[Show abstract][Hide abstract] ABSTRACT: Catechol-O-methyltransferase (COMT) activity has been reported to be higher in African Americans (AA) than Caucasians (Cau). COMT converts 2- and 4-hydroxy (OH) estrogens to 2- and 4-methoxyestrogens, respectively, and can increase estrogenic milieu locally in tissues. To assess whether the increased incidence of preterm birth (PTB) among AA women is associated with single-nucleotide polymorphism (SNP) in the COMT gene, we examined variations in maternal and fetal COMT genes and their association with pregnancy outcomes (term vs preterm pregnancies) using 4 functional SNPs: rs4633, rs4680, rs4818, and rs6269 in both AA and Cau. We analyzed samples from 267 AA women (191 term and 76 preterm pregnancies) and 339 Cau (194 term and 145 preterm pregnancies) in this study. The results showed a significant difference (P < .05) in allele and genotype frequencies between term and preterm AA and Cau women in 3 SNPs in both maternal and fetal DNA. The analysis revealed that in AA fetal COMT genes, SNP rs4818 is associated with PTB at the allele (C; P < .001), genotype (C/C; P < .01), and 2- (P < .03) and 3 (P < .04)-window haplotype levels. Multidimensionality reduction analysis also showed a significant (P < .01) association between rs4818 and PTB. In conclusion, our study demonstrated that a synonymous polymorphism, rs4818 in the fetal COMT gene, is associated with PTB in AA.
[Show abstract][Hide abstract] ABSTRACT: The purpose of this study was to evaluate the expression and function of catechol-O-methyltransferase in human fetal membranes at term.
Fetal membranes obtained from women between 38-42 weeks of gestation, after (1) vaginal delivery with spontaneous labor and (2) prelabor elective cesarean section (no labor), were assayed for catechol-O-methyltransferase expression using quantitative real-time polymerase chain reaction analysis, immunohistochemistry, and Western blot analysis. Prostaglandin E(2) secretion from amnion and choriodecidua explants treated with or without catechol-O-methyltransferase inhibitor was assayed by enzyme-linked immunosorbent analysis.
Amnion layer of fetal membranes from laboring women expressed significantly higher levels of catechol-O-methyltransferase, compared with those from women with no labor. Catechol-O-methyltransferase was higher in the amnion layer than in choriodecidua. Selective catechol-O-methyltransferase inhibition significantly decreased prostaglandin E(2) production from fetal membranes.
Labor increases catechol-O-methyltransferase expression in the amnion of human fetal membranes. Selective catechol-O-methyltransferase inhibition decreased prostaglandin E(2) secretion in fetal explant cultures, suggesting a role for catechol-O-methyltransferase in human labor and delivery.
American journal of obstetrics and gynecology 09/2009; 201(5):496.e1-7. · 3.97 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Recent studies have suggested that germline stem cells may generate new follicles in the adult murine ovary. In this study, the authors use a pou5f1-enhanced green fluorescent protein (EGFP) transgenic mouse model to study the expression of stem and germ cell markers in adult murine ovaries. Immunohistochemical analyses and reverse transcription polymerase chain reaction were performed to detect the expression of mouse vasa homologue, stem cells factor receptor, stage-specific embryonic antigen 1, synaptonemal complex proteins, disrupted meiotic, and growth differentiation factor-9 in GFP+ ovarian tissues. GFP+ cell aggregates of nonfollicle structures were identified and isolated from adult B6.CBA-Tg(pou5f1-EGFP)2Mnn/J transgenic mouse ovaries. This study shows the presence of cell aggregates that are distinct from ovarian follicles and are coexpressing germline and stem cell surface markers in adult murine ovaries. These cell aggregates may represent a mixed population of germ cells and germline stem cells. Further research is necessary to evaluate the plasticity of the potential stem cell population in these cell aggregates.
