Human chorionic gonadotropin controls luteal vascular permeability via vascular endothelial growth factor by down-regulation of a cascade of adhesion proteins.

Objective: To study the functional interactions of junctional proteins acting as regulators of vascular permeability in the human corpus luteum. We investigated the role of vascular endothelial (VE)-cadherin, nectin 2, and claudin 5 as controllers of vascular endothelial cell permeability.

Design: Performing immunohistochemical dual staining, we colocalized the above-mentioned proteins in the human corpus luteum.

Inhibition of delta-like ligand 4 induces luteal hypervascularization followed by functional and structural luteolysis in the primate ovary.

Using specific inhibitors established that angiogenesis in the ovarian follicle and corpus luteum is driven by vascular endothelial growth factor. Recently, it has been demonstrated that the Notch ligand, delta-like ligand 4 (Dll4) negatively regulates vascular endothelial growth factor-mediated vessel sprouting and branching. To investigate the role of Dll4 in regulation of the ovarian vasculature, we administered a neutralizing antibody to Dll4 to marmosets at the periovulatory period.

Conditional ablation of macrophages disrupts ovarian vasculature.

Macrophages are the most abundant immune cell within the ovary. Their dynamic distribution throughout the ovarian cycle and heterogenic array of functions suggest the involvement in various ovarian processes, but their functional role has yet to be fully established. The aim was to induce conditional macrophage ablation to elucidate the putative role of macrophages in maintaining the integrity of ovarian vasculature.

A comparison of the imaging performance of high resolution ultrasound scanners for preclinical imaging.

Nine ultrasound transducers from six ultrasound scanners were assessed for their utility for preclinical ultrasound imaging. The transducers were: L8-16, L10-22 (Diasus; Dynamic Imaging Ltd., Livingston, UK); L17-5, L15-7io (iU22; Philips, Seattle, WA, USA), HFL38/13-6 (MicroMaxx; Sonosite Inc.

Inhibition of vascular endothelial growth factor during the postovulatory period prevents pregnancy in the marmoset.

Background: This study investigated the effects of inhibition of vascular endothelial growth factor (VEGF) during the first postpartum cycle in marmosets housed with a fertile male where a 90% fertility rate is normal.

Methods: On resumption of mating, females were treated with either 25 mg/kg aflibercept, a potent VEGF inhibitor, or control Fc protein (n=6 per group) at the time of ovulation. Effects on timing of pregnancy were monitored by measuring plasma progesterone, chorionic gonadotropin (CG) and uterine palpation.

A thrombospondin-mimetic peptide, ABT-898, suppresses angiogenesis and promotes follicular atresia in pre- and early-antral follicles in vivo.

Using a novel in vitro angiogenesis assay, we previously showed that thrombospondin (TSP)-1 has antiangiogenic effects on rat follicles and induces apoptosis in granulosa cells in vitro. ABT-898 is an octapeptide mimetic of TSP-1 closely related to ABT-510. Here, we demonstrate the inhibitory effects of ABT-898 on follicular angiogenesis and its proapoptotic effect on granulosa cells.

Identification of androgen receptor phosphorylation in the primate ovary in vivo.

The androgen receptor (AR) is a member of the nuclear receptor superfamily, and is important for both male and female reproductive health. The receptor is a target for a number of post-translational modifications including phosphorylation, which has been intensively studied in vitro. However, little is known about the phosphorylation status of the receptor in target tissues in vivo.

Thrombospondin-1 inhibits angiogenesis and promotes follicular atresia in a novel in vitro angiogenesis assay.

Thrombospondin-1 (TSP-1) is a putative antiangiogenic factor, but its role in regulating physiological angiogenesis is unclear. We have developed a novel in vitro angiogenesis assay to study the effect of TSP-1 on follicular angiogenesis and development. Intact preantral/early antral follicles dissected from 21-d-old rat ovaries were cultured for 6 d in the presence or absence of TSP-1.

SRB Reproduction, Fertility and Development Award Lecture 2008. Regulation and manipulation of angiogenesis in the ovary and endometrium.

The marked cyclical physiological angiogenesis in the developing follicle, corpus luteum and endometrium implies a critical role in health and disease. Our approach to understanding its regulation has been to localise and quantify the temporal changes in putative angiogenic factors, and their receptors, in human and non-human primate tissue and to use antagonists to dissect their role by specific inhibition at defined periods during the ovulatory cycle in non-human primates in vivo. The course of angiogenesis throughout the cycle and the cellular and molecular effects of inhibitory treatments have been investigated in the marmoset ovary and uterus, whereas consequences on pituitary-ovarian function have been monitored in macaques.

