Does kisspeptin exert a local modulatory effect on bovine ovarian steroidogenesis?

Kisspeptin, a hypothalamic neuropeptide encoded by the KISS1 gene, has a pivotal role in promoting GnRH secretion in mammals. Kisspeptin and its receptor (KISS1R) are also expressed in certain peripheral tissues including gonads, suggesting intra-gonadal roles. Such actions at the level of the bovine ovary have not been explored previously.

Transcriptomal profiling of bovine ovarian granulosa and theca interna cells in primary culture in comparison with their in vivo counterparts.

In vitro culture of ovarian granulosa cells and theca cells has been very important for our understanding of their function and regulation. One of the most eagerly sought attributes of cell culture is the use of chemically-defined conditions. However, even under such in vitro conditions cell behaviour could differ from the in vivo situation because of differences in oxygen tension, nutrients, adhesion matrix and other factors.

The global effect of follicle-stimulating hormone and tumour necrosis factor α on gene expression in cultured bovine ovarian granulosa cells.

Background: Oocytes mature in ovarian follicles surrounded by granulosa cells. During follicle growth, granulosa cells replicate and secrete hormones, particularly steroids close to ovulation. However, most follicles cease growing and undergo atresia or regression instead of ovulating.

Ovarian expression of insulin-like peptide 3 (INSL3) and its receptor (RXFP2) during development of bovine antral follicles and corpora lutea and measurement of circulating INSL3 levels during synchronized estrous cycles.

Insulin-like peptide 3 (INSL3), a major product of testicular Leydig cells, is also expressed by the ovary, but its functional role remains poorly understood. Here, we quantified expression of INSL3 and its receptor RXFP2 in theca interna cell (TIC) and granulosa cell compartments of developing bovine antral follicles and in corpora lutea (CL). INSL3 and RXFP2 mRNA levels were much higher in TIC than granulosa cell and increased progressively during follicle maturation with INSL3 peaking in large (11-18 mm) estrogen-active follicles and RXFP2 peaking in 9- to 10-mm follicles before declining in larger (11-18 mm) follicles.

Functional link between bone morphogenetic proteins and insulin-like peptide 3 signaling in modulating ovarian androgen production.

Bone morphogenetic proteins (BMPs) are firmly implicated as intra-ovarian regulators of follicle development and steroidogenesis. Here we report a microarray analysis showing that treatment of cultured bovine theca cells (TC) with BMP6 significantly (>twofold; P < 0.01) up- or down-regulated expression of 445 genes.

The anti-epileptic drug valproic acid (VPA) inhibits steroidogenesis in bovine theca and granulosa cells in vitro.

Valproic acid (VPA) is used widely to treat epilepsy and bipolar disorder. Women undergoing VPA treatment reportedly have an increased incidence of polycystic ovarian syndrome (PCOS)-like symptoms including hyperandrogenism and oligo- or amenorrhoea. To investigate potential direct effects of VPA on ovarian steroidogenesis we used primary bovine theca (TC) and granulosa (GC) cells maintained under conditions that preserve their 'follicular' phenotype.

Changes in expression of bone morphogenetic proteins (BMPs), their receptors and inhibin co-receptor betaglycan during bovine antral follicle development: inhibin can antagonize the suppressive effect of BMPs on thecal androgen production.

We reported previously that bone morphogenetic proteins (BMPs) potently suppress CYP17 expression and androgen production by bovine theca interna cells (TC) in vitro. In this study, real-time PCR was used to analyse gene expression in TC and granulosa cell (GC) layers from developing bovine antral follicles (1-18 mm). Abundance of mRNA transcripts for four BMPs (BMP2, BMP4, BMP6, and BMP7) and associated type I (BMPR1A, BMPR1B, ACVR1 and ACVR1B) and type II (BMPR2, ACVR2A and ACVR2B) receptors showed relatively modest, though significant, changes during follicle development.

Evidence for an inhibitory role of bone morphogenetic protein(s) in the follicular-luteal transition in cattle.

Bone morphogenetic proteins (BMPs) and their receptors are expressed in ovarian theca cells (TC) and granulosa cells (GC) and BMPs have been implicated in the regulation of several aspects of follicle development including thecal androgen production and granulosal oestrogen production. Their potential involvement in luteal function has received less attention. In this study, we first compared relative abundance of mRNA transcripts for BMPs, activin-betaA and BMP/activin receptors in bovine corpus luteum (CL) and follicular theca and granulosa layers before undertaking functional in vitro experiments to test the effect of selected ligands (BMP6 and activin A) on luteinizing bovine TC and GC.

Bone morphogenetic protein-6 enhances gonadotrophin-dependent progesterone and inhibin secretion and expression of mRNA transcripts encoding gonadotrophin receptors and inhibin/activin subunits in chicken granulosa cells.

The aims were to examine ovarian expression of bone morphogenetic protein (BMP) ligands/receptor mRNAs in the chicken and to test the hypothesis that theca-derived BMP(s) modulates granulosa cell function in a paracrine manner. RT-PCR revealed expression of multiple BMPs in granulosa and theca cells from pre hierarchical and preovulatory follicles with greater expression in theca cells; both cell types expressed BMP receptors-IA, -IB and -II consistent with tissue responsiveness. Preovulatory granulosa cells (F1, F2 and F3/4) were cultured with BMP-6 (expressed by theca but not granulosa) in the presence/absence of LH, FSH or 8-Br-cAMP.

