Relationship between follicle size and gonadotrophin surge attenuating factor (GnSAF) bioactivity during spontaneous cycles in women

P. A. Fowler
2001 Human Reproduction  
BACKGROUND: We have previously demonstrated that follicles ≤11 mm diameter from women undergoing IVF contain higher concentrations of gonadotrophin surge attenuating factor (GnSAF) bioactivity than large follicles from the same ovaries. METHODS: To determine whether this finding is relevant to spontaneous cycles, follicular fluid aspirated from 37 follicles between 3 and 25 mm in diameter from 14 pairs of ovaries from regularly cycling women undergoing total abdominal hysterectomy and bilateral
more » ... ctomy and bilateral salpingoophorectomy for benign gynaecological disease was pooled into size categories (3 ⍣ 4, 5 ⍣ 6, 7 ⍣ 8, 9 ⍣ 10, 11 ⍣ 12, 14 ⍣ 15, 18 and 25 mm). These pools were bioassayed for GnSAF and inhibin-A, inhibin-B and activin-A concentrations were determined. RESULTS: Follicles of 5 ⍣ 6 mm diameter contained the highest concentrations of GnSAF bioactivity (reducing GnRH-induced LH secretion to 38 ⍨ 8% of control, P < 0.001), while those of 25 mm diameter contained one quarter of this concentration (reducing GnRH-induced LH secretion to 72 ⍨ 2% of control, P < 0.05). GnSAF bioactivity was closely related to follicle size (r ⍧ -0.836, P < 0.01), but not to inhibin-A, inhibin-B or activin-A concentrations. CONCLUSIONS: The finding that small follicles contain high concentrations of GnSAF bioactivity, which fall as folliculogenesis progresses during spontaneous cycles, support the hypothesis that GnSAF has a role in preventing the premature onset of the LH surge in women.
doi:10.1093/humrep/16.7.1353 pmid:11425812 fatcat:lqqksaphq5awlk3bwsmgojw4zi