Variations in serum vascular endothelial growth factor binding profiles and the development of ovarian hyperstimulation syndrome

Effect of varying doses of tamoxifen on ovarian histopathology, serum VEGF, and endothelin 1 levels in ovarian hyperstimulation syndrome: an experimental study

OBJECTIVE

To examine the effects of low-to-high doses of tamoxifen on ovarian histopathology, serum VEGF, and endothelin 1 levels in ovarian hyperstimulation syndrome (OHSS) in an experimental setting.

MATERIALS AND METHODS

A total of 20 female Wistar albino rats, 22 days of age, were randomly divided into four groups. Follicle-stimulating hormone 10 IU was administered subcutaneously in 15 rats on 4 consecutive days, with OHSS induction on day 5 by 30 IU of human chorionic gonadotropin. Group 1 (n=5) comprised 35-day-old control rats, group 2 (n=5) 35-day-old OHSS rats, group 3 (n=5) 27-day-old OHSS rats receiving 1 mg/kg of oral tamoxifen for 7 days, group 4 (n=5) 27-day-old OHSS rats receiving 3 mg/kg of oral tamoxifen for 7 days. All rats were decapitated on day 35. Serum VEGF, endothelin 1, and ovarian follicular reserve were assessed in all rats. Kruskal-Wallis variance analysis and the Mann-Whitney U-test were used for statistical comparisons. A Bonferroni correction was performed to control the inflation of significance, with a significance level set at a P-value of less than 0.025.

RESULTS

Despite higher serum VEGF, endothelin 1, follicular reserve, and angiogenesis and fibrosis of the corpus luteum in the OHSS group compared to controls, these differences were not significant (P>0.025, Mann-Whitney U-test). There was a significant reduction in the ovarian follicular reserve in tamoxifen groups compared to controls (P<0.025, Mann-Whitney U-test), while angiogenesis of the corpus luteum, number of atretic follicles, fibrosis, and serum VEGF were significantly higher in rats receiving tamoxifen (P<0.025, Mann-Whitney U-test). Also, significantly lower follicular reserve and fibrosis were observed among rats in the low-dose tamoxifen group in comparison with rats in the high-dose tamoxifen group (P<0.025, Mann-Whitney U-test). No groups had a significant change in endothelin 1 levels (P>0.025, Mann-Whitney U-test).

CONCLUSION

Tamoxifen 1 g and 3 g resulted in a dose-dependent increase in VEGF and endothelin 1 levels, and ovarian follicle reserves were significantly reduced in our experimental model.

Vascular endothelial growth factor levels in serum and plasma from patients undergoing controlled ovarian hyperstimulation for IVF

BACKGROUND

Vascular endothelial growth factor (VEGF) has been investigated as a marker of ovarian response to controlled ovarian hyperstimulation and as a predictor of ovarian hyperstimulation syndrome (OHSS) in IVF cycles. In most studies, serum has been used for circulating VEGF concentration measurement, but it has been suggested that plasma is the preferred medium to measure VEGF levels because of the potential contribution of VEGF released from platelets during blood clotting. This study investigated VEGF concentrations in paired serum and plasma samples from patients undergoing controlled ovarian hyperstimulation for IVF.

METHODS

Serum and plasma VEGF levels, as well as the number of platelets, were measured in 30 IVF patients who comprised three study groups delineated according to the estradiol (E(2)) serum concentration reached on the day of HCG administration: 10 patients having low E(2) serum levels (<1500 pg/ml, group L), 10 patients having intermediate E(2) serum levels (1500-3000 pg/ml, group I) and 10 patients having high E(2) serum levels (>3000 pg/ml, group H).

RESULTS

There was a statistically significant correlation between plasma and serum VEGF levels (rho = 0.61; P < 0.005) for the entire population studied, although serum values were higher by a factor of approximately 6-fold. No significant correlation was found between peripheral blood VEGF concentrations and serum E(2) or follicle number on HCG day or the number of oocytes collected. Similarly, paired serum and plasma VEGF measurements did not correlate with platelet count.

CONCLUSIONS

Serum and plasma VEGF concentrations are strongly correlated in paired samples from infertile patients undergoing controlled ovarian hyperstimulation. However, neither serum nor plasma VEGF levels were correlated with parameters associated with ovarian follicular activity. Peripheral blood VEGF levels were not correlated with platelet count.

Immunohistochemical detection of transforming growth factor-α, epidermal growth factor, and vascular endothelial growth factor expression in hyperstimulated rat ovary

OBJECTIVE

The aim of the present study is to figure out the immunohistochemical expression of transforming growth factor-alpha (TGF-alpha), epidermal growth factor (EGF), and vascular endothelial growth factor (VEGF) in hyperstimulated rat ovaries.

METHODS

Twenty Wistar-Albino adult female rats (250-300 g) were taken into the study. The animals were randomly divided into two groups, each containing 10 rats: (i) stimulation group and (ii) control group. In the stimulation group, a stimulation regimen was administered to induce follicular maturity and ovarian hyperstimulation syndrome (OHSS) at the end using a 30-IU follicle-stimulating hormone that was administered subcutaneously for 4 consecutive days, followed by a 30-IU human chorionic gonadotropin on day 5 to induce ovulation. The rats, in the control group, received 0.2 ml of 0.9% NaCl for 5 consecutive days to mimic the conditions of the study animals. At the end of the treatment period, all rats underwent ovariectomy and the sections of ovaries were stained for the TGF-alpha, EGF, and VEGF.

