Dopamine receptor 2 activation inhibits ovarian vascular endothelial growth factor secretion in an ovarian hyperstimulation syndrome (OHSS) animal model: implications for treatment of OHSS with dopamine receptor 2 agonists

Cocktail treatment by GnRH-antagonist, letrozole, and mifepristone for the prevention of ovarian hyperstimulation syndrome: a prospective randomized trial

OBJECTIVE

This study is aimed to determine the efficacy of a cocktail style treatment by combining GnRH-antagonist, letrozole, and mifepristone on the prevention of ovarian hyperstimulation syndrome (OHSS) in high-risk women.

METHODS

This prospective, randomized controlled clinical trial was performed between January 2018 and December 2018. A total of 170 women who identified as high risk of OHSS during the ovarian hyperstimulation and underwent cryopreservation of whole embryos. On the day of oocyte retrieval, the combination group received 0.25 mg Cetrorelix for 3 d, 5 mg letrozole for 5 d, and 50 mg mifepristone for 3 d, the mifepristone group received 50 mg mifepristone for 3 d. A total of 156 cases were included in final analysis. All the frozen embryo transfer (FET) cycles were followed up until December 2021.

RESULTS

The combination group showed significantly decreased incidence of moderate and severe OHSS than mifepristone group (20.5% vs. 42.3%), with remarkably reduced serum estradiol level on hCG + 3 and + 5 d, decreased ovarian diameter, and shortened luteal phase. Oocyte retrieval number, levels of estradiol on hCG + 0 and VEGF, and ovarian diameter on hCG + 5 were associated with the severity of the symptoms. There was no significant difference in cumulative live birth rates (LBRs) between the combination and mifepristone group (74.4% vs. 76.9%).

CONCLUSIONS

The combination treatment effectively reduces the incidence of moderate/severe OHSS in high-risk women.

Does cabergoline administration affect endometrial VEGFR-2 expression in a rat model of ovarian hyperstimulation syndrome?

OBJECTIVE

To assess the effect of cabergoline on endometrial vascular endothelial growth factor receptor-2 (VEGFR-2) immunoexpression in an ovarian hyperstimulation syndrome (OHSS) rat model.

MATERIAL AND METHODS

Twenty-one immature female Wistar rats were assigned into three groups: group 1, the control group; group 2, stimulated with gonadotropins to mimic OHSS; and group 3, in which an OHSS protocol was induced and thereafter treated with cabergoline (100 μg/kg/day). Body weight, ovarian volume, corpora lutea numbers, and endometrial VEGFR-2 expression were compared between the groups.

RESULTS

Weight gain and ovarian volume were highest in the OHSS-placebo group, while cabergoline administration significantly reversed those effects (p = 0.001 and p = 0.001, respectively). VEGFR-2 stained cells were significantly lower in groups 2 and 3 compared to group 1 (p = 0.002). Although VEGFR-2 expression was lowest in group 3, the difference was not statistically significant. Corpora lutea numbers were also similar (p = 0.465).

CONCLUSION

While successful implantation requires a vascularized receptive endometrium, impaired expression of VEGFR-2 and disrupted endometrial angiogenesis due to cabergoline administration may be associated with IVF failure in fresh OHSS cycles. The insignificant decrease in endometrial VEGFR-2 expression observed in this research needs to be investigated by further studies involving additional techniques such as immunoblotting and/or RT-PCR analyses.

Treatment of Ovarian Hyperstimulation Syndrome in a Mouse Model by Cannabidiol, an Angiogenesis Pathway Inhibitor

Studies suggest that ovarian hyperstimulation syndrome (OHSS) can be treated by reducing the level of vascular endothelial growth factor (VEGF). However, due to the side effects of commercially available VEGF-reducing drugs, they can be ruled out as a suitable treatment for OHSS; therefore, researchers are looking for new medications to treat OHSS. This study is aimed at investigating the effects of cannabidiol (CBD) in an OHSS model and to evaluate its efficacy in modulating the angiogenesis pathway and VEGF gene expression. For this purpose, 32 female mice were randomly divided into four groups (eight mice per group): control group, group 2 with OHSS induction, group 3 receiving 32 nmol of dimethyl sulfoxide after OHSS induction, and group 4 receiving 30 mg/kg of CBD after OHSS induction. The animals' body weight, ovarian weight, vascular permeability (VP), and ovarian follicle count were measured, and the levels of VEGF gene and protein expression in the peritoneal fluid were assessed. Based on the results, CBD decreased the body and ovarian weights, VP, and corpus luteum number compared to the OHSS group (p < 0.05). The peritoneal VEGF gene and protein expression levels reduced in the CBD group compared to the OHSS group (p < 0.05). Also, CBD caused OHSS alleviation by suppressing VEGF expression and VP. Overall, CBD downregulated VEGF gene expression and improved VP in OHSS.

