Ovarian Hyperstimulation Syndrome Rat Model Research Articles

Betaine Attenuates The Expression of Vasoactive Mediators and Histological Alterations Associated with Ovarian Hyperstimulation Syndrome in Rats.

Ovarian hyperstimulation syndrome (OHSS) is one female reproductive disorder that can occur after administration of injectable hormonal drugs to stimulate ovulation. Betaine (BET) is an intracellular biomolecule with anti-inflammatory and tissue protective effects. There is no information about its effects in an experimental model of OHSS. The current study aims to investigate the possible effects of BET on abnormal expressions of vasoconstrictor proteins and ovarian histological changes in an experimental OHSS rat model. In this experimental study, 30 adult female rats (two months old) were randomly divided into six groups (n=5 per group): i. Control, ii. OHSS [10 IU sc equine chorionic gonadotropin (eCG) for 4 days followed by 30 IU sc human chorionic gonadotropin (hCG) on the fifth day], iii. OHSS+BET (200 mg/kg/day, orally for seven days), iv. OHSS+Cabergoline (CAB, 100 mg/kg/day, orally for six days), v. BET, and vi. CAB. Expression levels of vascular endothelial growth factor (VEGF), cyclooxygenase-2 (COX-2), and blood levels of oestradiol (E2) and progesterone (P4) were measured at the end of the experiment. The ovaries were studied for histomorphological changes. Induction of OHSS altered tissue histology, including an increase in the number of corpora lutea and atretic follicles, and decreased the number of follicular reserves. In this group, we observed increased expressions of the VEGF and COX-2 proteins, and increased serum E2 and P4 levels. Administration of CAB and BET significantly attenuated all molecular and histological alterations observed in the OHSS animals. Our findings, for first time, indicate the beneficial effects of BET to reduce OHSS complications in patients by reducing the expressions of vasoactive proteins and improving changes to the ovarian tissues. The findings are similar to CAB and can be a new avenue for future research on BET.

Electroacupuncture Reduces Oocyte Number and Maintains Vascular Barrier Against Ovarian Hyperstimulation Syndrome by Regulating CD200

Ovarian hyperstimulation syndrome (OHSS) is a common complication caused by ovulatory stimulation therapy, which manifests as an increase in ovarian volume, an increase in the number of oocytes retrieved, and increased vascular permeability throughout the body and especially in ovarian tissue. In our previous study, we found that electroacupuncture (EA) could prevent the progression of OHSS, by mainly affecting ovary. However, the specific molecules and the mechanism of this process were still unknown. In order to explore the underlying mechanism, OHSS rat model was established and EA treatment was performed, which was followed by proteomic analysis of ovaries. Results showed a significant increase in the expression level of CD200 in the ovaries of OHSS group treated with EA than those of OHSS group. Clinical data showed that the level of CD200 in follicular fluid was negatively correlated with the number of oocytes retrieved and serum E2 level. Further in vitro experiments showed a concentration-dependent role of human chorionic gonadotropin (hCG) in reducing CD200 and CD200R levels, and increasing inflammatory cytokine levels in cultured KGN cells. In human umbilical vein endothelial cells (HUVECs), the vascular barrier function was improved by CM (cultural medium from KGN cell) which treated with CD200Fc (CD200R agonist). Meanwhile, the results of in vivo experiments indicated that EA reduced the number of ovarian corpora lutea, decreased inflammatory response, and improved the vascular barrier function by increasing the expression of CD200 and CD200R in rat ovaries. These findings suggest that EA treatment may reduce oocyte number and maintain vascular barrier against OHSS through ovarian anti-inflammatory response mediated by CD200. Therefore, this study is the first to identify CD200 as a main of EA in the ovary and elucidate the possible mechanism of EA on preventing and treating OHSS, which provide a scientific basis for CD200 as an effector and indicator in EA treatment.

Platelet-derived growth factor B restores vascular barrier integrity and diminishes permeability in ovarian hyperstimulation syndrome.