RESULTS

The expression of TGF-alpha, EGF, and VEGF in the endothelium, the stroma, the granulosa cells, and the corpus luteum was found to be significantly higher in the stimulated group, compared to that in the control group ( p < 0.05).

CONCLUSION

TGF-alpha, EGF, and VEGF are found to have increased in the hyperstimulated ovaries and this finding seems to be involved in the OHSS pathogenesis.

Estrogen-induced abnormally high cystic fibrosis transmembrane conductance regulator expression results in ovarian hyperstimulation syndrome

Ovarian hyperstimulation syndrome (OHSS) remains one of the most life-threatening and potentially fatal complications of assisted reproduction treatments, arising from excessive stimulation of the ovaries by exogenous gonadotropins administrated during in vitro fertilization procedures, which is characterized by massive fluid shift and accumulation in the peritoneal cavity and other organs, including the lungs and the reproductive tract. The pathogenesis of OHSS remains obscure, and no definitive treatments are currently available. Using RT-PCR, Western blot, and electrophysiological techniques we show that cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP-activated chloride channel expressed in many epithelia, is involved in the pathogenesis of OHSS. Upon ovarian hyperstimulation, rats develop OHSS symptoms, with up-regulated CFTR expression and enhanced CFTR channel activity, which can also be mimicked by administration of estrogen, but not progesterone, alone in ovariectomized rats. Administration of progesterone that suppresses CFTR expression or antiserum against CFTR to OHSS animals results in alleviation of the symptoms. Furthermore, ovarian hyperstimulation does not induce detectable OHSS symptoms in CFTR mutant mice. These findings confirm a critical role of CFTR in the pathogenesis of OHSS and may provide grounds for better assisted reproduction treatment strategy to reduce the risk of OHSS and improve in vitro fertilization outcome.

Effect of angiotensin-converting enzyme-inhibiting therapy on the expression of vascular endothelial growth factor in hyperstimulated rat ovary

OBJECTIVE

To determine the effect of angiotensin-converting enzyme-inhibiting therapy on the expression of vascular endothelial growth factor (VEGF) in the hyperstimulated rat ovary.

DESIGN

Experimental study.

SETTING

University animal research laboratory.

ANIMAL(S)

Thirty Wistar albino adult female rats were studied; 20 rats were stimulated with gonadotropins (groups 1 and 2), and 10 were controls (group 3). Ten of the stimulated rats received additional treatment with enalapril (group 2).

INTERVENTION(S)

At the end of the treatment period, rat ovaries were subjected to immunohistochemical staining with anti-VEGF antibodies.

MAIN OUTCOME MEASURE(S)

VEGF staining intensity was graded semiquantitatively, and the H-score was calculated by light microscopic examination of the groups.

RESULT(S)

VEGF expression was found to be significantly higher in the endothelium and stroma in groups 1 and 2 compared with group 3. Although VEGF immunoreactivity was lower in the stimulation regimen plus enalapril group compared with the stimulation regimen-only group, the difference was insignificant.

CONCLUSION(S)

Enalapril does not seem to have a significant effect on VEGF expression in the hyperstimulated rat ovary. Because angiotensin II exerts its multiple actions via specific receptors, there may be other factors, such as a receptor blockade, that contribute to the VEGF expression.

RETRACTED: Evidence of a pluripotent human embryonic stem cell line derived from a cloned blastocyst

Somatic cell nuclear transfer (SCNT) technology has recently been used to generate animals with a common genetic composition. In this study, we report the derivation of a pluripotent embryonic stem (ES) cell line (SCNT-hES-1) from a cloned human blastocyst. The SCNT-hES-1 cells displayed typical ES cell morphology and cell surface markers and were capable of differentiating into embryoid bodies in vitro and of forming teratomas in vivo containing cell derivatives from all three embryonic germ layers in severe combined immunodeficient mice. After continuous proliferation for more than 70 passages, SCNT-hES-1 cells maintained normal karyotypes and were genetically identical to the somatic nuclear donor cells. Although we cannot completely exclude the possibility that the cells had a parthenogenetic origin, imprinting analyses support a SCNT origin of the derived human ES cells.

New concepts in the understanding of the ovarian hyperstimulation syndrome

PURPOSE OF REVIEW

In this review we will evaluate the recent developments in the pathophysiology of the ovarian hyperstimulation syndrome, with special emphasis on mediators of human chorionic gonadotropin action.

RECENT FINDINGS

From all the different molecules investigated, it seems that vascular endothelial growth factor is the key mediator of human chorionic gonadotropin action on the vascular tree. Recent data show that although absolute serum vascular endothelial growth factor values are useless in predicting the occurrence of ovarian hyperstimulation syndrome, individual variations in binding profiles may account for clinical differences. It has been shown that vascular endothelial growth factor is produced, expressed and secreted in the ovary and that it mediates vascular permeability in response to human chorionic gonadotropin in a time-dependent fashion. This effect may be blocked by a synthetic compound (SU5416) developed to inhibit its high-affinity receptor, kinase domain containing receptor signaling in different cancers by avoiding the initial phosphorylation of vascular endothelial growth factor receptor-2.

SUMMARY

Vascular endothelial growth factor is a promising molecule in the understanding of ovarian hyperstimulation syndrome. Future treatments should be directed to modulate or inhibit its action on the vascular wall.