Prolonged opioid blockade with naltrexone and luteinizing hormone modifications in women with polycystic ovarian syndrome.
OBJECTIVE
To investigate whether enhanced LH levels of women with polycystic ovarian syndrome (PCOS) are the consequence of an absent hypothalamic opioid inhibitory control and/or an increased sensitivity of gonadotroph to GnRH, induced by sensitizing effects of circulating opioid peptides.


METHODS
Pulsatile LH secretion (10-minute sampling for 6 hours) and GnRH-stimulated (10 micrograms) LH release were investigated in 14 women with PCOS before and after the 5-day administration of placebo (n = 7) or the opioid antagonist naltrexone (50 mg/d; n = 7). Seven age- and weight-matched normal cycling women in follicular phase were used as controls.


RESULTS
In comparison with normal cycling women, PCOS showed normal frequency and increased amplitude LH pulses, elevated mean LH levels, and increased LH response to GnRH. In PCOS, placebo administration was not associated with any LH modification, whereas naltrexone enhanced the frequency and decreased the amplitude of LH pulses, without modifying mean LH levels and the LH response to GnRH.


CONCLUSIONS
The naltrexone-induced increment of LH frequency revealed a conserved central opioid tone in PCOS. Reduced LH pulse amplitude, induced by naltrexone, was not associated with a reduced LH response to GnRH or with a reduction in mean LH levels. Present data do not support a role for endogenous opioid peptides in the pathogenesis of increased LH levels in PCOS.
Istituto di Ginecologia Ostetricia e Fisiopatologia della Riproduzione Umana, University of Cagliari, Italy.
A
A
Cagnacci
R
R
Soldani
A M
AM
Paoletti
A
A
Falqui
G B
GB
Melis
D000328:Adult; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D006801:Humans; D007986:Luteinizing Hormone / Q000097:blood / Q000378:metabolism*; D009271:Naltrexone / Q000494:pharmacology*; D009292:Narcotic Antagonists / Q000494:pharmacology; D010919:Placebos; D011085:Polycystic Ovary Syndrome / Q000378:metabolism*; D012016:Reference Values; D013997:Time Factors
D009292:Narcotic Antagonists; D010919:Placebos; D007987:Gonadotropin-Releasing Hormone; D009271:Naltrexone; D007986:Luteinizing Hormone