Attenuated tubal and endometrial urocortin 1 and corticotropin-releasing hormone receptor expression in ectopic pregnancy

Fallopian tube (FT) and endometrial urocortin 1 (Ucn1) and corticotropin-releasing hormone (CRH)-receptor (CRH-R1/CRH-R2) expression were examined using quantitative real-time polymerase chain reaction (RT-PCR) and immunohistochemistry in nonpregnant and pregnant women (intrauterine, IUP; ectopic pregnancy, EP). Tubal Ucn1 messenger RNA (mRNA) expression was higher in luteal compared to follicular phase (P < .01) and equivalent to follicular phase in FT from EP. Tubal CRH-R1/CRH-R2 mRNA was lower in luteal phase (P < .05) and in FT from EP compared to follicular phase (P < .01). Ucn1 mRNA was lower in endometrium from EP compared to IUP (P < .05). Corticotropin-releasing hormone-R1 mRNA was higher in endometrium from EP compared to viable IUP (P < .05). No differences were observed in CRH-R2 expression. Corticotropin-releasing hormone-R1 protein was primarily localized to epithelium of FT and endometrium. Quantitative analysis of tubal CRH-R1 protein expression reflected that seen at the mRNA level but endometrial expression was equivocal. The demonstration of attenuated tubal/endometrial Ucn1/CRH-R expression in EP further supports a role of the CRH-family in embryo implantation.

Hypoxia and preeclampsia: increased expression of urocortin 2 and urocortin 3

OBJECTIVE

Urocortin 2 (Ucn2) and urocortin 3 (Ucn3) are new members of the corticotrophin-releasing hormone (CRH) family of peptides expressed and localized in human placenta. In the current study, we aimed to asses whether hypoxia affects placental Ucn2/Ucn3 messenger RNA (mRNA) expression and protein localization in physiological or pathological hypoxia and to evaluate whether the effect is modulated by the hypoxia-inducible factor 1alpha (HIF-1alpha).

METHODS

Early first-trimester placental specimens from elective termination of pregnancy were used for villous explants and term placental tissue were used for primary cell cultures. The samples were incubated under different oxygen conditions; parallel sets exposed to hypoxia re-oxygenation (HR). Dimethyloxalylglycine (DMOG), an HIF-1alpha stabilizer, was used to mimic the effects of hypoxia in villous explants. Real-time polymerase chain reaction (PCR) and immunohystochemistry were performed on early pregnancy and preeclamptic (PE) placentae. mRNA levels were measured on villous explants and cell cultures incubated under different oxygen and reagent conditions.

RESULTS

Both Ucn2 and Ucn3 mRNA expression was significantly higher at 6 to 9 weeks of gestation than 10 to 12 wks and in primary trophoblast cell cultures and explants exposed to low O(2) tension (3%) compared to 20% O(2). Strong Ucn2/Ucn3 immunoreactivity was present in trophoblast villi from 6 weeks placentae. Ucn2 immunostaining was stronger in early PE (E-PE) samples relative to controls whereas Ucn3 showed stronger immunoreactivity in late-PE (L-PE) placentae. Only Ucn2 transcript levels increased in HR explants. Ucn2 and Ucn3 expression by first-trimester explants was significantly greater in the presence of DMOG. All PE placentae expressed significantly higher Ucn2 and Ucn3 mRNA compared to controls.

DISCUSSION

Placental Ucn2 and Ucn3 expression is sensitive to O(2) tensions and mediated by HIF-1alpha. During early pregnancy, Ucn2/Ucn3 may influence trophoblast proliferation and establishment of pregnancy. In PE placentae, the increased expression of both peptides may reflect a response to the oxidative stress.

Secretory endometrium highly expresses urocortin messenger RNA and peptide: possible role in the decidualization process

BACKGROUND

Urocortin (UCN) gene expression and synthesis have been reported in epithelial and stromal cells of the human endometrium. In this study we evaluated (i) UCN messenger RNA (mRNA) expression and peptide production in uterine specimens collected throughout the endometrial cycle, (ii) UCN secretion after decidualization of cultured human endometrial stromal cells (HESCs) and (iii) the effect of UCN on endometrial decidualization.

METHODS

HESCs were isolated from samples of human endometrium collected from healthy patients with normal menstrual cycle and cultured in presence of cAMP, 17-beta-estradiol (E(2)) + medroxyprogesterone acetate (MPA) and UCN. UCN levels were measured in endometrial extracts by an enzyme immunoassay, and changes of endometrial UCN mRNA expression were measured by RT-PCR analysis.

RESULTS

UCN peptide concentrations and mRNA expression were highest in the secretory phase of the menstrual cycle (P < 0.001, late secretory versus early and late proliferative phase) and higher in the late than the early secretory phase (P < 0.01). After decidualization of HESC with cAMP or E(2) + MPA, UCN levels rose in parallel with prolactin concentrations by days 6 (P < 0.01, for all). Finally, the addition of UCN to HESCs, with or without E(2) + MPA, induced the release of prolactin.

CONCLUSIONS

The evidence that (i) UCN is highly expressed in the secretory phase of the endometrial cycle; (ii) cAMP and E(2) + MPA modulate secretion of UCN and (iii) UCN induces HESCs decidualization together suggest a possible role for UCN in endometrial physiology.

