Carbohydrate complexity and proportion of serum FSH isoforms reflect pituitary-ovarian activity in perimenopausal women and depot medroxyprogesterone acetate users.
BACKGROUND
FSH is synthesized and secreted in multiple glycosylation variants with different oligosaccharide structures; the endocrine milieu regulates the composition of FSH carbohydrate moiety.


OBJECTIVE
To characterize serum FSH isoforms according to their sialic acid content and oligosaccharide complexity in regularly menstruating women and in depot medroxyprogesterone acetate (DMPA) users during the menopausal transition. Subjects and methods Ten regularly menstruating perimenopausal women aged 45-52, with mid-follicular phase FSH levels < or =10 IU/l and 10 regularly menstruating women, aged 20-39, were included. Blood samples were collected on the ninth day of the menstrual cycle. Twenty DMPA users were divided into two groups (n = 10) according to age: DMPA(1), age range 20-39 and DMPA(2), age range 45-52. Blood samples were collected 90 +/- 5 days after the last injection of DMPA. Oestradiol (E(2)), inhibin B (Inh B), Pro-alphaC levels and the relative abundance of FSH isoforms on the basis of charge (preparative isoelectric focusing) and carbohydrate complexity (Concanavalin A chromatography) were determined.


RESULTS
Decreased Inh B and moderately elevated E(2) levels were observed in perimenopausal women associated with an increase in FSH sialylation and a decrease in its oligosaccharide complexity. DMPA induced changes in the hormonal profile and FSH molecular microheterogeneity; the secreted hormone was more heterogeneous and its oligosaccharides were less complex under this condition.


CONCLUSIONS
Serum FSH glycoforms with increased sialylation and decreased oligosaccharide complexity reflect the decline of the gonadal activity induced either by age or by the use of a DMPA as a contraceptive.
Loreti
Nazareth
N
Centro de Investigaciones Endocrinológicas (CEDIE), CONICET, Hospital de Niños R. Gutiérrez, Ciudad de Buenos Aires, Argentina.
Ambao
Verónica
V
Juliato
Cassia Teatin
CT
Machado
Cecilia
C
Bahamondes
Luis
L
Campo
Stella
S
D003692:Delayed-Action Preparations; D004958:Estradiol / Q000097:blood; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood* / Q000737:chemistry; D006031:Glycosylation; D006801:Humans; D007265:Inhibins / Q000097:blood; D017258:Medroxyprogesterone Acetate / Q000008:administration & dosage*; D008875:Middle Aged; D019158:N-Acetylneuraminic Acid / Q000097:blood; D009844:Oligosaccharides / Q000097:blood* / Q000737:chemistry; D010053:Ovary / Q000503:physiopathology*; D047648:Perimenopause / Q000502:physiology*; D010902:Pituitary Gland / Q000503:physiopathology*; D020033:Protein Isoforms / Q000097:blood / Q000737:chemistry
D003692:Delayed-Action Preparations; D009844:Oligosaccharides; D020033:Protein Isoforms; C422364:inhibin B; D004958:Estradiol; D007265:Inhibins; D005640:Follicle Stimulating Hormone; D017258:Medroxyprogesterone Acetate; D019158:N-Acetylneuraminic Acid