Although advances in the prediction and management of ovarian hyperstimulation syndrome (OHSS) have been introduced, complete prevention is not yet possible. Previously, we and other authors have shown that vascular endothelial growth factor, angiopoietins (ANGPTs) and sphingosine-1-phosphate are involved in OHSS etiology. In addition, we have demonstrated that ovarian protein levels of platelet-derived growth factor (PDGF) ligands -B and -D decrease in an OHSS rat model, whilst PDGFR-β and ANGPT2 remain unchanged. In the present work, we investigated the role of PDGF-B in OHSS by evaluating ligand protein levels in follicular fluid (FF) from women at risk of developing OHSS and by using an immature rat model of OHSS. We demonstrated that PDGF-B and PDGF-D are lower in FF from women at risk of developing OHSS compared to control patients (P < 0.05). In the OHSS rat model, PDGF-B (0.5 µg/ovary) administration decreased ovarian weight (P < 0.05), reduced serum progesterone (P < 0.05) and lowered the percentage of cysts (P < 0.05), compared to untreated OHSS rats, but had no effect on the proportion of follicles or corpora lutea (CL). PDGF-B treatment also restored the expression of steroidogenic acute regulatory protein (P < 0.05) and P450 cholesterol side-chain cleavage enzyme (P < 0.01) to control levels. In addition, PDGF-B increased the peri-endothelial cell area in CL and cystic structures, and reduced vascular permeability compared to untreated OHSS ovaries. Lastly, PDGF-B increased the levels of junction proteins claudin-5 (P < 0.05), occludin (P < 0.05) and β-catenin (P < 0.05), while boosting the extracellular deposition of collagen IV surrounding the ovarian vasculature (PP < 0.01), compared to OHSS alone. In conclusion, our findings indicate that PDGF-B could be another crucial mediator in the onset and development of OHSS, which may lead to the development of novel prediction markers and therapeutic strategies.

In vivo intrabursal administration of bioactive lipid sphingosine-1-phosphate enhances vascular integrity in a rat model of ovarian hyperstimulation syndrome.

Can the bioactive lipid sphingosine-1 phosphate (S1P) act as an endothelial barrier-enhancing molecule and, in turn, restore the vascular integrity and homoeostasis in a rat model of ovarian hyperstimulation syndrome (OHSS). In vivo administration of S1P may prevent the early onset of OHSS and decrease its severity. Although advances in the prediction and treatment of OHSS have been made, complete prevention has not been possible yet. S1P in follicular fluid from women at risk of developing OHSS are lower in comparison from women who are not at such risk and administration of S1P in an OHSS rat model decreases ovarian capillary permeability. We used an animal model that develops OHSS in immature Sprague-Dawley rats. The rats were randomly divided into three groups: the control group, which was injected with 10 IU of pregnant mare's serum gonadotropin (PMSG), and 10 IU ofhCG 48 h later; the OHSS group, which was injected with excessive doses of PMSG (50 IU/day) for four consecutive days, followed by hCG; and the OHSS + S1P group, which was injected with the same doses of PMSG and hCG as the OHSS group and then treated with 5 μl S1P (1 mM) under the bursa of both ovaries, whereas the other groups of animals received the S1P vehicle. Rats were killed by decapitation 48 h after the hCG injection for ovary, endometrium and blood collection. The ovaries were weighed and then used for subsequent assays, while the serum was used for hormone assays. One of the ovaries from each rat (n = 6) was used for Western immunoblot and the other for immunohistochemical analysis. Statistical comparisons between groups were carried out. S1P administration reduced the ovarian weight (P < 0.05), and decreased the concentration of serum progesterone in the OHSS group compared to the OHSS group without treatment (P < 0.001). The percentage of antral follicles in the OHSS group was lower than that in the control group. S1P increased the percentage of antral follicles (P < 0.05) and decreased the percentage of corpora lutea (P < 0.01) and cystic structures in the OHSS group (P < 0.05). S1P had no effect on the expression levels of the enzymes 3β-hydroxysteroid dehydrogenase (3βHSD) or cholesterol side-chain cleavage enzyme (P450scc), but reduced the levels of steroidogenic acute regulatory protein (StAR) in OHSS rat ovaries (P < 0.05). S1P decreased the endothelial (P < 0.05) and periendothelial (P < 0.01) cell area in OHSS rat ovaries. S1P restored the levels of N-cadherin and VE-cadherin proteins to control values. Furthermore, S1P enhanced the levels of claudin-5, occludin (P < 0.05) and sphingosine-1-phosphate receptor 1 (S1PR1) in OHSS (P < 0.01). In addition, no histological differences were found in endometrium between OHSS and S1P-treated OHSS animals. The results of this study were generated from an in vivo OHSS experimental model, which has been used by several authors and our group due to the similarity between the rat and human angiogenic systems. Further studies in patients will be needed to evaluate the effects of S1P in the pathogenesis of OHSS. These findings concern the pathophysiological importance of S1P in OHSS. More studies on the regulation of endothelial cell barrier function by S1P in reproductive pathological processes and its therapeutic application are required. N/A. This work was supported by grants from ANPCyT (PICT 2012-897), CONICET (PIP 5471), Roemmers and Baron Foundations, Argentina. The authors declare no conflicts of interest.