The role of vascular endothelial growth factor and estradiol in the regulation of endometrial angiogenesis and cell proliferation in the marmoset.

The present studies explore the roles of vascular endothelial growth factor (VEGF) and estradiol on angiogenesis and stromal and epithelial cell proliferation in the marmoset endometrium during the proliferative phase of the ovulatory cycle. At the start of the proliferative phase, marmosets were 1) treated with vehicle, 2) treated with a VEGF inhibitor (VEGF Trap, aflibercept), 3) ovariectomized, 4) ovariectomized and given replacement estradiol, or 5) treated with VEGF Trap and given replacement estradiol. The uterus was examined 10 d later in the late proliferative phase.

Inhibition of vascular endothelial growth factor in the primate ovary up-regulates hypoxia-inducible factor-1alpha in the follicle and corpus luteum.

Vascular endothelial growth factor (VEGF)-dependent angiogenesis is crucial for follicular growth, and corpus luteum formation and function, in the primate ovary. In the ovary VEGF can be hormonally regulated, but in other systems, the main regulator of VEGF expression is hypoxia. We hypothesized that hypoxia was involved in the regulation of angiogenesis in the cycling ovary.

Thrombospondin-1 expression is increased during follicular atresia in the primate ovary.

Thrombospondin (TSP)-1 is an antiangiogenic extracellular matrix glycoprotein that modulates several aspects of cellular function. The aim of this study was to determine the pattern of TSP-1 mRNA and protein expression as well as expression of its receptor CD36 in the marmoset ovary and to investigate the effects of inhibition of gonadotropins or VEGF activity on TSP-1 and CD36 expression in vivo. GnRH antagonist or VEGF Trap, a soluble decoy receptor, was administered on d 0 of the follicular phase of the cycle, and ovaries were collected at the end of the follicular phase (d 10).

Oestrogen and progesterone receptors in the marmoset endometrium: changes during the ovulatory cycle, early pregnancy and after inhibition of vascular endothelial growth factor, GnRH or ovariectomy.

Marmosets are widely used, but detailed studies on localisation of endometrial oestrogen receptors alpha and beta (ER alpha and ER beta ), and the progesterone receptor (PR) are lacking. These receptors were localised and semi-quantitatively analysed throughout the ovulatory cycle, weeks 2, 3 and 4 of pregnancy and after treatment with GnRH antagonist, vascular endothelial growth factor (VEGF) Trap or ovariectomy. The PR in epithelial cells increased markedly between the mid- and late proliferative phases before declining in the mid-secretory phase and pregnancy.

In vitro evidence suggests activin-A may promote tissue remodeling associated with human luteolysis.

Luteolysis in women is associated with an up-regulation of the expression and activity of matrix metalloproteinase-2 (MMP-2), which is inhibited by human chorionic gonadotropin (hCG) during maternal recognition of pregnancy. Because the primary source of MMP-2 is fibroblasts that do not express LH/hCG receptors, we aimed to investigate the regulation of MMP-2. Women with regular cycles having hysterectomy for nonmalignant conditions and women undergoing oocyte retrieval for assisted conception were used in this current study.

Expression of anti-Mullerian hormone protein during early follicular development in the primate ovary in vivo is influenced by suppression of gonadotropin secretion and inhibition of vascular endothelial growth factor.

Anti-Mullerian hormone (AMH) plays a role during early follicular development and selection. The aim of this study was to determine the pattern of AMH protein expression in the marmoset ovary and to investigate the effects of inhibition of gonadotropins or vascular endothelial growth factor (VEGF) activity on AMH expression in vivo. GnRH antagonist or VEGF Trap, a soluble decoy receptor, was administered on d 0 or 5 of the follicular phase of the cycle, and ovaries were collected at the end of the follicular phase (d 10).

Administration of vascular endothelial growth factor Trap during the 'post-angiogenic' period of the luteal phase causes rapid functional luteolysis and selective endothelial cell death in the marmoset.

The intense angiogenesis characteristic of early corpus luteum development is dependent upon vascular endothelial growth factor (VEGF) as inhibitors of VEGF administered at the peri-ovulatory period suppress endothelial cell proliferation and progesterone secretion. We now report that administration of VEGF Trap, a soluble decoy receptor-based inhibitor, at the mid- or the late luteal phase in the marmoset results in a rapid decline in plasma progesterone. Since vascularisation of the corpus luteum is largely complete by the mid-luteal phase, it suggested that this functional luteolysis involved mechanisms other than inhibition of angiogenesis.

