Effect of an increase in FSH on the production of gonadotrophin-surge-attenuating factor in women

Abstract

Gonadotrophin-surge-attenuating factor (GnSAF) is a putative nonsteroidal ovarian factor that is produced by FSH and that attenuates the LH surge in superovulated women. To study further the role of FSH in the production of GnSAF, 12 normally ovulating women were divided into two groups and investigated during two cycles: a cycle treated with placebo (control) and a cycle treated with FSH. In group 1 (n = 6), placebo (2 ml 0.9% normal saline) or FSH (450 iu) was injected i.m. on day 2 of the cycle (09:00 h). In group 2 (n = 6), placebo (2 ml 0.9% normal saline) or FSH (225 iu) was injected on the day (09:00 h) on which the dominant follicle was 14-15 mm in diameter, as measured by ultrasound (i.e. after the pituitary had been primed by endogenous oestrogen for several days). The response of LH over 30 min (delta LH) to an injection of 10 micrograms LHRH i.v. (bioassay for GnSAF in vivo) was investigated once a day in group 1, and 4, 8, 12 and 24 h after the injection of placebo or FSH in group 2. In group 1, delta LH was significantly attenuated 12 h after treatment with FSH compared with the control cycles, while serum oestradiol concentrations increased 24 h after the injection of FSH. The decrease in delta LH lasted for the period when the FSH concentration was increased (3 days). A significant decrease in the basal concentration of LH was correlated with the increase in the oestradiol concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Attenuin: What It Is, How It Works and What It Does

“…This effect was seen as early as 8 h after FSH administration, although circulating estradiol did not increase significantly until at least 24 h after gonadotropin administration. Subsequently, this group also concluded that attenuin bioactivity in FSHtreated women could not be due to an increase in circulating total -inhibin (Messinis et al, 1991(Messinis et al, , 1993(Messinis et al, , 1994(Messinis et al, , 1996. Attenuin bioactivity has so far been found in serum, FF and ovarian extracts from superovulated (Fowler et al, 1994a) and cyclic women , in bFF (Van Dieten et al, 1999), in porcine FF (pFF; Danforth et al, 1987;Kita et al, 1994), in rat ovarian extracts (de Koning et al, 1989) and in rat testicular extracts (Tio et al, 1994).…”

Future use of clomiphene in ovarian stimulation. Clomiphene in the 21st century

“…When clomiphene is given to women for 5 days during the early follicular phase of the cycle, it stimulates not only the secretion of FSH, but also of LH and this may result in relatively high LH concentrations during the late follicular phase (Messinis et al, 1986b), which may adversely affect the outcome of pregnancy (Stanger and Yovich, 1985). The combination of clomiphene with human gonadotrophins may suppress basal LH levels in late follicular phase more than clomiphene, but even then LH levels are still higher than with gonadotrophins alone, when serum LH values decline significantly within the first 24 h from the onset of treatment (Messinis et al, 1986b;Messinis et al, 1994). A theoretical approach to the use of clomiphene for ovulation induction would be to combine it with a GnRH antagonist in order to reduce LH values during the late follicular phase.…”

Ovarian control of pituitary sensitivity of luteinizing hormone secretion to gonadotropin-releasing hormone in women with the polycystic ovary syndrome

“…It is known that the ovaries, in addition to the steroids, secrete nonsteroidal substances, the activity of which becomes particularly evident under conditions of ovarian stimulation by exogenous FSH (5). Such a dynamic approach has been previously applied to normal women and has provided important information regarding the ovarian control of gonadotropin secretion (6,7).…”

“…The women with PCOS had a body mass index (BMI) of 26 AE 2.5 kg/m 2 and the controls of 21 AE 1.1 kg/m 2 . All women participated in the same experimental procedure (Exp) including the SC injection of a single dose 450 IU recombinant FSH (Puregon 150 IU; Organon, Hellas, Greece) based on our previous studies (6,7,9). The day of the FSH injection was designated as day 1 (9 AM).…”