Reduced maternal plasma urocortin concentrations and impaired uterine artery blood flow at human mid pregnancy

OBJECTIVE

Urocortin is a placental neuropeptide belonging to the family of corticotropin-releasing factors (CRFs), playing a role in the uteroplacental blood flow regulation through the binding to specific CRF receptors. Since CRF receptors are expressed in the uterine vascular bed of pregnant rats, and because urocortin has a relaxant effect on uterine vasculature, we evaluated mid-gestation plasma urocortin levels in women with impaired blood flow through uterine arteries.

METHODS

Maternal plasma urocortin was assayed by specific radioimmunoassay and uterine artery resistance index (RI) by Doppler evaluation at 22-24 weeks' gestation in 57 healthy pregnant women, of which 29 showed a monolateral or bilateral uterine artery notch. Statistical analysis was performed by one-way analysis of variance (ANOVA), followed by post-hoc Tukey test for multiple comparison and Pearson correlation coefficient test.

RESULTS

The mean uterine artery RI was significantly (P <.001) higher in women with a notch than healthy controls. Mean +/- SEM maternal plasma urocortin levels were significantly (P <.001) lower in women with unilateral (52.03 +/- 3.25 pg/mL) or bilateral (47.01 +/- 4.16 pg/mL) uterine artery notch than in healthy control pregnant women (84.01 +/- 3.5 pg/mL). While no difference was found in urocortin levels between patients with unilateral or bilateral uterine artery notch, urocortin concentrations inversely correlated with the mean RI (Pearson r = -0.7318; 95% confidence interval -0.8334 to -0.5822; P <.0001).

CONCLUSIONS

The present findings suggest that reduced levels of circulating urocortin are associated with increased uterine artery resistances and support the hypothesis that urocortin may regulate uterine artery tone at mid gestation.

Endogenous urocortins reduce vascular tone and renin-aldosterone/endothelin activity in experimental heart failure

AIMS

To investigate the role of the endogenous urocortin peptides in heart failure (HF) through blockade of the corticotropin-releasing factor receptor 2 (CRF-R2).

METHODS AND RESULTS

Eight sheep were administered the CRF-R2 antagonist CRF(9-41) (1.5 mg bolus) before (Normal) and after development of pacing-induced HF. Compared with controls, CRF(9-41) in HF significantly increased mean arterial pressure (MAP) (71+/-2 vs. 75+/-2 mmHg, P=0.0024) and calculated total peripheral resistance (CTPR) (33.3+/-5.2 vs. 39.4+/-5.9 mmHg/L/min, P=0.0455). Similar trends were observed in the Normal state (MAP 87+/-1 vs. 89+/-2 mmHg, P=0.0689; CTPR 21.9+/-2.0 vs. 24.4+/-2.4 mmHg/L/min, P=0.0731). Left atrial pressure was elevated similarly in both states (Normal P=0.0013; HF P=0.0298), whereas cardiac output tended to be reduced (Normal P=0.0614). CRF(9-41) increased plasma urocortin-I (Normal 10.3+/-0.8 vs. 19.8+/-1.3 pmol/L, P<0.001; HF 14.4+/-0.9 vs. 25.3+/-0.8 pmol/L, P<0.001), renin (Normal 0.34+/-0.06 vs. 0.41+/-0.02 nmol/L/hr, P=0.013; HF 1.14+/-0.29 vs. 1.57+/-0.36 nmol/L/hr, P=0.0326), aldosterone (Normal 370+/-62 vs. 563+/-99 pmol/L, P=0.0813; HF 662+/-141 vs. 1024+/-209 pmol/L, P=0.095), and endothelin-1 (HF 3.18+/-0.18 vs. 4.74+/-1.04 pmol/L, P=0.0087). MAP, CTPR, renin, and endothelin-1 responses to CRF-R2 antagonism were significantly greater in HF than in the Normal state (P=0.049, 0.0427, 0.0311, and 0.0412, respectively).

CONCLUSION

These data suggest that the endogenous urocortin peptides contribute to the suppression of vascular tone and renin-angiotensin-aldosterone/endothelin activation in HF and thus, play a protective compensatory role in this disorder.

Detection of corticotropin-releasing hormone receptors R1 and R2 (CRH-R1, CRH-R2) using fluorescence immunohistochemistry in the myometrium of women delivering preterm or at term

OBJECTIVE

To determine differences in expression of corticotropin-releasing hormone receptors R1 and R2 in the myometrium of women delivering preterm or at term, with or without labor.

MATERIAL AND METHODS

Small pieces of myometrial smooth muscle were taken from forty patients undergoing caesarian section. One sample each was taken from all preterm and term patients, with and without labor. Antibodies against CRH-R1/2 and CRH-R2 were used for localization by conventional fluorescence immunohistochemistry. The evaluation of staining was based on examination of the entire histologic section by three independent observers.

RESULTS

In women at term, CRH-R2 levels were elevated before labor and decreased with the onset of labor. In eight of 10 term samples from women in labor, no staining was detected. In preterm patients we found no difference in CRH-R2 staining between women with and without labor. The intensity of staining for CRH-R1/2 was generally uniform in all four groups.

CONCLUSION

The high level of CRH-R2 expression in term patients without labor, together with the subsequent decrease of CRH-R2 in the myometrium during progression of labor, is consistent with the possibility that CRH may have autocrine/paracrine effects on myometrial contractility in the lower segment of the uterus.