The combination of Everolimus with Verapamil reduces ovarian weight and vascular permeability on ovarian hyperstimulation syndrome: a preclinical experimental randomized controlled study

The efficacy of pathways inhibition and the combined effect of Everolimus (mTOR inhibitor) and Verapamil (CYP3A inhibitor) in ovarian hyperstimulation syndrome (OHSS) need to be tested. Therefore, the impact of a leucotriene receptor antagonist, an anticoagulant, a GnRH antagonist as well as Everolimus plus Verapamil (at various doses and days of administration) on an OHSS rat model was tested. Sixty three female Wistar rats were randomly divided into seven groups. The control group received saline, while the OHSS group received rec-FSH for four consecutive days. The other five groups received rec-FSH for four days and Montelukast daily, Heparin daily, GnRH antagonist daily, Everolimus plus Verapamil in the last two days (half days group) and Everolimus plus Verapamil (half dose group) daily, respectively. All groups received also hCG at the fifth day. Significantly reduced ovarian weight was observed in the Everolimus plus Verapamil groups (half days and half-dose groups) and the Montelukast group compared to the OHSS group (p = 0.001 and p = 0.001, respectively). The vascular permeability was significantly reduced in the Everolimus plus Verapamil group (half dose group) and the GnRH antagonist group compared to the OHSS group (p < 0.001 and p = 0.011, respectively). However, estradiol and progesterone levels did not differ significantly between the groups. Studying the inhibition of different pathways, we concluded that the co-administration of Everolimus and Verapamil (at half dose) is beneficial for reducing ovarian weight and vascular permeability in an OHSS animal model.

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

PurposeTo evaluate the efficacy of myo-inositol (MI) pretreatment in OHSS.MethodsIn 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.ResultsVascular 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.ConclusionsOur 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.

Local VEGF inhibition prevents ovarian alterations associated with ovarian hyperstimulation syndrome

The relationship between human chorionic gonadotropin and ovarian hyperstimulation syndrome (OHSS) is partially mediated by vascular endothelial growth factor A (VEGF). The aim of this study was to investigate the effects of VEGF inhibition on the development of corpora lutea (CL) and cystic structures, steroidogenesis, apoptosis, cell proliferation, endothelial cell area, VEGF receptors (KDR and Flt-1), claudin-5 and occludin levels in ovaries from an OHSS rat model. The VEGF inhibitor used (VEGF receptor-1 (FLT-1)/Fc chimera, TRAP) decreased the concentrations of progesterone and estradiol as well as the percentage of CL and cystic structures in OHSS rats, and increased apoptosis in CL. Endothelial cell area in CL and KDR expression and its phosphorylation were increased, whereas claudin-5 and occludin levels were decreased in the OHSS compared to the control TRAP reversed these parameters. Our findings indicate that VEGF inhibition prevents the early onset of OHSS and decreases its severity in rats.