In Vitro Fertilization for Polycystic Ovarian Syndrome

In vitro fertilization is indicated for infertile women with polycystic ovarian syndrome (PCOS) after unsuccessful treatment with ovulation induction agents or in women deemed high-risk of multiple gestations who are ideal candidates for single embryo transfers. PCOS patients are at increased risk of ovarian hyperstimulation syndrome; therefore, attention should be made in the choice of in vitro fertilization treatment protocol, dose of gonadotropin utilized, and regimen to achieve final oocyte maturation. Adopting these strategies in addition to close monitoring may significantly reduce the ovarian hyperstimulation syndrome risk. Future developments may improve pregnancy outcomes and decrease complications in PCOS women undergoing fertility treatment.

Oxytocin and cabergoline alleviate ovarian hyperstimulation syndrome (OHSS) by suppressing vascular endothelial growth factor (VEGF) in an experimental model

PURPOSE

Ovarian hyperstimulation syndrome (OHSS) is a life-threatening complication of ovarian stimulation in reproductive medicine. Here, we aimed to investigate the role of oxytocin (OT) and cabergoline in the prevention and alleviation of the OHSS in an animal model.

METHODS

Thirty-five female immature Wistar rats were randomly assigned to five groups. The control group (n = 7) received saline only for five consecutive days. Remaining twenty-eight rats received 10 IU of pregnant mare serum gonadotropin (PMSG) followed by 30 IU of human chorionic gonadotropin (hCG) to induce OHSS. Group 2 (n = 7) was managed with no additional intervention after the induction of OHSS. Group 3 (n = 7) received 100 μg/kg cabergoline 2 h before the PMSG injection for four consecutive days and 2 h before the hCG injection on the fifth day. Group 4 (n = 7) and group 5 (n = 7) received 80 μg/kg and 160 μg/kg OT after induction of OHSS, respectively. Oxytocin was administered 2 h before the PMSG injection for four consecutive days and 2 h before the hCG injection on the fifth day. Body and ovary weight, vascular permeability (VP), VEGF expression in the ovaries, and levels of VEGF in the peritoneal fluids were examined in all animals.

RESULTS

Cabergoline and OT reduced body weight, ovary weight, and VP compared to that of the OHSS group (p < 0.05). VEGF expressions in ovaries and peritoneal VEGF levels were decreased in cabergoline and OT groups compared to that of the OHSS groups (p < 0.001 for cabergoline and OT-80 μg/kg; p < 0.00001 for OT-160 μg/kg). However, there was no statistically significant difference in these parameters between the OT and cabergoline groups.

CONCLUSION

Both OT and cabergoline were active in the alleviation of OHSS through suppression of VEGF and VP. Overall, we conclude that OT is effective for downregulation for VEGF and improvement in vascular permeability in OHSS.

Novel Detection and Restorative Levodopa Treatment for Preclinical Diabetic Retinopathy

Diabetic retinopathy (DR) is diagnosed clinically by directly viewing retinal vascular changes during ophthalmoscopy or through fundus photographs. However, electroretinography (ERG) studies in humans and rodents have revealed that retinal dysfunction is demonstrable prior to the development of visible vascular defects. Specifically, delays in dark-adapted ERG oscillatory potential (OP) implicit times in response to dim-flash stimuli (<-1.8 log cd · s/m²) occur prior to clinically recognized DR. Animal studies suggest that retinal dopamine deficiency underlies these early functional deficits. In this study, we randomized individuals with diabetes, without clinically detectable retinopathy, to treatment with either low- or high-dose Sinemet (levodopa plus carbidopa) for 2 weeks and compared their ERG findings with those of control subjects (no diabetes). We assessed dim-flash-stimulated OP delays using a novel handheld ERG system (RETeval) at baseline and 2 and 4 weeks. RETeval recordings identified significant OP implicit time delays in individuals with diabetes without retinopathy compared with age-matched control subjects (P < 0.001). After 2 weeks of Sinemet treatment, OP implicit times were restored to control values, and these improvements persisted even after a 2-week washout. We conclude that detection of dim-flash OP delays could provide early detection of DR and that Sinemet treatment may reverse retinal dysfunction.

