Eric P. Spaziani

The expression of cyclooxygenase-2 (COX-2) in amnion and decidua following spontaneous labor.

OBJECTIVE Prostaglandins production rises dramatically during term and preterm labor. The source of this production is thought to be the fetal membranes and maternal decidua. The enzyme responsible for the conversion of arachidonic acid to the prostaglandins and related endoperoxides is variously known as prostaglandin synthase or cyclooxygenase (COX). An inducible form of this enzyme, COX-2, has been described in several tissues. The purpose of this study was to investigate a possible role for COX-2 in labor by comparing the COX-2 content in amnion and decidua from laboring and non-laboring patients. STUDY DESIGN Fetal membranes from seven normal labor and ten elective cesarean sections at term were collected immediately following delivery. The maternal age and gravity were similar between the groups. The amnion and decidua were identified, washed in sterile saline, frozen in liquid nitrogen and stored in -70 degrees C. COX-2 expression was determined using Western Blot analysis with a purified COX-2 antibody. A scanning densitometer was used to quantify the bands. Results were expressed as mean +/-S.D. ng/50 micrograms protein. RESULTS The concentration of COX-2 in amnion of laboring women showed a twofold increase (240.0 +/- 17.6 vs. 120.7 +/- 5.1) compared to the non-labored group (p < 0.05). The concentration in the decidua showed no significant increase during labor (38.1 +/- 7.5 vs. 26.4 +/- 2.1, p > 0.05). CONCLUSION We evaluated the role of COX-2 in normal labor. Our study demonstrates that COX-2 is significantly induced in the amnion following spontaneous labor. These findings suggest that the induction of amnion COX-2 may be involved in the process of human labor.

The induction of cyclooxygenase-2 (COX-2) in intact human amnion tissue by interleukin-4

Infection is a major cause of preterm labor. Amniotic fluid from women in preterm labor associated with intrauterine infection contains increased concentrations of cytokines. The mechanism underlying this association may be a cytokine-mediated stimulation of amnion cell prostaglandin production. The biosynthesis of prostaglandins from arachidonic acid is regulated by the enzyme cyclooxygenase which exists in two forms; the constitutive form (COX-1) and the other mitogen inducible (COX-2). The purpose of this study was to evaluate the effect of the cytokine interleukin-4 (IL-4) on cyclooxygenase activity and PGE2 production in amnion. Amnion tissue was taken at caesarean section from term women not in labor and immediately incubated for 2 hours in media containing concentrations of IL-4 ranging from 1 to 100 ng/ml. An increase in both COX-2 enzyme and prostaglandin E2 (PGE2) production was observed for all concentrations of IL-4 greater than 25 ng/ml (P < 0.05, n = 8). No change in COX-1 was observed. Our data suggest that the cytokine IL-4 may be involved in the pathogenesis of premature labor by inducing COX-2 in amnion tissue resulting in increased production of PGE2 and subsequent myometrial activity.

Changes in prostaglandin E2 and F2α during vitellogenesis in the florida crayfish Procambarus paeninsulanus

While the role of eicosanoids in reproduction in vertebrate species has been well established, the role of these fatty acid derivatives in invertebrate species has not been as well characterized. The purpose of this study was to investigate changes in prostaglandins E2 and F2α during vitellogenesis in the crayfish Procambarus paeninsulanus. In homogenates of crayfish ovaries taken at various stages of development, the rate of prostaglandin synthesis and the concentrations of prostaglandins E2 and F2α increased during the final stages of yolk production just prior to ovulation. A gradual increase in prostaglandin E2 amounts was observed throughout the progression of vitellogenesis. The data suggests the possible involvement of prostaglandins in regulatory events associated with vitellogenesis and the induction of ovulation in Procambarus paeninsulanus.

The Effect of Interleukin‐1β and Interleukin‐4 on the Expression of Prostaglandin Receptors EP1 and EP3 in Amnion WISH Cells

PROBLEM: Although prostaglandin E2 (PGE2) is believed to modulate biochemical and immunological events leading to parturition, the role of prostaglandin E receptors during labor has not been investigated.

The effect of prostaglandin E2 and prostaglandin F2α on ovarian tissue in the Florida crayfish P rocambarus paeninsulanus

Prostaglandins are oxygenated fatty acid derivatives of arachidonic acid involved in a number of vertebrate and invertebrate reproductive processes. While the role of prostaglandins in vertebrate reproduction has been well established, their function in the invertebrate has not been investigated extensively. The purpose of this study was to investigate the effect prostaglandin E2 (PGE2) and prostaglandin F2 alpha (PGF2 alpha) on ovarian tissue in the crayfish Procambarus paeninsulanus. PGF2 alpha induced contraction of ovarian tissue in a dose-dependent manner, while PGE2 alpha had little effect. Incubation of ovarian tissue with PGF2 alpha also produced a dose-dependent increase in cAMP. In addition, the experimental technique of back-phosphorylation, in which exogenously added cAMP-dependent protein kinase is able to transfer phosphate to previously non-phosphorylated proteins, revealed that PGF2 alpha-induced increases in cAMP resulted in the specific phosphorylation of a 45 kDa protein. These data give evidence that PGF2 alpha may be involved in crustacean ovulation by causing the cAMP-mediated contraction of ovarian tissue and that this contraction may involve the phosphorylation of proteins associated with the cytoskeleton.