Involvement of the ANGPTs/Tie-2 system in ovarian hyperstimulation syndrome (OHSS)

Ovarian hyperstimulation syndrome (OHSS) is a disorder associated with ovarian stimulation. OHSS features are ovarian enlargement with fluid shifting to the third space. Disturbances in the vasculature are considered the main changes that lead to OHSS. Our aim was to analyze the levels of angiopoietins 1 and 2 (ANGPT1 and 2) and their soluble and membrane receptors (s/mTie-2) in follicular fluid (FF) and in granulosa-lutein cells culture (GLCs) from women at risk of developing OHSS. We also evaluated the effect of ANGPT1 on endothelial cell migration. In ovaries from an OHSS rat model, we analyzed the protein concentration of ANGPTs, their mTie-2 receptor, and platelet-derived growth factor PDGF-B, -D and PDGFR-β. ANGPT1 levels were increased in both FF and GLCs from women at risk of OHSS. Incubation of these FF with an ANGPT1 neutralizing antibody decreased endothelial cell migration. In the ovaries of OHSS rat model, mTie-2 protein levels increased and PDGF-B and -D decreased. In summary, these results suggest that ANGPT1 could be another mediator in the development of OHSS.

Etiology of OHSS and use of dopamine agonists

Vascular endothelial growth factor is the factor that causes increased capillary permeability and therefore the most serious manifestations of ovarian hyperstimulation syndrome. Dopamine agonists can both prevent and treat ovarian hyperstimulation syndrome by blocking expression of the vascular endothelial growth factor receptor.

Administration of a gonadotropin-releasing hormone agonist affects corpus luteum vascular stability and development and induces luteal apoptosis in a rat model of ovarian hyperstimulation syndrome

Ovarian hyperstimulation syndrome (OHSS) is a complication of ovarian stimulation with gonadotropins followed by the administration of human chorionic gonadotropin (hCG) to trigger the final steps of oocyte maturation. Gonadotropin-releasing hormone (GnRH) analogs are thought to be effective in preventing this complication and a clinical trial has found a lower incidence of OHSS in patients treated with these molecules. Our aim was to analyze the in vivo effect of a GnRH-I agonist on corpus luteum development and regression, ANGPT-1, ANGPT-2 and Tie-2 protein expression and luteal blood vessel stabilization, the expression of the steroidogenic acute regulatory protein (StAR) and the cytochrome P450 side-chain cleavage enzyme (P450scc) and cell proliferation, in ovaries from an OHSS rat model. To this end immature female Sprague-Dawley rats were hyperstimulated and treated with a GnRH-I agonist from the start of pregnant mare serum gonadotropin (PMSG) administration until the day of hCG injection for 5 consecutive days. Blood and tissue samples were collected 48h after hCG injection. Vascular endothelial growth factor VEGF levels were evaluated in the peritoneal fluid by ELISA. Serum progesterone and estradiol were measured by RIA. Histological features of sectioned ovaries were assessed in hematoxylin and eosin (H&E) stained slides. Luteal blood vessel stability, cell proliferation and apoptosis were assessed by immunohistochemistry for SMCA, PCNA, and TUNEL, respectively. P450scc, StAR, FLK-1, ANGPT-1, ANGPT-2, Tie-2 and PCNA protein levels were evaluated by Western blot from dissected corpora lutea (CL). The treatment with the GnRH-I agonist significantly decreased serum progesterone and estradiol levels as well as P450scc and StAR protein expression in the untreated OHSS group. In addition, the agonist significantly decreased the number of CL in the OHSS group, as compared with the untreated OHSS group. In the OHSS group, the area of periendothelial cells in the CL was larger than that of the control group. However, the treatment with the GnRH-I agonist significantly reduced the area of periendothelial cells in the CL in the OHSS group. The luteal levels of ANGPT-1 and its receptor Tie-2 significantly increased in the OHSS group when compared with the control group. Conversely, the administration of the GnRH-I agonist significantly decreased the levels of these factors in the CL from the OHSS group, as compared with the untreated OHSS group. In addition, the treatment with the GnRH-I agonist reduced the diameter of CL and decreased CL cell proliferation as compared with that observed in the untreated OHSS group. Finally, the GnRH-I agonist increased apoptosis in the CL from the OHSS group. In conclusion, these results show that GnRH-I agonist exerts diverse actions on the CL from a rat OHSS model. The decrease in P450scc, StAR, ANGPT-1 and Tie-2 expression, blood vessel stability and luteal proliferation leads to CL regression in the ovaries from OHSS rats. Moreover, our results suggest that the downregulation of ANGPT-1 and its receptor is a possible mechanism whereby GnRH-I agonists could prevent early OHSS.