Dysregulated genes and their functional pathways in luteinized granulosa cells from PCOS patients after cabergoline treatment

Polycystic ovarian syndrome (PCOS) is a common reproductive disorder frequently associated with a substantial risk factor for ovarian hyperstimulation syndrome (OHSS). Dopamine receptor 2 (D2) agonists, like cabergoline (Cb2), have been used to reduce the OHSS risk. However, lutein granulosa cells (LGCs) from PCOS patients treated with Cb2 still show a deregulated dopaminergic tone (decreased D2 expression and low dopamine production) and increased vascularization compared to non-PCOS LGCs. Therefore, to understand the PCOS ovarian physiology, it is important to explore the mechanisms that underlie syndrome based on the therapeutic effects of Cb2. Here, LGCs from non-PCOS and PCOS patients were cultured with hCG in the absence/presence of Cb2 (n = 12). Subsequently, a transcriptomic-paired design that compared untreated vs treated LGCs within each patient was performed. After transcriptomic analysis, functions and genes were prioritized by systems biology approaches and validated by RT-qPCR. We identified that similar functions were altered in both PCOS and non-PCOS LGCs treated with Cb2; however, PCOS-treated LGCs exhibited more significant changes than non-PCOS. Among the prioritized functions, dopaminergic synapse, vascular endothelial growth factor (VEGF) signaling, apoptosis and ovarian steroidogenesis were highlighted. Finally, network modeling showed CASP9, VEGFA, AKT1, CREB, AIF, MAOA, MAPK14 and BMAL1 as key genes implicated in these pathways in Cb2 response, which might be potential biomarkers for further studies in PCOS.

Pathophysiology, treatment and prevention of ovarian hyperstimulation syndrome

PURPOSE OF REVIEW

Severe ovarian hyperstimulation syndrome (OHSS) is an iatrogenic condition that affects 1% of women that undergo treatment with assisted reproductive technology. The review aims to summarize recent evidence on pathophysiology, treatment, and prevention of OHSS.

RECENT FINDINGS

The pathophysiology is still not completely understood; however, vascular endothelial growth factor is likely to be an important mediator. Human chorionic gonadotropin was previously thought to be necessary for OHSS to occur; however, recent case reports have proven otherwise. The contribution of an attenuated anti-Mullerian hormone signalling pathway and CD11c + HLA-DR + dendritic cells and associated interleukins has been explored recently as contributors to pathogenesis.Treatment is largely supportive and is based mainly on consensus statements rather than evidence. Therefore, it is important to prevent this condition by identifying women at risk, allowing the clinician to implement preventive strategies, including the use of GnRH antagonist cycles with agonist triggers.

SUMMARY

More research is required to elucidate the pathophysiology behind the condition. Clinicians should employ strategies to prevent OHSS.

Pituitary Tumor Suppression by Combination of Cabergoline and Chloroquine

CONTEXT

The dopamine agonist cabergoline (CAB) has been used widely in the treatment of prolactinomas and other types of pituitary adenomas, but its clinical use is hampered by intolerance in some patients with prolactinoma and lack of effectiveness in other pituitary tumor types. Chloroquine (CQ) is an old drug widely used to treat malaria. Recent studies, including our own, have revealed that CAB and CQ are involved in induction of autophagy and activation of autophagic cell death.

OBJECTIVE

To test whether CAB and CQ can function cooperatively to suppress growth of pituitary adenomas as well as other cancers.

RESULTS

In vitro studies using the rat pituitary tumor cell lines MMQ and GH3, human pituitary tumor cell primary cultures, and several human cancer cell lines showed that CQ enhanced suppression of cell proliferation by CAB. These results were confirmed in in vivo xenograft models in nude mice and estrogen-induced rat prolactinomas. To understand the mechanism of combined CAB and CQ action, we established a low-CAB-dose condition in which CAB was able to induce autophagy but failed to suppress cell growth. Addition of CQ to low-dose CAB blocked normal autophagic cycles and induced apoptosis, evidenced by the further accumulation of p62/caspase-8/LC3-II.

CONCLUSION

The data suggest that combined use of CAB and CQ may increase clinical effectiveness in treatment of human pituitary adenomas, as well as other cancers, making it an attractive option in tumor and cancer therapies.