[Show abstract][Hide abstract] ABSTRACT: Catechol-O-methyltransferase (COMT) enzyme catalyzes the methylation of the 2- or 4-hydroxyestrogens to 2- or 4-methoxyestrogens. Both the hydroxyestrogens and methoxyestrogens have been shown to block or enhance the effects of estrogen respectively. Our objective was to investigate the potential role of COMT in parturition and cervical ripening using a rat model. Immunohistochemistry was conducted to detect and localize the COMT protein in rat uterine tissues during pregnancy. We measured the longitudinal changes in urinary 2-hydroxyestrogen before, during, and after pregnancy in rats. Animal studies were conducted to determine the effect of treatment with a selective COMT inhibitor on (1) mifepristone-induced preterm birth and (2) cervical resistance to stretch in pregnant rats. The intensity of staining for the COMT protein differed within the luminal epithelium, uterine gland epithelium, endometrium, and myometrium during pregnancy. Levels of staining for the COMT protein in rat myometrium were highest on day 1 and lowest on days 8 and 13, but high levels returned by days 16 and 19 of pregnancy. The levels of urinary 2-hydroxyestrogen gradually increased in the first 2 weeks of pregnancy, peaked from days 16 to 18 of pregnancy, and then gradually returned to pre-pregnancy levels after delivery. The percentage of pups retained in the uterus of pregnant rats treated with both mifepristone and COMT inhibitor (48 +/- 15%) was significantly higher (P < 0.05) when compared with the value of pregnant rats treated with mifepristone alone (12 +/- 4%). The resistance to stretch was significantly higher (P < 0.05) in cervical tissues from the pregnant rats treated with COMT inhibitor (0.28) when compared with cervical tissues taken from rats treated with vehicle control (0.18). Modulation of COMT activity may play a role in the regulation of myometrial contractility and cervical ripening during pregnancy.
[Show abstract][Hide abstract] ABSTRACT: To study if spontaneous contractions augmented by proteinase-activated receptor-2 (PAR-2)-activating peptide serine-leucine-isoleucine-glycine-arginine-leucine (SLIGRL) involve coactivation of membrane chemoceptors and are associated with expression of PAR-2 mRNA in non-pregnant and pregnant rat myometrium.
Non-pregnant, mid-pregnant, and late pregnant rat uterine horn and small intestine segments were snap-frozen in liquid nitrogen to determine PAR-2 mRNA levels by real time polymerase chain reaction (PCR). Uterine rings were used for isometric tension recording. Effect of SLIGRL (0.1 mM) on spontaneous contractions before and after exposure to ibuprofen (cyclooxygenase inhibitor, 1.0 microM), SQ-29548 (thromboxane A(2) receptor inhibitor, 1.0 microM), ketotifen (histamine 1 receptor inhibitor, 10 microM), WEB-2170BS (platelet-activating factor (PAF) receptor inhibitor, 10 microM), atropine (muscarinic receptor inhibitor, 0.1 microM), or ketanserin (serotonin receptor inhibitor, 10 microM) were compared. Paired t-test and one-way ANOVA followed by Dunnett's or Newman-Keuls post hoc tests were used for statistical analysis when appropriate.
The agents did not significantly affect time-associated decay in spontaneous contractile activity in any group of the tissues. Activation of spontaneous contractions induced by SLIGRL in non-pregnant rat myometrium did not involve coactivation of membrane chemoceptors, while in mid-pregnant rat myometrium coactivation of prostanoid, histamine, and serotonin receptors and in late pregnant rat myometrium coactivation of thromboxane receptors was noted. Expression of PAR-2 mRNA was similar in non-pregnant, mid-pregnant, and late pregnant rat myometrium.
Expression of PAR-2 in rat myometrium is not dependent on gestational age. Stimulation of PAR-2 is associated with production/release of cyclooxygenase pathway product(s) activating thromboxane/prostaglandin H2 receptors, partial involvement of histamine H1 receptors and serotonin receptors in midpregnancy and thromboxane A2/prostaglandin H2 receptors in late pregnancy.
European Journal of Obstetrics & Gynecology and Reproductive Biology 01/2007; 130(1):51-9. · 1.63 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The catechol-O-methyltransferase enzyme catalyzes the methylation of the catechol estrogens, 2- or 4-hydroxyestrogen, to 2- or 4-methoxyestrogen. Both the hydroxy estrogens and methoxy estrogens were shown to modulate the effects of estrogen. Because catechol-O-methyltransferase activity controls levels of these metabolites, it may help regulate the cellular estrogenic milieu. In this study, we examined the regulation of catechol-O-methyltransferase expression in human myometrial cells.