Regulation of the ovarian follicular vasculature.

Angiogenesis is associated with follicular development and is regulated independently within each follicle potentially making the functioning of its vasculature critically important in determining its fate. This review examines the various ways in which follicular angiogenesis may be monitored, describes the follicular localisation and changes in pro- and anti-angiogenic factors that may regulate the process and how antagonists may be used to elucidate their physiological role in vivo. Thus, inhibition of vascular endothelial growth factor (VEGF), VEGF receptor-2, vascular endothelial cell cadherin or interference with the angiopoietin system can inhibit follicular development or prevent ovulation.

Vascular morphogenesis in the primate ovary.

Ovarian function is dependent on intense cyclical vascular morphogenesis and regression. The molecular and cellular pathways involved in the generation of new capillary networks in the ovary are now being elucidated. Focussing on the marmoset, the course of angiogenesis at different stages of follicular maturation and in the corpus luteum throughout the cycle and in early pregnancy have been quantified and major progress has been made in the evaluation of the role of vascular endothelial growth factor (VEGF).

Bifunctional gonadotropin-releasing hormone antagonist-progesterone analogs with increased efficacy and duration of action.

GnRH peptide analogs are widely used to treat diverse clinical conditions. However, they have poor oral activity and exhibit rapid metabolic clearance, thus requiring injection and depot formulation. Because steroid hormones are bound to plasma proteins, we explored the possibility of conjugating hydroxylated progesterones to GnRH analogs to reduce metabolic clearance of the peptides.

Endocrine regulation of menstruation.

In women, endometrial morphology and function undergo characteristic changes every menstrual cycle. These changes are crucial for perpetuation of the species and are orchestrated to prepare the endometrium for implantation of a conceptus. In the absence of pregnancy, the human endometrium is sloughed off at menstruation over a period of a few days.

Vascular endothelial growth factor Trap suppresses ovarian function at all stages of the luteal phase in the macaque.

Context: Fertility is dependent on a functioning corpus luteum, the formation of which is associated with intense angiogenesis. The role of angiogenic factors, such as vascular endothelial growth factor (VEGF), in luteal function has yet to be defined in primates.

Objective: The objective of this study was to determine effects of inhibiting VEGF by a VEGF Trap, a receptor-based inhibitor, administered at the early or midluteal phase, on pituitary-ovarian function.

Connective tissue growth factor expression in the human corpus luteum: paracrine regulation by human chorionic gonadotropin.

Context: The molecular mechanisms of luteolysis and its inhibition during maternal recognition of pregnancy remain unclear.

Objective: The objective of this study was to investigate the differential regulation of connective tissue growth factor (CTGF) expression in human corpora lutea using in vivo and in vitro models.

Design: Corpora lutea from different stages of the luteal phase and after luteal rescue with human chorionic gonadotropin (hCG) were studied.

Single injections of vascular endothelial growth factor trap block ovulation in the macaque and produce a prolonged, dose-related suppression of ovarian function.

Follicular development is associated with intense angiogenesis and increased permeability of blood vessels under the control of locally produced angiogenic factors such as vascular endothelial growth factor (VEGF). The aim of the present study was to evaluate the effects of transient inhibition of VEGF on pituitary-ovarian function in the macaque. Animals were given a single, iv injection of a potent, receptor-based VEGF antagonist, the VEGF Trap.

Localization and quantification of cyclic changes in the expression of endocrine gland vascular endothelial growth factor in the human corpus luteum.

Angiogenesis is essential for normal growth and function of the corpus luteum. The roles of various angiogenic factors in these events are being elucidated. Endocrine gland vascular endothelial growth factor (EG-VEGF) has recently been described in the human ovary.

Angiogenesis and microvascular development in the marmoset (Callithrix jacchus) endometrium during early pregnancy.

The aim of the study was to describe and quantify the changes in the maternal vasculature and angiogenesis during early pregnancy in the marmoset endometrium using bromodeoxyuridine (BrdU) to identify proliferating cells, CD31 to label endothelial cells and dual staining to identify proliferating endothelial cells. Non-pregnant animals from mid- and late secretory stages were studied and compared with pregnant animals at weeks 2, 3 and 4 of pregnancy. Qualitative and morphometric analyses of angiogenesis and vascular area were performed.