Pituitary–ovarian axis during lactational amenorrhoea. II. Longitudinal assessment of serum FSH polymorphism before and after recovery of menstrual cycles

BACKGROUND: The association of normal serum levels of immunoassayable gonadotrophins with anovulation during lactational amenorrhoea (LA) has not been fully explained. METHODS: Serum FSH polymorphism was analysed in 10 women during LA between days 60 and 70 post-partum and again, in the mid-follicul...

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Bibliographic Details
Published in:Human reproduction (Oxford) 2006-04, Vol.21 (4), p.916-923
Main Authors: Velasquez, E.V., Creus, S., Trigo, R.V., Cigorraga, S.B., Pellizzari, E.H., Croxatto, H.B., Campo, S.
Format: Article
Language:English
Subjects:
Amenorrhea - blood
amenorrhoea
anovulation
Biological and medical sciences
breastfeeding
Chromatography
Female
Follicle Stimulating Hormone - blood
follicular growth
FSH polymorphism
Gynecology. Andrology. Obstetrics
Humans
Lactation - blood
Longitudinal Studies
Medical sciences
Menstrual Cycle - blood
Ovarian Follicle - growth & development
Pituitary Gland - physiology
Postpartum Period - blood
Protein Isoforms - blood
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Summary:BACKGROUND: The association of normal serum levels of immunoassayable gonadotrophins with anovulation during lactational amenorrhoea (LA) has not been fully explained. METHODS: Serum FSH polymorphism was analysed in 10 women during LA between days 60 and 70 post-partum and again, in the mid-follicular phase (MFP), after resuming menstrual cyclicity. FSH microheterogeneity was characterized according to charge, using preparative isoelectric focusing, and according to the inner structure of carbohydrate chains, using lectin chromatography. RESULTS: A significantly higher proportion of FSH charge isoforms isolated below pH 4.10 and a lower proportion of FSH isoforms bearing highly branched oligosaccharides were observed during LA when compared to MFP. Further analysis with higher resolution showed that FSH charge isoforms, isolated in the lower pH range in LA, corresponded to FSH molecules bearing highly branched and biantennary oligosaccharides. FSH isoforms bearing hybrid-type oligosaccharides were only present during LA. The circulating FSH isoform mix was significantly less bioactive in LA than in MFP. LA is characterized by a more acidic mix of FSH isoforms, containing hormone bearing less processed oligosaccharides, with decreased biopotency in comparison with the follicular phase. CONCLUSIONS: This FSH microheterogeneity may be one of the critical factors contributing to incomplete follicular development and anovulation during LA.
ISSN:0268-1161
1460-2350
DOI:10.1093/humrep/dei411