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:

Effect of ondansetron for preventing of ovarian hyperstimulation syndrome: in an experimental rat model

Objective: Ovarian hyperstimulation syndrome is an iatrogenic condition that occurs in the treatment of infertility. There is no specific treatment available for OHSS. Cabergoline is a dopamine receptor 2 agonist and VEGF-VEGF2 receptor antagonist . Recently, cabergoline has been widely used to prevent the development of OHSS and reduce its severity Serotonin is known as a neurotransmitter and thought to have a role in the mechanism of angiogenesis and in signaling in endothelial cells. Serotonin is said to have similar effects to VEGF . Ondansetron is Selective Serotonin (5-HT3) Receptor Antagonist . It works by blocking the action of serotonin, a natural substance that may cause nausea and vomiting. In the clinical practice today, there is no choice other than cabergoline, to prevent occurrence and reduce severity of OHSS, and sometimes its effects are limited. Methods: In our study, we compared the effect of cabergoline and ondansetron. 32 immature rats were used and the OHSS model was created. Parameters such as hematocrit value , ovarian size, the number of follicles in the ovary, endometrial capillary congestion and thickness values were evaluated and compared. Results: As a result, in our study, it was seen that ondansetron was effective on OHSS in many parameters. It is thought to be as effective as cabergoline. When we look at the literature, this is the first study in which ondansetron was evaluated for this purpose. It would be good to show this effect of ondansetron with other studies.

The use of gonadotropin-releasing hormone antagonist post-ovulation trigger in ovarian hyperstimulation syndrome

The purpose of this paper is to assimilate all data pertaining to the use of gonadotropin-releasing hormone (GnRH) antagonists in in vitro fertilization cycles after ovulation trigger to reduce the symptoms of ovarian hyperstimulation syndrome (OHSS). A systematic review of the literature was performed to identify all studies performed on the use of a GnRH antagonist in IVF cycle post-ovulation trigger with patients at high risk for OHSS. Ten studies were identified and reviewed. Descriptions of the studies and their individual results are presented in the following manuscript. Due to significant heterogeneity among the studies, it was not possible to perform a group analysis. The use of GnRH antagonists post-ovulation trigger for treatment of OHSS has been considered for almost 20 years, though research into its use is sparse. Definitive conclusions and recommendations cannot be made at this time, though preliminary data from these trials demonstrate the potential for GnRH antagonists to play a role in the treatment of OHSS in certain patient populations.

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.

Prevention of ovarian hyperstimulation syndrome in a rat model: comparison of the efficacy of tocilizumab with that of ranibizumab, cabergoline, and a gonadotropin-releasing hormone antagonist

The aim of the study is to investigate the effects of the interleukin-6 (IL-6) blocker tocilizumab in a hyperstimulated rat model and compare it with ranibizumab, a gonadotropin-releasing hormone antagonist (GnRHA), and cabergoline. Forty-seven rats were randomly divided into the following seven groups: Group 1: OHS; Group 2: OHS+ GnRHA; Group 3: OHS + ranibizumab; Group 4: OHS + cabergoline; Group 5: OHS + low-dose tocilizumab (TL); Group 6: OHS + high-dose tocilizumab (TH); Group 7: sham. Ovarian weight was significantly lower only in the ranibizumab group than in the OHS group. Estrogen levels were significantly lower in the GnRHA group than in the OHS and the treatment groups. Progesterone levels were significantly lower in the ranibizumab, cabergoline, and TL groups than in the OHS group. Among the treatment groups, corpus luteum counts were lower than in the OHS group. Corpus luteum counts were lowest in the tocilizumab groups. IL-6 intensity was lower in all treatment groups than in the OHS group. In the ranibizumab group IL-6 intensity was the lowest. The TL group did not significantly differ from the GnRHA and cabergoline groups regarding IL-6 expression. Ovarian VEGF expression was significantly lower in all treatment groups. For the TL, ranibizumab, and cabergoline groups VEGF intensity was similar. Tocilizumab may be a new strategy for preventing ovarian hyperstimulation syndrome by inhibition of IL-6.

A potential novel strategy, inhibition of vasopressin-induced VEGF secretion by relcovaptan, for decreasing the incidence of ovarian hyperstimulation syndrome in the hyperstimulated rat model

OBJECTIVE

To investigate the effects of V1A receptor antagonist through inhibition of vasopressin-induced VEGF secretion in an experimental model.

STUDY DESIGN

Thirty rats were randomly divided into five groups. Four groups were given 10IU pregnant mare serum gonadotropin/day (sc) at 8:00-8:30am on days 22-25 of life. They were administered 30IU hCG at 8:00-8:30am on day 26 of life. On days 26 and 27 of life at 8:00am and 4:00pm, (ip) per animal, 50μg/kg/day GnRH antagonist in the GnRH antagonist group, 0.3mg relcovaptan in the high dose relcovaptan group, and 0.15mg relcovaptan in the low dose relcovaptan group were administered. The control group was given the same dosage of 0.9% saline solution (ip) on days 22-26 day of life. The main outcomes were weight gain, ovarian weights, peritoneal fluid VEGF values, corpus luteum count, and atretic follicle count.

RESULTS

Weight gain was highest in the OHSS group; it was almost twice as much in the OHSS group than it was in the control group. Ovarian weights were significantly lower in all treatment groups (p=0.03). There was no statistically significant difference in ovarian weights between the GnRH antagonist and relcovaptan groups (p=0.176). The evaluation of peritoneal fluid VEGF-A levels revealed statistically significant differences between levels in the treatment groups and in the OHSS group (p=0.005). Atretic follicle count in the OHSS group was significantly lower (p=0.048). In all treatment groups, CL counts were prominently lower than they were in the OHSS group (p=0.002).

CONCLUSION

Relcovaptan may be a novel strategy for decreasing risk of OHSS by inhibition of vasopressin-induced VEGF secretion through V1A receptor antagonist.

Comparison of bevacizumab and cabergoline in the treatment of ovarian hyperstimulation syndrome in a rat model

The aim of this study is to investigate the effects of bevacizumab in a rat model of ovarian hyperstimulation syndrome (OHSS) and compare with cabergoline. The study was performed with 24 rats in four main groups (one non-stimulated control and three OHSS treatment groups; bevacizumab, cabergoline and placebo). The rats were randomly assigned to four experimental groups (six rats per group). Efficacy of treatment was assessed on 29th day by measuring weight gain, number of eggs, presence of ascites and ovarian weight. Peritoneal fluid levels of vascular endothelial growth factor (VEGF) were measured using an enzyme-linked immunosorbent assay. Ovarian weights were significantly higher in the OHSS groups than the control group. Ovarian weights in OHSS placebo group were found to be higher than those in OHSS-treatment groups (p = 0.002). VEGF levels were found increased in the OHSS-placebo group compared with the control group (p < 0.05). This increase was not seen in the OHSS groups treated with either bevacizumab or cabergoline. We demonstrate in this study that bevacizumab can lower VEGF production and ovarian weight in rats treated with gonadotropins.

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.