Catechol-O-methyltransferase expression was assessed by reverse transcription-polymerase chain reaction, Western blot, and luciferase assays in human myometrial cells after treatment with estrogen or progesterone. Catechol-O-methyltransferase expression was measured in cells after treatment with tumor necrosis factor alpha (TNFalpha) alone or with lactacystin, a proteasome inhibitor. Luciferase assays were also conducted using human myometrial cells containing an estrogen response element-luciferase reporter gene to measure levels of estrogen-mediated transactivation after treatment with estrogen and increasing concentrations of 2-hydroxestrogen.
Catechol-O-methyltransferase expression was down-regulated by progesterone or estrogen. Tumor necrosis factor alpha upregulated catechol-O-methyltransferase expression, whereas cotreatment with lactacystin attenuated this response, suggesting that TNFalpha activated nuclear factor kappa B to induce catechol-O-methyltransferase expression. Increased concentrations of 2-hydroxyestrogen attenuated estrogen-mediated transcription in the myometrial cells.
Catechol-O-methyltransferase expression may be regulated in the myometrium to control the local action of estrogen. Low levels of catechol-O-methyltransferase in the myometrium would result in an accumulation of 2-hydroxyestrogen and may antagonize the local effect of estrogen. High levels of catechol-O-methyltransferase in the myometrium would result in lower levels of 2-hydroxyestrogen and may increase sensitivity to estrogen.
Obstetrics and Gynecology 01/2007; 108(6):1439-47. · 4.37 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This study examines the relationship between inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in the control of cervical ripening and parturition under normal (normal term pregnancy) and abnormal (preterm labor and prolongation of pregnancy) conditions by (a) measuring changes in the collagen both visually and quantitatively, (b) localizing and characterizing iNOS and COX-2 under normal conditions, and (c) characterizing the changes in iNOS and COX-2 under abnormal conditions. Cervices are obtained from estrus and timed pregnant Sprague-Dawley rats (n=4-10 per group). Preterm labor is induced with Onapristone (3 mg/rat; progesterone antagonist) and the prolongation of pregnancy with progesterone (2.5 mg, twice daily). Collagen changes are measured and visualized with the picrosirius polarization method. RT-PCR is used to characterize the mRNA expression (p<0.05), and immunohistochemistry is used to localize the protein expression for iNOS and COX-2. The organization and birefringence of the collagen during pregnancy decreased and is supported by changes in the luminosity (p<0.001). The iNOS and COX-2 enzymes were localized in cervical smooth muscle, vascular smooth muscle, and epithelium. Under normal conditions, iNOS mRNA levels decreased as COX-2 mRNA levels increased demonstrating an inverse correlation (Spearman r = -0.497; p=0.00295). Onapristone stimulated preterm labor, increasing the iNOS and COX-2 mRNA (p<0.05). The increase demonstrated a positive correlation (Spearman r = 0.456; p=0.03). Progesterone prolonged pregnancy, decreasing the iNOS and COX-2 mRNA (p=0.036). In conclusion, there may be an interaction between the nitric oxide and prostaglandin pathways in cervical ripening and parturition.
Journal of Histochemistry and Cytochemistry 06/2006; 54(6):623-39. · 2.40 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We tested the hypothesis that oxytocin (OT) contracts blood vessels via vasopressin V1A (VP) receptors, and that this depends on pregnancy.
Concentration-contraction relationships (CCR) to OT and VP (10(-12)-10(-6) mol/L) were obtained in different blood vessels. CCR were obtained in uterine arteries (UA) from nonpregnant, mid-pregnant, and late pregnant rats (n = 6-10 per group) in the absence and presence of selective antagonists (10(-7) mol/L).
Sensitivity to OT, but not to VP, is attenuated in pregnant rat UA. Antagonists shifted CCR of OT and VP to the right, and, to a lesser extent, of the counterpart, in all UA. VP antagonist depresses oxytocin CCR much more than OT antagonist in pregnant rat UA.
OT and VP contract UA via their own receptors, although partial cross-activation is evident. Adaptation to pregnancy led to attenuated sensitivity of UA smooth muscle to OT and transformed OT receptors into VP-like ones.
American journal of obstetrics and gynecology 02/2006; 194(1):252-60. · 3.97 Impact Factor