title: Dynamic changes in glycosylation and glycan composition of serum FSH and LH during natural ovarian stimulation.
abstract: BACKGROUND
  Glycosylation and glycan composition are of fundamental importance for the biological properties of FSH and LH. The aim of this study was to determine the glycosylation, sialylation, and sulfonation of serum FSH and LH throughout the normal menstrual cycle.
  
  
  METHODS
  Serum samples were collected from 79 healthy women with regular menstrual cycles. The mean numbers of anionic monosaccharide (AMS), sialic acid (SA), and sulfonated N-acetylgalactosamine (SU) residues per FSH and LH molecule were estimated for all sera with methods based on electrophoreses, neuraminidase treatments, and fluoroimmunoassays of the gonadotrophins.
  
  
  RESULTS
  Di-glycosylated glycoforms (FSHdi, LHdi) were detected in serum in addition to tetra-glycosylated FSH (FSHtetra) and tri-glycosylated LH (LHtri). FSHdi exhibited two peaks: one on day 5 to 7 and one, more pronounced, at midcycle. FSHtetra plateaued at a high concentration from day 5 to 15, without a midcycle peak. There were lower concentrations of LHdi than LHtri, except at midcycle when the opposite occurred. The mean numbers of SA and SU residues per molecule of FSH and LH in serum showed four different patterns during the cycle, all with highly significant (P < 0.0001) differences between levels at different phases of the cycle. The pattern of SA residues on FSH was 'M'-shaped, and that of SU on LH 'V'-shaped.
  
  
  CONCLUSIONS
  Serum FSH and LH governing the natural ovarian stimulation process exhibited dynamic changes of glycosylation and glycan composition. This new information on the FSH and LH molecular structures may lead to more successful mono-ovulatory treatment regimens for ovulation induction in anovulatory women.
authors.affiliation: Department of Medical Sciences, Uppsala University, Clinical Chemistry, University Hospital, SE 751 85 Uppsala, Sweden. leif.wide@medsci.uu.se
authors.forename: Leif
authors.initials: L
authors.lastname: Wide
authors.forename: Karin
authors.initials: K
authors.lastname: Eriksson
mesh_terms: D000328:Adult; D000858:Anovulation / Q000097:blood / Q000628:therapy; D005260:Female; D043373:Follicle Stimulating Hormone, Human / Q000097:blood* / Q000737:chemistry*; D005643:Fucose / Q000031:analogs & derivatives / Q000097:blood / Q000737:chemistry; D006031:Glycosylation; D006801:Humans; D007986:Luteinizing Hormone / Q000097:blood* / Q000737:chemistry*; D008597:Menstrual Cycle / Q000097:blood*; D010060:Ovulation / Q000097:blood*; D010062:Ovulation Induction / Q000379:methods; D011134:Polysaccharides / Q000097:blood / Q000737:chemistry; D012794:Sialic Acids / Q000097:blood / Q000737:chemistry; D055815:Young Adult
chemical_list: D043373:Follicle Stimulating Hormone, Human; D011134:Polysaccharides; D012794:Sialic Acids; D005643:Fucose; C059377:N-acetylfucosamine; D007986:Luteinizing Hormone