Granulosa cell aromatase bioassay: changes of bioactive FSH levels in the female

Is there any physiological role for gonadotrophin oligosaccharide heterogeneity in humans? I. Gondatrophins are synthesized and released in multiple molecular forms. A matter of fact

Carbohydrates attached to the protein core of all glycoprotein hormones play an essential role in the function of the molecule, influencing a number of intracellular and extracellular processes. As with other members of the glycoprotein hormone family, pituitary gonadotrophins are not produced as single or unique molecules but rather as arrays of isoforms that differ from each other mainly in the structure of their oligosaccharide attachments. In both experimental animals and in humans, the abundance of the different isoforms varies depending on the endocrine status of the donor present at the time of collection of the tissue or sample. Conditions characterized by an oestrogen-enriched hormonal milieu (eg. the preovulatory phase of the menstrual cycle) promote the formation and secretion of variants with relatively low sialic acid and/or sulphate content, whereas physiological deficiency of this sex steroid (as in the postmenopause) favours the production of highly sialylated, long-lived gonadotrophin variants. When tested individually, less sialylated isoforms exhibit higher receptor-binding and in-vitro biological activity but shorter plasma half-life than their more sialylated counterparts. Both the hormonal regulation and the functional differences among the naturally occurring isoforms strongly suggest that gonadotrophin heterogeneity represents a distinctly different mechanism through which the pituitary gland may regulate the intensity and duration of the gonadotrophic stimulus. Nevertheless, whereas the existence of the alternatively glycosylated variants of gonadotrophins in both the pituitary and in serum is currently without doubt, the physiological role of this phenomenon is still a controversial issue and a matter of debate.

Urinary follicle-stimulating hormone (FSH) versus recombinant FSH in clomiphene citrate-resistant, normogonadotropic,chronic anovulation: a prospective randomized study

OBJECTIVE

To compare the efficacy and safety of urinary FSH and recombinant FSH for ovulation induction in patients with clomiphene citrate-resistant, normogonadotropic, chronic anovulation.

DESIGN

Prospective, randomized trial.

SETTING

University-based infertility clinic.

PATIENT(S)

Fifty-one women.

INTERVENTION(S)

Subjects were randomized to receive either urinary FSH (35 patients, 64 cycles) or recombinant FSH (16 patients, 32 cycles). A maximum of three cycles using the low-dose step-up protocol with the same gonadotropin were undertaken.

MAIN OUTCOME MEASURE(S)

Cumulative ovulation and pregnancy rates after three cycles, total gonadotropin dose, duration of stimulation, and single follicle development rate.

RESULT(S)

Cumulative ovulation rates were 89.3% and 93.1% for the urinary FSH and recombinant FSH groups, respectively. The threshold and total doses of FSH and the duration of stimulation were similar between the two groups. Significantly more single follicle development was noted in the recombinant FSH group. The respective clinical pregnancy rates per noncanceled cycles in the urinary FSH and recombinant FSH groups were 23.2% and 27.6%. There were three sets of twins in the urinary FSH group. No case of ovarian hyperstimulation syndrome was encountered.

CONCLUSION(S)

Urinary FSH and recombinant FSH are both efficient and safe for inducing ovulation with the low-dose step-up protocol.

Developmental patterns of bioactive and immunoreactive FSH in the female rabbit: effects of ovariectomy

A longitudinal study was performed to determine the relationship between immunoreactive and biologically active FSH in the serum of sham-operated and ovariectomized female rabbits. Twenty-two-day-old female rabbits, 8 per group, were sham-operated or bilaterally ovariectomized on day 23. Blood was taken every 3-4 days from each rabbit until they achieved a weight of 3 kg or age 100 days. Sera were analysed by radioimmunoassay for LH and FSH or for bioactive FSH. In sham-operated animals, immuno-FSH levels showed a 10-fold increase from 0.36 +/- 0.04 ng/ml to greater than 35 ng/ml between days 45 and 80. By contrast, bio-FSH levels increased more gradually from a baseline of 5.4 +/- 0.4 ng/ml to about 8 ng/ml. Bilateral ovariectomy resulted in a significant increase in both bio-FSH, 5.5 +/- 0.4 ng/ml to 12.6 +/- 1.5 ng/ml and immuno-FSH levels from 0.4 ng/ml to 5.2 +/- 1.4 ng/ml 24 h later. These levels of FSH remained elevated throughout the sampling period in both groups of animals and then decreased after day 100. Peripheral LH levels showed much more variation but were 2-fold higher in ovariectomized rabbits, 0.4-1.4 ng/ml in sham-operated vs. 0.8-2.4 ng/ml in ovariectomized rabbits. These results emphasize the marked variations in FSH levels according to the method of analysis. They also suggest that extra-ovarian factors may play a role in inhibiting gonadotropin release especially LH.