PULSATILE GONADOTROPIN-SECRETION IN WOMEN WITH POLYCYSTIC-OVARY-SYNDROME AFTER GONADOTROPIN-RELEASING-HORMONE AGONIST TREATMENT

In polycystic ovary syndrome (PCOS), increased luteinizing hormone (LH ) pulse frequency has been attributed to either the hypothalamic gonad otrophin-releasing hormone (GnRH) pulse generator or ovarian oestrogen feedback, To address this issue, a detailed examination of pulsatile LH secretion was undertaken during recovery from GnRH agonist (GnRHa) suppression, Each of six women with PCOS and six normal ovulatory wome n received daily GnRHa treatment for 14 weeks, Frequent blood samples were collected and assayed for gonadotrophins, androgens and oestrogen s before, during and up to 4 weeks after treatment, Women with PCOS ha d higher basal LH pulse frequency and amplitude and increased serum co ncentrations of LH, androstenedione, testosterone and oestrone than co ntrols, After 3 months of GnRHa treatment, all these parameters were s uppressed with no differences observed between the two groups, One wee k after cessation of GnRHa, LH pulse frequency promptly returned to pr etreatment range with no between-group differences noted, whereas LH p ulse amplitude, serum gonadotrophins and ovarian steroids remained max imally suppressed and equivalent in the two groups, Subsequent LH puls e frequency remained constant while LH pulse amplitude and circulating concentrations gradually increased in parallel with a return of serum oestrogen to pre-treatment values, Despite comparable resumption of L H secretion in the two groups, corresponding androgen concentrations i n women with PCOS were greater than those of normal ovulatory women, T hus, the immediate restoration of LH pulse frequency after discontinui ng GnRHa treatment is largely independent of ovarian oestrogen product ion and reflects primacy of the GnRH pulse generator in determining ba sal LH pulse frequency, Equivalent LH pulse frequency rates in the two groups during the recovery period do not suggest an intrinsic hypotha lamic-pituitary hyperactivity in PCOS.