Kisspeptin-10 inhibits OHSS by suppressing VEGF secretion

The aim of the present study was to elucidate the effects of kisspeptin-10 (Kp-10) on ovarian hyperstimulation syndrome (OHSS) and its related mechanism in OHSS rat models, human umbilical vein endothelial cells (HUVECs) and human luteinized granulosa cells. OHSS is a systemic disorder with high vascular permeability (VP) and ovarian enlargement. KISS1R (KISS1 receptor) is the specific receptor of kisspeptin. The kisspeptin/KISS1R system inhibits the expression of vascular endothelial growth factor (VEGF), which is the main regulator of VP. In our study, decreased expression of Kiss1r was observed in both ovaries and lung tissue of OHSS rats. Injection of exogenous Kp-10 inhibited the increase of VP and VEGF while promoting the expression of Kiss1r in both the ovarian and lung tissue of OHSS rats. Using HUVECs, we revealed that a high level of 17-β estradiol (E2), a feature of OHSS, suppressed the expression of KISS1R and increased VEGF and nitric oxide (NO) through estrogen receptors (ESR2). Furthermore, KISS1R mRNA also decreased in the luteinized human granulosa cells of high-risk OHSS patients, and was consistent with the results in rat models and HUVECs. In conclusion, Kp-10 prevents the increased VP of OHSS by the activation of KISS1R and the inhibition of VEGF.

Zinc finger gene 217 (ZNF217) Promoted Ovarian Hyperstimulation Syndrome (OHSS) through Regulating E2 Synthesis and Inhibiting Thrombospondin-1 (TSP-1)

Zinc finger gene 217 (ZNF217) is a candidate gene of polycystic ovary syndrome (PCOS) which is vulnerable to ovarian hyperstimulation syndrome (OHSS). However, the relationship between ZNF217 and OHSS is largely unknown. Our study demonstrated that ZNF217 was mainly distributed in the granulosa cells of rat ovary. Significantly higher expression of ovarian ZNF217 was detected in OHSS rats, being consistent with serum 17β-estradiol concentration and ovarian aromatase. Moreover, OHSS rats also showed decreased ovarian TSP-1 mRNA, an acknowledged VEGF signaling suppressor. The same changes were detected in human granulosa cells and follicular fluid. Thus, the increased ZNF217 and decreased TSP-1 may participate in OHSS onset. In vitro experiment revealed that ZNF217 positively regulated E₂ synthesis through promoting cAMP response element binding protein (CREB) and thereby CYP19A1 in KGN cells. Furthermore, ZNF217 negatively regulated TSP-1 in KGN cells while TSP-1 promoted claudin1 and inhibited nitric oxide (NO) in HUVECs and HAECs. Both of claudin1 and NO are responsible for the regulation of vascular permeability (VP). Therefore, we demonstrated that ZNF217 contributed to OHSS onset through promoting E₂ synthesis and the increase of VP. Moreover, the increased ZNF217 and decreased TSP-1 provided new targets for the prevention or treatment of OHSS in the future.

Comparison of the effects of letrozole and cabergoline on vascular permeability, ovarian diameter, ovarian tissue VEGF levels, and blood PEDF levels, in a rat model of ovarian hyperstimulation syndrome

OBJECTIVE

To evaluate the effects of letrozole and cabergoline in a rat model of ovarian hyperstimulation syndrome (OHSS).

STUDY DESIGN

In this prospective, controlled experimental study, the 28 female Wistar rats were divided into four subgroups (one non-stimulated control and three OHSS-positive groups: placebo, letrozole, and cabergoline). To induce OHSS, rats were injected with 10 IU of pregnant mare serum gonadotropin from day 29 to day 32 of life, followed by subcutaneous injection of 30 IU hCG on day 33. Letrozole rats received with a single dose of 0.1 mg/kg letrozole via oral gavage, on the hCG day. Cabergoline rats received with a single dose of 100 µg/kg cabergoline via oral gavage, on the hCG day. All animals were compared in terms of body weight, vascular permeability (VP), ovarian diameter, ovarian tissue VEGF expression (assessed via immunohistochemical staining), and blood pigment epithelium-derived growth factor (PEDF) levels.

RESULTS

The OHSS-positive placebo group (group 2) exhibited the highest VP, ovarian diameter, extent of VEGF staining, and lowest PEDF level, as expected. No significant difference was evident between the letrozole and cabergoline groups in terms of any of body weight; VP; PEDF level; ovarian diameter; or the staining intensity of, or percentage staining for, VEGF in ovarian tissues.

