment in improving the pulsatile GnRH therapy which is successful in this syndrome. Ten obese women affected by PCOS participated in the study. Patients were hospitalized during the early follicular phase and underwent an oral glucose tolerance test (OGTT) with 75 g of glucose and a pulse pattern study followed by a GnRH test (100 pg i.v.). All patients were then treated for ovulation induction with pulsatile administration of GnRH (5 microg/bolus every 90 min). Since pregnancies did not occurr in any patient, after spontaneous or progestin-induced menstrual cycles, all patients received naltrexone at a dose of 50 mg/day orally for 8 weeks and during treatment repeated the basal protocol study and the ovulation induction cycle with the same modalities. The naltrexone treatment significantly reduced the insulin response to OGTT and the LH response to GnRH bolus, whereas it did not affect the FSH and LH pulsatility patterns. Concerning the ovulation induction by pulsatile GnRH, naltrexone treatment was able to improve, although not significantly, the ovulation rate (60% pre-treatment vs 90% post-treatment). Furthermore, the maximum diameter of the dominant follicle and the pre-ovulatory estradiol concentration were higher after long-term opioid blockade (follicular diameter 19.5+/-1.76 mm pre-treatment vs 21.6+/-2.19 mm post-treatment, p<0.001; maximum estradiol level 728.7+/-288.5 pmol/l pre-treatment vs 986.4+/-382.1 pmol/l post-treatment, p<0.05). During the naltrexone-pulsatile GnRH co-treatment two pregnancies occurred. In conclusion, our data show that naltrexone-pulsatile GnRH co-treatment is able to improve the ovarian responsiveness to ovulation induction in obese PCOS patients when compared to pulsatile GnRH alone. This action seems to be related to a decrease of insulin secretion. Further randomized studies should be performed in order to obtain significant conclusions on the possible clinical application.

Neuroendocrinology of the polycystic ovary syndrome

The clinical and biochemical heterogeneity of the PCOS is mirrored by the range of neuroendocrine disturbances described in women with PCOS. An increased serum LH concentration is a common, although not ubiquitous, feature and occurs primarily as a result of an increase in the amplitude of pulsatile LH, and presumably GnRH, secretion. The frequency of pulsatile GnRH secretion may, however, be increased in certain patients and may conceivably increase LH bioactivity by altering glycosylation of the molecule. Vigorous debate continues as to whether the observed changes in gonadotrophins are a primary abnormality or occur secondary to alterations in peripheral steroid concentrations. The proponents of the frequency hypothesis point to the discordant changes in gonadotrophin secretion that may be induced by rapid frequency exogenous GnRH stimulation in patients with hypogonadotrophic hypogonadism. Those who believe that the inappropriate gonadotrophin secretion is a secondary phenomenon argue that manipulation of peripheral steroid levels, by either administration of oestrogen/progesterone, induced ovulation or ovarian diathermy, may correct the disturbance of gonadotrophin secretion, which is therefore presumably a consequence of changes in ovarian steroid feedback signals. The weight of evidence at present suggests that the inappropriate gonadotrophin secretion is usually a secondary abnormality, although there may be groups of patients with a primary increase in GnRH pulsatility. The search for a unifying neuroendocrine disturbance in PCOS has been frustrated by the inability to find consistent evidence of disordered central dopaminergic, opioidergic, noradrenergic or serotoninergic pathways. Those abnormalities which have been uncovered appear to be secondary to chronic anovulation rather than of primary pathological import, and emphasize the central importance of the ovary as culprit rather than victim in PCOS.

Evidence that an altered prolactin release is consequent to abnormal ovarian activity in polycystic ovary syndrome

OBJECTIVE

To investigate whether endogenous dopaminergic activity is impaired in polycystic ovary syndrome (PCOS)-affected women and is normalized by medical ovariectomy.

PATIENTS

Women with PCOS untreated (n = 23) and treated for 3 months with GnRH analogue (GnRH-a) administration (n = 10) and normal cycling young women (n = 23) as controls.

INTERVENTIONS

Acute blockade of dopaminergic receptors by the IV administration of 5 mg of the dopaminergic receptor blocking agent sulpiride (sulpiride test) was performed 3 to 7 days after the initiation of spontaneous menses in cycling women or medroxyprogesterone acetate-induced menses in PCOS women. In PCOS women treated with GnRH-a administration (goserelin depot, 3.6 mg SC every 28 days), the sulpiride test was repeated 10 to 15 days after the third GnRH-a administration.

MAIN OUTCOME MEASURE

Basal PRL levels and PRL increase induced by sulpiride.

RESULTS

Basal PRL levels and the PRL response to sulpiride were increased in women with PCOS. In women with PCOS medical ovariectomy induced by GnRH-a administration reversed to normal both basal and sulpiride-stimulated PRL levels.

CONCLUSIONS

In women with PCOS the abnormal regulation of PRL and presumably of hypothalamic neurotransmitters controlling PRL secretion is not a primary alteration but it is likely dependent on abnormal ovarian functionality.