Gonadotrophins modulate hormone secretion and steady-state mRNA levels for activin receptors (type I, IIA, IIB) and inhibin co-receptor (betaglycan) in granulosa and theca cells from chicken prehierarchical and preovulatory follicles.

Ovarian follicle development is regulated through endocrine and local mechanisms. Increasing evidence indicates roles for transforming growth factor beta superfamily members, including inhibins and activins. We recently identified divergent expression of mRNAs encoding activin receptors (ActR) and inhibin co-receptor betaglycan in chicken follicles at different stages of maturation.

Bovine follicle development is associated with divergent changes in activin-A, inhibin-A and follistatin and the relative abundance of different follistatin isoforms in follicular fluid.

The aim was to determine whether follicle growth in cattle is accompanied by changes in levels of inhibin-A (inh-A), activin-A (act-A) and different Mr isoforms of follistatin (FS) in bovine follicular fluid (bFF), reflecting differential roles of these proteins during folliculogenesis. Follicles (n = 146) from 2-20 mm diameter were dissected from ovaries of approximately 40 cattle. Immunoassays were used to measure total FS, act-A, inh-A, oestradiol (E) and progesterone (P) levels; immunoblotting was used to quantify the relative abundance of different FS isoforms.

Bone morphogenetic proteins (BMP) -4, -6, and -7 potently suppress basal and luteinizing hormone-induced androgen production by bovine theca interna cells in primary culture: could ovarian hyperandrogenic dysfunction be caused by a defect in thecal BMP signaling?

We reported recently that bovine theca interna cells in primary culture express several type-I and type-II receptors for bone morphogenetic proteins (BMPs). The same cells express at least two potential ligands for these receptors (BMP-4 and -7), whereas bovine granulosa cells and oocytes express BMP-6. Therefore, BMPs of intrafollicular origin may exert autocrine/paracrine actions to modulate theca cell function.

Association between ovarian follicle development and pregnancy rates in dairy cows undergoing spontaneous oestrous cycles.

Ovarian follicle development continues in a wave-like manner during the bovine oestrous cycle giving rise to variation in the duration of ovulatory follicle development. The objectives of the present study were to determine whether a relationship exists between the duration of ovulatory follicle development and pregnancy rates following artificial insemination (AI) in dairy cows undergoing spontaneous oestrous cycles, and to identify factors influencing follicle turnover and pregnancy rate and the relationship between these two variables. Follicle development was monitored by daily transrectal ultrasonography from 10 days after oestrus until the subsequent oestrus in 158 lactating dairy cows.

Bone morphogenetic protein (BMP) ligands and receptors in bovine ovarian follicle cells: actions of BMP-4, -6 and -7 on granulosa cells and differential modulation of Smad-1 phosphorylation by follistatin.

Given the paucity of information on the potential roles of bone morphogenetic proteins (BMPs) in the ruminant ovary we conducted immunolocalization and functional studies on cells isolated from bovine antral follicles. Immunocytochemistry revealed expression of BMP-4 and -7 in isolated theca cells whereas granulosa cells and oocytes selectively expressed BMP-6. All three cell types expressed a range of BMP-responsive type-I (BMPRIB, ActRI) and type-II (BMPRII, ActRII, ActRIIB) receptors supporting autocrine/paracrine roles within the follicle.

Local roles of TGF-beta superfamily members in the control of ovarian follicle development.

Members of the transforming growth factor-beta (TGF-beta) superfamily have wide-ranging influences on many tissue and organ systems including the ovary. Two recently discovered TGF-beta superfamily members, growth/differentiation factor-9 (GDF-9) and bone morphogenetic protein-15 (BMP-15; also designated as GDF-9B) are expressed in an oocyte-specific manner from a very early stage and play a key role in promoting follicle growth beyond the primary stage. Follicle growth to the small antral stage does not require gonadotrophins but appears to be driven by local autocrine/paracrine signals from both somatic cell types (granulosa and theca) and from the oocyte.

Oocyte-mediated suppression of follicle-stimulating hormone- and insulin-like growth factor-induced secretion of steroids and inhibin-related proteins by bovine granulosa cells in vitro: possible role of transforming growth factor alpha.

The objective was to investigate the potential role of the oocyte in modulating proliferation and basal, FSH-induced and insulin-like growth factor (IGF)-induced secretion of inhibin A (inh A), activin A (act A), follistatin (FS), estradiol (E(2)), and progesterone (P(4)) by mural bovine granulosa cells. Cells from 4- to 6-mm follicles were cultured in serum-free medium containing insulin and androstenedione, and the effects of ovine FSH and IGF analogue (LR3-IGF-1) were tested alone and in the presence of denuded bovine oocytes (2, 8, or 20 per well). Medium was changed every 48 h, cultures were terminated after 144 h, and viable cell number was determined.

Women with poor response to IVF have lowered circulating gonadotrophin surge-attenuating factor (GnSAF) bioactivity during spontaneous and stimulated cycles.

Background: Up to 13% of IVF cancellations are due to poor responses during down-regulated cycles. Because premature luteinization occurs more frequently in older or "poor responder" patients, defective production of gonadotrophin surge-attenuating factor (GnSAF) may be involved.

Methods: Nine women with normal previous IVF response (NORM) and 9 with previous poor IVF response (POOR) were monitored in a spontaneous cycle (blood samples: days 2, 7, 11, 15 and 20) and then stimulated with recombinant human FSH (rFSH) under GnRH agonist (blood samples: treatment days GnRH agonist + 2, GnRH agonist + 7, day of HCG administration and days HCG + 1 and HCG + 8).