CONCLUSIONS

Letrozole and cabergoline were equally effective to prevent OHSS, reducing the ovarian diameter, VP, and PEDF and VEGF levels to similar extents.

Myo-inositol is a promising treatment for the prevention of ovarian hyperstimulation syndrome (OHSS): an animal study

PURPOSE

To evaluate the efficacy of myo-inositol (MI) pretreatment in OHSS.

METHODS

In this experimental OHSS rat model, 42 immature Wistar albino female rats were divided into 6 groups: (1) the control group, (2) the ovarian stimulation group, (3) the OHSS group, (4) the OHSS + Metformin group, (5) OHSS + MI group, (6) OHSS + Metformin + MI group. OHSS was established after treatment with metformin and myo-inositol for 14 days, in the meanwhile the treatment of metformin and myo-inositol was also continued. All animals were killed 48 h after hCG administration and were compared in terms of vascular permeability, ovarian weight and diameter, ovarian VEGF, COX-2 and PEDF expression (immunohistochemistry), serum PEDF and estradiol (E2) levels.

RESULTS

Vascular permeability, VEGF and COX-2 expressions were reduced in animals treated with MI and/or metformin. While PEDF expression was increased in the groups taking metformin, there was no difference in PEDF expression in the group taking MI and OHSS group. There was no significant difference in serum PEDF levels between groups. Blood E2 levels were decreased in groups treated with MI or metformin compared to the OHSS group.

CONCLUSIONS

Our data demonstrate that myo-inositol is effective in preventing OHSS, similar to metformin. Although the two drugs are thought to act through distinct mechanisms, there is no apparent benefit to co-treatment with both drugs in an animal model of OHSS. Administration of myo-inositol prior to IVF treatment may favor the control of ovulation induction. Further studies are necessary to elucidate the mechanism of action and further support our findings.

Dopamine agonist inhibits vascular endothelial growth factor protein production and secretion in granulosa cells

BACKGROUND

Dopamine receptor 2 agonists (D2-ags) inhibit vascular endothelial growth factor (VEGF) secretion in luteinized granulosa cells (LGCs) both in vitro and in vivo. However, the mechanism of D2 regulation of the VEGF/VEGF Receptor 2 (VEGFR-2) pathway remains to be elucidated. We sought to determine the effects of D2 signaling on VEGF transcription and translation in LGCs, with the expectation of identifying potential D2-ag-based therapies for ovarian hyperstimulation syndrome (OHSS).

FINDINGS

LGCs from egg donors were cultured with chorionic gonadotropin (hCG) in the presence of Actinomycin-D (ActD) or Brefeldin-A (BFA) to evaluate the effects of a D2-ag, cabergoline (Cb2), on VEGF secretion. The contribution of the conventional Gi/Go, Gz and AKT/β-Arrestin pathways in the VEGF regulation was assessed by adding pertussis toxin (PTX), phorbol 12-myristate 13-acetate (PMA), or wortmannin (WT). While Cb2 inhibited VEGF secretion by interfering with VEGF peptide translation and secretion, inhibition of conventional D2 transduction pathways did not reverse Cb2-mediated inhibition of VEGF secretion.

CONCLUSIONS

The effects of D2-ag on VEGF translation and secretion are mediated by D2 signaling pathways that have yet to be described. We found that D2-ag inhibits VEGF secretion at the post-transcriptional level, suggesting that D2-ag treatment should be combined with therapies that inhibit VEGF transcription, such as the employment of LH or GnRH for triggering ovulation, to improve the efficacy of OHSS prevention.

Revisiting ovarian hyper stimulation syndrome: Towards OHSS free clinic

A rapid development and application of assisted reproductive technologies (ARTs) and ovulation-induction drugs may lead to ovarian hyper stimulation syndrome (OHSS). Young age, low body mass index (BMI), polycystic ovarian syndrome (PCOS), previous OHSS, high follicle count, and elevated serum estradiol (E2) are the certain factors that predispose women to OHSS. Many strategies have been used to reduce or avoid OHSS. Use of human chorionic gonadotropin (hCG) increases ovarian vascular permeability and is responsible for activating the vascular endothelial growth factors (VEGF) pathway and thus the entire cascade, leading to symptomatic OHSS. Gonadotropin-releasing hormone (GnRH) agonists are used as a replacement for hCG for final oocyte maturation in antagonist cycles. Reducing or eliminating the use of hCG and use of GnRH agonist triggered GnRH antagonist cycles and cryopreservation of oocytes or embryos is the most promising approach in making OHSS free clinic a reality.