Variation in selected unsaturated fatty acids during vitellogenesis in the Florida freshwater crayfish Procambarus paeninsulanus

Summary Fatty acids and their derivatives are involved in events associated with reproduction in invertebrates. The purpose of this study was to investigate the presence and variation in amount of selected fatty acids during vitellogenesis in the crayfish Procambarus paeninsulanus. Particular attention was given to possible precursors of eicosanoid production. Ovarian homogenates were prepared and analyzed by gas chromatography. Results demonstrated a dramatic increase in several fatty acids fiom the onset of secondary vitellogenesis to just prior to ovulation. It is possible that unsaturated fatty acids or their derivatives may be involved in the importation of exogenous proteins to support yolk formation. In addition, results demonstrate ample substrate exists in crustacean ovaries to support production of reported eicosanoids by lipoxygenase andfor cyclooxygenase pathways.

Dose-dependent effects of prostaglandin D2 on hemodynamics, renal function, and blood gas analyses☆

Dose-response effects of prostaglandin D2 (0.125, 0.25, 0.5, and 0.75 micrograms/kg/min) infused intravenously in pentobarbital-anesthetized dogs were studied with particular reference to renal, pulmonary, and systemic effects. Another group receiving the vehicle alone served as controls. Prostaglandin D2 administration resulted in a significant dose-dependent increase in renal artery flow, urine output, creatinine clearance, plasma renin activity, sodium excretion, potassium excretion, and pulmonary artery pressure. A significant decrease occurred in renal resistance and arterial PO2. There were no appreciable changes in mean arterial pressure, heart rate, hematocrit, platelet count, arterial pH, and PCO2. In the vehicle control group, all other parameters remained relatively stable, except for some increase in the mean arterial pressure, plasma renin activity, and potassium excretion. The results of this study suggest that prostaglandin D2 administered intravenously at levels lower than those required to produce adverse pulmonary and systemic effects will improve the renal blood flow and function.

Corticotropin-Releasing Hormone Increases the Expression of the Prostaglandin E2 Receptor Subtype EP1 in Amnion WISH Cells

Abstract The purpose of this study was to investigate the effect of corticotropin-releasing hormone (CRH) on the expression of the prostaglandin (PG) E2 EP1 receptor subtype and PGE2 production in amnion WISH cells (AWC). AWC cultures were incubated with CRH. Culture fluid was collected for PGE2 measurement, and the cells were collected and analyzed for EP1 protein and mRNA. Immunohistochemical localization of the EP1 receptor was also performed. Incubation of AWC with CRH resulted in a dose-dependent increase (r = 0.97) in the level of EP1 receptor protein (P < 0.001). Coincubation of AWC with CRH and indomethacin resulted in the decreased production of PGE2 while having no effect on EP1 receptor expression. A significant but not dose-dependent increase in EP1 mRNA expression was also observed (P < 0.01). Immunohistochemical evaluation verified cell membrane localization of the receptor in both stimulated and unstimulated cells and confirmed the increased expression of EP1 receptor in response to CRH. Incubation of AWC with CRH also resulted in increased culture fluid PGE2 levels (P < 0.01). These results suggest that the role CRH plays in the initiation of labor may also involve the promotion of elevated PGE2 levels and increased expression of the EP1 receptor in amnion.

Modulation of the prostaglandin E receptor : A possible mechanism for infection-induced preterm labor

OBJECTIVE To evaluate the modulatory effects of interleukin (IL)-1beta and prostaglandin (PG)E2 on the PGE2 receptor subtype EP1 in amnion cell cultures. METHODS Amnion cell cultures were incubated in increasing concentrations of (IL)-1beta or PGE2. Cultures were also incubated in high concentrations of IL-1beta and PGE2 in combination. Changes in EP1 receptor levels were evaluated by western and northern blot analysis. Culture fluid PGE2 levels were measured by enzyme-linked immunosorbent assay. RESULTS EP1 receptor protein levels decreased with increasing levels of PGE2 (r = -0.82, P < .05). EP1 receptor protein (r = 0.95, P < .05), EP1 mRNA (r = 0.95, P < .01), and culture fluid PGE2 levels (P < .01) were all increased after IL-1beta administration. EP1 receptor levels also increased approximately fourfold in response to IL-1beta incubation even in the presence of high agonist (PGE2) concentrations (P < .01). CONCLUSION The results of this study show that IL-1beta might be involved in infection-induced preterm labor by interfering with the normal regulation of EP1 receptor levels and with the promotion of increased PGE2 production in amnion tissue.

The effect of prostaglandin D2 (PGD2) on circulating eosinophils

Infusion of prostaglandin D2 (PGD2) into dogs for 60 minutes at a rate of 1 microgram/kg/min produced a marked and rapid reduction in circulating eosinophils within 2 minutes, without any significant change in neutrophil count. Recovery was also rapid, with levels similar to those of a control group of dogs being reached 60 minutes after finishing the infusion. In dogs given PGD2 the hematocrit rose more rapidly than in the control group. The platelet count did not alter significantly.