Fiorella Miceli

Context: Ghrelin, well-known modulator of food intake and energy balance, is a rather ubiquitous peptide involved in several endocrine and nonendocrine actions. A possible as-yet-unknown role for ghrelin in modulating luteal function has been suggested because both ghrelin and its receptor (GRLN-R) have been immunohistochemically detected in human corpus luteum. Objective: We first investigated GRLN-R mRNA expression in midluteal phase human luteal cells. Ghrelin effect on basal and human chorionic gonadotropin (hCG)-stimulated progesterone (P) release was then analyzed. Finally, we investigated whether ghrelin could affect luteal release of vascular endothelial growth factor (VEGF), prostaglandin (PG) E₂, both luteotropic factors, and PGF_2α, luteolytic modulator. Ghrelin effect on both basal and hypoxia-stimulated VEGF luteal expression was analyzed. Methods: Human luteal cells were incubated for 24 h with ghrelin (10⁻¹³ to 10⁻⁷m) or hCG (100 ng/ml) or CoCl₂ (10 μm), chemical hypoxia, or with hCG or CoCl₂ in combination with ghrelin. Both GRLN-R mRNA and VEGF mRNA were evaluated by real-time RT-PCR. PGs and P release was assayed by RIA, whereas VEGF release by ELISA. Results: GRLN-R mRNA expression was demonstrated in human luteal cells. Both basal and hCG-stimulated P release was significantly decreased by ghrelin, which was able to reduce PGE₂ and increase PGF_2α luteal release. Both basal and hypoxia-stimulated VEGF release was significantly decreased by ghrelin, which did not affect VEGF mRNA luteal expression. Conclusions: The present in vitro study provides the first evidence of a direct inhibitory influence of ghrelin on human luteal function.

Vascular endothelial growth factor (VEGF) is essential for normal luteal development and function, but little is still known about the regulation of its production by human midluteal phase luteal cells. We investigated whether human chorionic gonadotropin (hCG) or local factors, including chemical hypoxia, IGF-I and IGF-II, prostaglandin (PG)E(2), and PGF(2alpha) prevail in modulating VEGF mRNA and protein production in human midluteal phase luteal cells. The effect of progesterone (P) on luteal VEGF mRNA expression and protein secretion was also evaluated. Finally, we investigated whether VEGF could directly affect luteal P secretion. In human midluteal phase luteal cells, VEGF mRNA expression was evaluated by semiquantitative RT-PCR, whereas VEGF and P release was evaluated by ELISA and RIA, respectively. hCG was unable to significantly affect luteal VEGF mRNA and protein synthesis, which in turn was significantly increased by both chemical hypoxia and IGFs. Conversely, VEGF mRNA and protein production was reduced by PGs and P. Finally, VEGF did not affect P luteal secretion. Our results suggest that local ovarian factors, rather than hCG, predominate in regulating VEGF mRNA and protein production by human midluteal phase luteal cells. For VEGF, a lack of a direct luteal steroidogenic effect was also demonstrated.

We investigated the effect of nicotine and its methylated metabolite, N-methyl-nicotine (M-nicotine), on human luteal cells by measuring release of p

IGFs seem to contribute to the endothelial dysfunction observed in some vascular diseases. Because locally increased IGFs levels were detected in the preeclamptic fetoplacental unit, we hypothesized their involvement in the dysregulation of fibrinolysis and vascular tone typically observed in the fetoplacental compartment in this pregnancy disease. Therefore, in human umbilical vein endothelial cells (HUVECs), the potential effect of IGFs on the synthesis of plasminogen activators (PAs), PA inibitor-1 (PAI-1), and vasodilator and vasoconstrictor prostaglandins (PGs) was investigated. Moreover, in HUVECs treated with IGFs, the expression of cyclooxygenase (COX)-2, the rate-limiting enzyme in PG synthesis, was evaluated. HUVECs were treated for 24 h with IGFs (1–100 ng/ml) or IL-1β (0.1 ng/ml). PA, PAI-1, and COX-2 mRNA was determined by RT-PCR and PG release and PA activity by RIA and colorimetric assay, respectively. We demonstrated an inhibition of urokinase-type PA activity and a 50% reduction of urokinase-type PA mRNA in HUVECs treated with IGFs. No effect was seen on PAI-1. Finally, both IGFs significantly decreased all PGs tested and COX-2 mRNA, whereas, as expected, IL-1β had an opposite effect. In conclusion, our results suggest for IGFs a potential involvement in the endothelial dysfunction observed in preeclamptic fetoplacental unit.

Abstract: It is well known that an adequate endometrial receptivity is required for successful implantation in both natural and assisted reproductive cycles. In particular, a brief “implantation window”, during which endometrium undergoes anatomical and molecular changes necessary for embryo implantation, has been observed. The hormonal treatment applied to induce ovulation seems to be able to modify the normal development of the prenidatory endometrium, with possible negative effect on the implantation rate. For this reason, several attempts have been made to identify specific markers of endometrial receptivity, useful for predicting implantation outcome in clinical practice. Even if different histological, immunohistochemical, and ultrasonographic parameters are studied, none unfortunately has been univocally shown to be predictive of pregnancy outcome. Therefore, the evaluation of endometrial receptivity remains a challenge in clinical practice.