Effects of gonadotropin-releasing hormone antagonists on the expression of vascular endothelial growth factor and its receptors in a rat model of ovarian hyperstimulation syndrome

Ovarian hyperstimulation syndrome (OHSS) is one of the most life-threatening complications of assisted reproduction treatments. Gonadotropin-releasing hormone antagonists (GnRHanta) are thought to be effective in preventing this complication, and some clinical trials have found lower incidences of OHSS in patients treated with GnRHanta. Our aim was to investigate the effects of GnRHanta on vascular permeability and the expression of vascular endothelial growth factor (VEGF) and its receptors in a rat model of OHSS. An immature early OHSS rat model was established. Three ovarian stimulation protocols were used: pregnant mare serum gonadotropin/human chorionic gonadotropin (hCG) alone, with a GnRHanta, or with a gonadotropin-releasing hormone agonists (GnRHa). Blood and tissue samples were collected at 48 hours after hCG administration. Vascular permeability was evaluated by measuring the Evans-Blue content of extravasated peritoneal fluids. The expression of VEGF and its receptors, including flt-1 and KDR, were detected by reverse transcriptase-polymerase chain reaction and Western blotting. Treatment with both a GnRHanta and a GnRHa resulted in significant reductions in serum estradiol and peritoneal vascular permeability, as well as decreased ovarian expression of VEGF and its two receptors. However, GnRHanta treatment caused a greater reduction in serum estradiol concentrations, and in VEGF receptor mRNA expression than GnRHa. There were no significant reductions in the expression of VEGF or its receptors in extra-ovarian tissues, including the liver, lungs and peritoneum. Our results reveal that GnRHanta are more potent than GnRHa in preventing early OHSS through down-regulation of the expression of VEGF and its receptors in hyperstimulated ovaries.

Low-Dose Dopamine Agonist Administration Blocks Vascular Endothelial Growth Factor (VEGF)-Mediated Vascular Hyperpermeability without Altering VEGF Receptor 2-Dependent Luteal Angiogenesis in a Rat Ovarian Hyperstimulation Model

No specific treatment is available for ovarian hyperstimulation syndrome (OHSS), the most important complication in infertile women treated with gonadotropins. OHSS is caused by increased vascular permeability (VP) through ovarian hypersecretion of vascular endothelial growth factor (VEGF)-activating VEGF receptor 2 (VEGFR-2). We previously demonstrated in an OHSS rodent model that increased VP was prevented by inactivating VEGFR-2 with a receptor antagonist (SU5416). However, due to its toxicity (thromboembolism) and disruption of VEGFR-2-dependent angiogenic processes critical for pregnancy, this kind of compound cannot be used clinically to prevent OHSS. Dopamine receptor 2 (Dp-r2) agonists, used in the treatment of human hyperprolactinemia including pregnancy, inhibit VEGFR-2-dependent VP and angiogenesis when administered at high doses in animal cancer models. To test whether VEGFR-2-dependent VP and angiogenesis could be segregated in a dose-dependent fashion with the Dp-r2 agonist cabergoline, a well-established OHSS rat model supplemented with prolactin was used. A 100 microg/kg low-dose Dp-r2 agonist cabergoline reversed VEGFR-2-dependent VP without affecting luteal angiogenesis through partial inhibition of ovarian VEGFR-2 phosphorylation levels. No luteolytic effects (serum progesterone levels and luteal apoptosis unaffected) were observed. Cabergoline administration also did not affect VEGF/VEGFR-2 ovarian mRNA levels. Results in the animal model and the safe clinical profile of Dp-r2 agonists encouraged us to administer cabergoline to oocyte donors at high risk for developing the syndrome. Prophylactic administration of cabergoline (5-10 microg/kg x d) decreased the occurrence of OHSS from 65% (controls) to 25% (treatment). Therefore, a specific, safe treatment for OHSS is now available.