Effect of the human follicle-stimulating hormone-binding inhibitor and its N-terminal fragment on follicle-stimulating hormone-induced progesterone secretion by granulosa cells in vitro

Abstract

Intrafollicular factors play an important role in folliculogenesis. The follicle-stimulating hormone (FSH)-binding inhibitor (FSHBI), purified by our laboratory from human ovarian follicular fluid, has been shown to suppress ovulation and induce follicular atresia/apoptosis in mice as well as impair fertility in marmosets, the New World monkeys. The octapeptide, a peptide corresponding to the N-terminal region of human FSHBI (hFSHBI), has been synthesized and also shows FSHBI activity in vitro. In the present study, we have attempted to identify the mechanism of action of the peptide in granulosa cell cultures. Rat granulosa cell cultures were treated with varying concentrations of the octapeptide or partially purified hFSHBI (gel chromatography fraction hGF 2) in the presence or absence of human FSH (hFSH) and the amount of progesterone (P;4) secreted in the culture supernatants after 3 h/48 h was estimated. Both hGF2 and the octapeptide failed to alter basal levels as well as 8-bromo cAMP-induced P;4 production, while FSH-induced P 4 secretion was inhibited in a dose-dependent manner. These studies reveal that the octapeptide, a fragment of FSHBI, and the native protein have similar activity in vitro and both compounds alter FSH action at the receptor level upstream of cAMP formation.

Granulosa Cell Apoptosis Induced by a Novel FSH Binding Inhibitory Peptide From Human Ovarian Follicular Fluid

“…However, in the OP-treated group, maximum apoptosis was observed in cumulus granulosa cells. This observation may corroborate our earlier findings that there is a drastic decrease in progesterone (P 4 ) secretion by granulosa cells when cultured in the presence of OP (Wadia et al 2007). Khamsi and Roberge (2001) reported that cumulus granulosa cells have the potential to secrete six times more progesterone compared with antral or basal granulosa cells.…”

“…Furthermore, hGF 2 inhibited steroid production by granulosa cells (Wadia et al 2007), indicating an autocrine role of the peptide on granulosa cells of the follicles. Its ability to modulate ovarian function strengthens the need to understand its mechanism of action.…”

Whole sheep ovary cryopreservation: evaluation of a slow freezing protocol with dimethylsulphoxide

“…However, it is likely that the differences in progesterone secretion would have been more pronounced after a longer perfusion period since this only partly involve the cAMP second messenger system. An additional method for evaluation of function and viability of ovarian tissue is ovarian cell culture with measurements of steroid secretion [45,46]. In the present study we cultured a mixture of all ovarian cell types, which is an established method to study ovarian function when cooperation between different cell types is needed [41].…”

FSHR and LHR Expression and Signaling as Well as Maturation and Apoptosis of Cumulus-Oocyte Complexes Following Treatment with FSH Receptor Binding Inhibitor in Sheep

“…This FRBI, as an FSH antagonist, blocks the binding of hFSH to rat granulosa cells. In vivo administration of FRBI caused the suppression of ovulation and induced follicular atresia in mice [7], further impaired fertility of marmosets at doses of 100µg/day and 300µg/day [9]. …”