17 beta-oestradiol counteracts the formation of the more acidic isoforms of follicle-stimulating hormone and luteinizing hormone after menopause.
OBJECTIVE
When the gonadotrophin levels increase at midcycle, more basic isoforms of FSH and LH appear in the circulation. However, when these gonadotrophins increase at menopause more acidic forms appear. The present study was done to see whether chronic 17 beta-oestradiol (E2) administration to post-menopausal women could counteract the formation of the more acidic isoforms after the menopause.


METHODS
Serum samples were obtained from 16 post-menopausal women, mean age 70 years (range 63-84 years), 46-169 days after the subcutaneous insertion of a 20-mg E2-implant. FSH, LH and E2 in the sera were measured with fluoroimmunoassays. The median charge and the degree of charge heterogeneity of the FSH and LH isoforms were determined for each serum by electrophoresis in 0.1% agarose suspension. Sera from an age-matched control group were analysed in parallel.


RESULTS
The E2 levels in the E2-treated women were 230-570 pmol/l, within the range expected during the mid-luteal phase of the normal menstrual cycle. The mean serum FSH and LH levels were similar to normal follicular phase FSH and LH levels (8.6 and 20.8% respectively of the control group). It was estimated that individual serum specimens from both groups contained 20-30 different isoforms for both FSH and LH. The median charges of the isoforms of FSH and LH were more basic in all the E2-treated subjects than in their corresponding untreated controls. The mean median charge for FSH was close to the values for the follicular and luteal phases and that for LH close to that for the luteal phase. In some E2-treated women the isoforms were even more basic with a charge similar to that at the midcycle peak. The degree of charge heterogeneity for the E2-treated group was significantly (P < 0.001) larger than for the controls and similar to that during the normal menstrual cycle.


CONCLUSIONS
Chronic E2 administration to post-menopausal women counteracted the formation of more acidic isoforms of both FSH and LH after the menopause.
Wide
L
L
Department of Clinical Chemistry, University Hospital, Uppsala, Sweden.
Naessén
T
T
D000368:Aged; D000369:Aged, 80 and over; D004343:Drug Implants; D004587:Electrophoresis, Agar Gel; D004958:Estradiol / Q000097:blood / Q000627:therapeutic use*; D015914:Estrogen Replacement Therapy; D005260:Female; D015200:Fluoroimmunoassay; D005640:Follicle Stimulating Hormone / Q000097:blood; D006065:Gonadotropins, Pituitary / Q000097:blood*; D006801:Humans; D007986:Luteinizing Hormone / Q000097:blood; D008593:Menopause / Q000097:blood*; D008875:Middle Aged; D012016:Reference Values
D004343:Drug Implants; D006065:Gonadotropins, Pituitary; D004958:Estradiol; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone