Synthesis of prostaglandins by pig blastocysts cultured in medium containing estradiol or catechol estrogen.

Two experiments were conducted to determine the effects of 2-hydroxy-estradiol-17 beta (2-OH-E2; 0, 50 and 100 microM) and estradiol-17 beta (E2; 0, 25 and 50 microM) on prostaglandin (PG) E and PGF2 alpha synthesis by day-10 pig blastocysts (day 0 is first day of estrus). Blastocysts were incubated in a modified Krebs-Ringer bicarbonate medium, supplemented with bovine serum albumin (4 mg/ml) and the vitamins and amino acids (essential and nonessential) in Minimum Essential Medium (without phenol red or antibiotics). The incubations were conducted at 39 degrees C for three 2-h periods; the second and third periods included an E2 or catechol estrogen treatment. Release of PGF2 alpha into the culture medium decreased (p less than 0.001) linearly with increasing concentrations of 2-OH-E2 in both periods. Release of PGE was not affected by 2-OH-E2, therefore 2-OH-E2 increased (p less than 0.06) the PGE:PGF2 alpha. When E2 was added to the medium, release of PGE was decreased (p less than 0.01) during the second and third periods. Release of PGF2 alpha also was decreased (p less than 0.05) by E2 during period 2, but E2 did not alter the PGE:PGF2 alpha. Content of PGs in blastocysts at recovery was less than 10% of the PGs released in vitro. Therefore, these studies demonstrate effects of both the primary and catechol forms of E2 on the synthesis of PGE and PGF2 alpha. Catechol estrogens and E2 may inhibit PG synthesis and modify the PGE:PGF2 alpha during the establishment of pregnancy in pigs.     

Conceptus-derived prostaglandins regulate endometrial function in sheep

In sheep, the trophectoderm of the elongating conceptus secretes interferon tau (IFNT) and prostaglandins (PGE2, PGF2alpha, PGI2). The PGs are derived from PG synthase 2 (PTGS2), and inhibition of PTGS2 in utero prevents conceptus elongation. IFNT increases expression of many genes in the endometrial epithelia that regulate conceptus elongation. This study tested the hypothesis that PGs secreted by the conceptus regulate endometrial functions that govern conceptus elongation. Cyclic ewes received intrauterine infusions of control vehicle or early pregnancy levels of IFNT, PGE2, PGF2alpha, or PGI2 from Days 10-14 postestrus. Expression levels of endometrial GRP, IGFBP1, and LGALS15, whose products stimulate trophectoderm cell migration and attachment, were increased by PGE2, PGI2, and IFNT. All PGs and IFNT increased expression of the HEXB protease gene, but only IFNT increased the CST6 protease inhibitor gene. Differential effects of PGs were observed for expression of the CTSL protease gene and its inhibitor, CST3. IFNT, PGF2alpha, and PGI2 increased ANGPTL3 expression, but only IFNT and PGE2 increased HIF1A expression, both of which regulate angiogenesis. For glucose transporters, IFNT and all PGs increased SLC2A1 expression, but only PGs increased SLC2A5 expression, whereas endometrial SLC2A12 and SLC5A1 expression levels were increased by IFNT, PGE2, and PGF2alpha. Infusions of all PGs and IFNT increased the amino acid transporter SLC1A5, but only IFNT increased SLC7A2 expression. In the uterine lumen, only IFNT increased glucose levels, and only PGE2 and PGF2alpha increased total amino acids. These results indicate that PGs and IFNT from the conceptus coordinately regulate endometrial functions important for growth and development of the conceptus during the peri-implantation period of pregnancy.     

Prostaglandin translocation from the lumen of the rabbit uterus in vitro in relation to day of pregnancy or pseudopregnancy

Transport of 3H-labeled prostaglandins (PGs) E2 and F2 alpha from the uterine lumen across the uterine wall has been studied in rabbit uteri in vitro in incubations lasting up to 180 min, in relation to sexual state of the rabbit, incubation temperature, intraluminal PG concentration, addition of metabolic inhibitors and time of incubation. PG accumulation by the tissue increased rapidly up to 30 min and then remained relatively constant. By 30 min, radioactivity was found in the external incubation medium, and this increased linearly with time. The translocation of PGF2 alpha was significantly greater in pseudopregnant than in pregnant animals on Day 6, whereas that of PGE2 was significantly higher in pregnant than in pseudopregnant animals on Day 6.8. In pregnant animals, both PGF2 alpha and PGE2 were translocated to the exterior more rapidly on Day 6.8 than on Days 5 or 6. Transport of PGs was reduced by low temperature, unaffected by metabolic inhibitors and only that of PGE2 increased with increased (5 microM) intraluminal concentrations. During incubation, the tissue remained viable as judged by T/M ratios (dpm tissue/dpm medium) for 204 thallium. Transport of [14C] sucrose was much slower than that of [14C] urea, which was greater than the fastest rates exhibited by the PGs. In general, amounts of radioactivity found in antimesometrial, mesometrial and lateral portions of the uterine wall, or in implantation and interimplantation areas did not differ, but more was found in the endometrium than the myometrium. PGF2 alpha was translocated unmetabolized to the external medium, while only two-thirds of the PGE2 was translocated unchanged, and one-third converted to PGF2 alpha. It is concluded that the rabbit uterus shows some selectivity in handling PGs in relation to stage of pregnancy.     

The role of major histocompatibility complex molecules in luteal function

Background

Turkey reproduction is by artificial insemination using pooled semen so there is interest in storing semen. Fertilizing capacity declines after six hours storage, possibly due to poor sperm mobility. Prostaglandins (PG) affect mammalian sperm motility, but avian sperm has not been widely studied. For this study, levels of PG E1, E2, and F2 alpha in turkey seminal plasma and sperm extract, and effects of cyclooxygenase (COX) inhibitors on sperm mobility were determined.

Methods

Seminal Plasma and sperm extract PG E1, E2, and F2 alpha, from 1.0 mL pooled semen, were measured by ELISA. In Trial 1, PG were determined from 122 wk old toms (n = 4). Trial 2 used 36 wk old toms (n = 7). For Trial 3, PGE2 only was measured from 48 wk (n = 6) and 154 wk old toms (n = 3). The effects of non-specific COX inhibitors indomethacin, diclofenac, tolmetin, or aspirin (n = 10), or specific COX-1 or COX-2 inhibitors (n = 3) on sperm mobility were measured (Accudenz swim-down test).

Results

Seminal plasma PG (pg/mL) in Trials 1 and 2, respectively, were 185.2 ± 88.4 and 187.2 ± 33.7 for PGE1; 141.4 ± 43.1 and 100.4 ± 14.6 for PGF2 alpha; and 431.0 ± 155.1 for PGE2 (Trial 1 only). Sperm extract PG (pg/10 billion cells) in Trials 1 and 2, respectively, were 215.1 ± 38.1 and 208.9 ± 41.5 for PGE1; 133.7 ± 51.7 and 49.8 ± 8.3 for PGF2 alpha; and 52.3 ± 8.6 for PGE2 (Trial 1 only). In Trial 3, seminal plasma PGE2 (pg/mL) in older versus younger males was 1097.9 ± 99.3 versus 853.2 ± 144.6 and sperm extract PGE2 (pg/10 billion cells) was 208.0 ± 56.1 versus 102.4 ± 14.8. Cyclooxygenase inhibitors (0.001 to 10 mM) decreased sperm mobility: indomethacin 15 to 100%; diclofenac 4 to 100%; tolmetin 27 to 74%; aspirin (tested at 0.01 to 15 mM) 22 to 42%; resveratrol (COX-1) and NS-398 (COX-2), both tested at 0.1 to 10 mM, 38 to 98% and 44 to 85%, respectively.

Conclusion

These results indicate that PG are present in turkey seminal plasma and sperm, and COX inhibitors decrease turkey sperm mobility.     

Prostaglandins can modify gamma-radiation and chemical induced cytotoxicity and genetic damage in vitro and in vivo

The effect of prostaglandin E1, E2, and F2 alpha on gamma-radiation, benzo(a)pyrene and diphenylhydantoin-induced cytotoxicity in vivo and genotoxicity in vitro was investigated. Prostaglandin E1 prevented both cytotoxic and genotoxic actions of all the three agents, where as both PGE2 and PGF2 alpha were ineffective. In fact, it was seen that both PGE2 and PGF2 alpha are genotoxic by themselves. Gamma-linolenic acid and dihomogamma-linolenic acid, the precursor of PGE1 were also as protective as that of PGE1, where as arachidonic acid, the precursor of 2 series PGs, has genotoxic actions to human lymphocytes in vitro. These results suggest that prostaglandins and their precursors can determine the susceptibility of cells to cytotoxic and genotoxic actions of chemicals and radiation. This study is particularly interesting since, it is known that some tumor cells contain excess of PGE2 and PGF2 alpha and many carcinogens can augment the synthesis of 2 series of PGs.     

Prostaglandin production by corpora lutea of rhesus monkeys: characterization of incubation conditions and examination of putative regulators

Prostaglandins (PGs) are produced by the corpus luteum (CL) of many domestic and laboratory species and may play a role in CL regulation. The production of PGs by luteal tissue of the rhesus monkey has yet to be clearly elucidated. The production of PGE2, PGF2 alpha, and 6-keto-PGF1 alpha by CL from rhesus monkeys and the incubation conditions (time and cell number) that permit assessment of their synthesis were examined. CL (n = 3 per characterization) were surgically removed from nonpregnant monkeys during the mid-luteal phase of the menstrual cycle (approximately 8-10 days after ovulation). Luteal tissue was dissociated and the cells were incubated at varying concentrations for increasing periods of time at 37 degrees C. Subsequent to defining incubation conditions, various exogenous factors were examined for their potential to modify PG production. Indomethacin, calcium ionophore, human chorionic gonadotropin (hCG), estradiol-17 beta (E2), progesterone (P), testosterone (T), dihydrotestosterone (DHT), and 1-4-6 androstatriene-3, 17-dione (ATD) were incubated with luteal cells in increasing doses. PG and P concentrations in the medium were determined by radioimmunoassay. PGs in the medium after 6 h incubation were detectable at all cell concentrations tested (50,000, 100,000, 200,000 cells/tube). Concentrations of PGs and P increased with cell number (p less than 0.05). Luteal cells (50,000 cells/tube) were incubated for times of 0-24 h. Concentrations of P, PGE2, and PGF2 alpha in the medium were relatively low prior to incubation (0 h), increased (p less than 0.05) linearly within the first 6-12 h, and plateaued through the remaining 24 h.(ABSTRACT TRUNCATED AT 250 WORDS)     

Phytoestrogens modulate prostaglandin production in bovine endometrium: cell type specificity and intracellular mechanisms

Prostaglandins (PGs) are known to modulate the proper cyclicity of bovine reproductive organs. The main luteolytic agent in ruminants is PGF2alpha, whereas PGE2 has luteotropic actions. Estradiol 17beta (E2) regulates uterus function by influencing PG synthesis. Phytoestrogens structurally resemble E2 and possess estrogenic activity; therefore, they may mimic the effects of E2 on PG synthesis and influence the reproductive system. Using a cell-culture system of bovine epithelial and stromal cells, we determined cell-specific effects of phytoestrogens (i.e., daidzein, genistein), their metabolites (i.e., equol and para-ethyl-phenol, respectively), and E2 on PGF2alpha and PGE2 synthesis and examined the intracellular mechanisms of their actions. Both PGs produced by stromal and epithelial cells were significantly stimulated by phytoestrogens and their metabolites. However, PGF2alpha synthesis by both kinds of cells was greater stimulated than PGE2 synthesis. Moreover, epithelial cells treated with phytoestrogens synthesized more PGF2alpha than stromal cells, increasing the PGF2alpha to PGE2 ratio. The epithelial and stromal cells were preincubated with an estrogen-receptor (ER) antagonist (i.e., ICI), a translation inhibitor (i.e., actinomycin D), a protein kinase A inhibitor (i.e., staurosporin), and a phospholipase C inhibitor (i.e., U73122) for 0.5 hrs and then stimulated with equol, para-ethyl-phenol, or E2. Although the action of E2 on PGF2alpha synthesis was blocked by all reagents, the stimulatory effect of phytoestrogens was blocked only by ICI and actinomycin D in both cell types. Moreover, in contrast to E2 action, phytoestrogens did not cause intracellular calcium mobilization in either epithelial or stromal cells. Phytoestrogens stimulate both PGF2alpha and PGE2 in both cell types of bovine endometrium via an ER-dependent genomic pathway. However, because phytoestrogens preferentially stimulated PGF2alpha synthesis in epithelial cells of bovine endometrium, they may disrupt uterus function by altering the PGF2alpha to PGE2 ratio.     

Prostaglandin E and E2 alpha secretion by glandular and stromal cells of the pig endometrium in vitro: effects of estradiol-17 beta, progesterone, and day of pregnancy.

Prostaglandins (PGs) are believed to play important roles in the establishment of pregnancy. Glandular and stromal cells were isolated from pig endometrium on days 11 through 19 of pregnancy and cultured in the presence of estradiol-17 beta (E2) and progesterone (P4) to determine the effect of day of pregnancy and steroids on the secretion of PGE and PGF2 alpha. Estradiol at concentrations between .01 and 1 microM did not affect PGE and PGF2 alpha secretion into the medium by glandular and stromal cells. Progesterone (.1 microM) suppressed (P less than .001) PGE and PGF2 alpha production from both cell types. Glandular cells secreted more (P less than .01) PGF2 alpha than PGE, whereas stromal cells collected on days 11, 12, 13, and 19 secreted more (P less than .05) PGE than PGF2 alpha. Stromal cells isolated from tissues collected on day 13 of pregnancy produced PGs with higher (P less than .01) PGE:PGF2 alpha ratio than those from tissues harvested on other days of pregnancy. Glandular cells isolated from tissues collected on days 13 and 19 and stromal cells isolated from tissue collected on day 13 of pregnancy secreted more (P less than .05) PGE and PGF2 alpha than cells isolated on other days of pregnancy. We conclude that: 1) P4 has a suppressing effect on PG secretion; 2) endometrial glandular and stromal cells each produce a unique profile of PGs; and 3) endometrial cells harvested on different days of pregnancy secrete different amounts of PGE and PGF2 alpha.     

Relationship of cAMP and calcium messenger systems in prostaglandin-stimulated UMR-106 cells

The effect of prostaglandins (PG) on free cytosolic calcium concentrations [( Ca2+]i) and cAMP levels was studied in the osteosarcoma cell line UMR-106. PGF2 alpha and PGE2, but not 6-keto-PGF1 alpha, induced an increase in [Ca2+]i which was mainly due to Ca2+ release from intracellular stores. The EC50 for PGF2 alpha was approximately 7 nM, whereas that for PGE2 was approximately 1.8 microM. Maximal doses of PGF2 alpha increased [Ca2+]i to higher levels than PGE2. Both active PGs also stimulated phosphatidylinositol turnover in UMR-106 cells. The effects of the two PGs were independent of each other and appear to involve separate receptors for each PG. PGE2 was a very potent stimulator of cAMP production and increased cAMP by approximately 80-fold with an EC50 of 0.073 microM. PGF2 alpha was a very poor stimulator of cAMP production; 25 microM PGF2 alpha increased cAMP by 5-fold. The increase in cellular cAMP levels activated a plasma membrane Ca2+ channel which resulted in a secondary, slow increase in [Ca2+]i. High concentrations of both PGs (10-50 microM) inhibited this channel independent of their effect on cAMP levels. Pretreatment of the cells with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate inhibited the PG-mediated increase in phosphatidylinositol turnover and the increase in [Ca2+]i. However, pretreatment with 12-O-tetradecanoyl-13-acetate had no effect on the PGE2-mediated increase in cAMP. The latter finding, together with the dose responses for PGE2-mediated increases in [Ca2+]i and cAMP levels, suggests the presence of two subclasses of PGE2 receptors: one coupled to adenylate cyclase and the other to phospholipase C. With respect to osteoblast function, the cAMP signaling system is antiproliferative, whereas the Ca2+ messenger system, although having no proliferative effect by itself, tempers cAMP's antiproliferative effect.     

The urinary excretion of prostaglandins and thromboxane B2 in healthy volunteers: a study in males and females, and on the influence of seminal fluid contamination

Radioimmunoassay measurements of prostaglandins (PGs) E2, F2 alpha, 6-keto-PGF1 alpha and thromboxane (Tx) B2 in 24 h urine specimens from a male and a female healthy volunteer on several consecutive days revealed a dramatic increase of PGE2, PGF2 alpha, 6-keto-PGF1 alpha on days, upon which they had sexual intercourse; only TxB2 remained stable. Furthermore, the PGE2/PGF2 alpha ratio rose to values greater than 0.5 on days with sexual intercourse. This was found to be due to contamination of the urine samples by seminal fluid. Two 24 h urine samples from each of 26 healthy male and female volunteers (HV) revealed higher (p less than 0.01) mean PGE2 and PGF2 alpha values in males than in females. The results show that the interpretation of the urinary PG excretion as a measure of renal PG synthesis should be considered carefully, and that a PGE2/PGF2 alpha ratio greater than 0.5 indicates probable seminal contamination of urine.     

Role of progesterone in regulating uteroovarian venous concentrations of PGF2 alpha and PGE2 during the estrous cycle and early pregnancy in ewes

The role of progesterone in regulation of uteroovarian venous concentrations of prostaglandins F2 alpha(PGF2 alpha) and E2 (PGE2) during days 13 to 16 of the ovine estrous cycle or early pregnancy was examined. At estrus, ewes were either mated to a fertile ram or unmated. On day 12 postestrus, ewes were laparotomized and a catheter was inserted into a uteroovarian vein. Six mated and 7 unmated ewes received no further treatment. Fifteen mated and 13 unmated ewes were ovariectomized on day 12 and of these, 7 mated and 5 unmated ewes were given 10 mg progesterone sc and an intravaginal pessary containing 30 mg of progesterone. Uteroovarian venous samples were collected every 15 min for 3 h on days 13 to 16 postestrus. Mating resulted in higher mean daily concentrations of PGE2 in the uteroovarian vein than in unmated ewes. Ovariectomy prevented the rise in PGE2 with day in mated ewes but had no effect in unmated ewes. Progesterone treatment restored PGE2 in ovariectomized, mated ewes with intact embryos. Mating had no effect on mean daily concentrations of PGE2 alpha or the patterns of the natural logarithm (1n) of the variance of PGF2 alpha. Ovariectomy resulted in higher mean concentrations and 1n variances of PGF2 alpha on day 13 and lower mean concentrations and 1n variances of PGF2 alpha on days 15 and 16. Replacement with progesterone prevented these changes in patterns of mean concentrations and 1n variances of PGF2 alpha following ovariectomy. It is concluded that progesterone regulates the release of PGF2 alpha from the uterus, maintaining high concentrations while also preventing the occurrence of the final peaks of PGF2 alpha which are seen with falling concentrations of progesterone. This occurs in both pregnant and non-pregnant ewes. Progesterone is also needed to maintain increasing concentrations of PGE2 in mated ewes.     

Regulation of avidin accumulation by prostaglandins in chick oviduct culture

Regulation of avidin accumulation by prostaglandins (PGs) and their inhibitors was studied in chick oviduct organ culture. Avidin was induced neither by progesterone nor PGF2 alpha in the oviduct of immature chicks. By progesterone and PGs, a high avidin synthesis was induced when the chicks received diethylstilbestrol (DES) for 7 days. Enhanced avidin production was observed by PGF2 alpha, PGE1 and PGE2, whereas PGA2 and PGB2 had a slight inhibitory effect and PGA1 and PGB1 had no effect on avidin production. PGF2 alpha was most effective at a concentration of 10-20 micrograms/ml. The effects of progesterone and PGF2 alpha were not additive. Mefenamic acid, at concentrations of 40 and 60 micrograms/ml, inhibited 50 and 85%, respectively, of the avidin synthesis induced by progesterone, whereas the inhibition of the total protein synthesis was only 20%, and this only by the higher concentration of the drug. Tolfenamic and meclofenamic acid were also inhibitory in the case of progestin-induced avidin synthesis. These studies indicate that the PGs (F2 alpha, E1 and E2) might be involved in the avidin induction in the chick differentiated oviduct. The specific inhibition of the progesterone-dependent avidin synthesis by the PG inhibitors suggests that PGs may be connected with the progesterone action in the oviduct. We propose that the avidin synthesis by the chick oviduct might be considered as a model system for studying PG effects on the synthesis of a specific protein.     

Bovine placental prostaglandin synthesis: principal cell synthesis as modulated by the binucleate cell

Bovine placentomes were collected during late gestation, prepartum, and immediately postpartum. Postpartum tissues were collected prior to fetal placental release. A procedure for separating fetal placental principal cells from fetal binucleate cells (BNC) was developed. Dispersed fetal placental cells (mixed types), principal cells, and BNC were each examined for their ability to produce prostaglandins (PGs) from arachidonic acid (AA) and to metabolize prostaglandin E2 (PGE2) and prostaglandin F2 alpha (PGF2 alpha) in vitro. Dispersed fetal placental cells obtained prepartum produced predominantly PGs of the E series (PGEs) from AA (p less than 0.05). PGE synthesis predominated (p less than .05) in cells from postpartum tissue if the fetal placental membranes were subsequently retained, whereas synthesis of PGs of the F series (PGFs) predominated (p less than 0.05) if the fetal membranes were subsequently released. Principal cells were the primary source of fetal placental PG synthesis from AA (p less than 0.05). BNC exhibited a lesser ability to synthesize PGs from AA (p less than 0.05), but were able to convert PGF2 alpha to PGE2. Dispersed fetal placental cells exhibited greater ability to convert PGF2 alpha to PGE2 (p less than 0.05) than did the separated cells. These data suggest the function of a two-cell system within the fetal villi such that the BNC modulate the output of principal cell PG synthesis and/or metabolism.     

Radioimmunoassay measurement of ACTH-facilitated PGE2 and PGF2alpha release from isolated cat adrenocortical cells.

Prostaglandin (PG) biosynthesis by trypsin-dispersed cat adrenocortical cells was studied by radioimmunoassay (RIA). Parallel assays of incubation media using PGF2alpha and PGF1alpha antisera established that PGF2alpha is the primary PGF released by feline cortical cells. Following the reduction of PGE to PGF with sodium borohydride (NaBH4) these same two antisera were also used to identify PGE2 as the primary PGE released. RIA using a PGE antiserum confirmed the presence of PGE in the incubation medium. Steroidogenic concentrations of ACTH (50-250muU) enhanced PGE and PGF release, and indomethacin suppressed the ACTH-facilitated release. These studies provide additional evidence for ACTH-induced PG synthesis by feline cortical cells, and support the hypothesis that PGs play some role in the steroidogenic action of ACTH.     

Regional and species differences in endogenous prostaglandin biosynthesis by brain homogenates.

Endogenously formed prostaglandins (PGs) D2, E2 and F2 alpha were determined in homogenates of brain regions from rat, guinea-pig, rabbit and cat, using gas-chromatography-mass spectrometry. The main PGs formed in the brain regions of the rat were PGD2, in the guinea-pig PGD2 and PGF2 alpha, in the rabbit PGF2 alpha and in the cat PGE2. Brain regions from the same animal species showed the same pattern of PG formation. They varied, however, in the amount of total PGs formed, the limbic system and the cerebral cortex being highest and cerebellum lowest.     

Effective use of rabbit gastric antral mucosal slices in prostaglandin synthesis and metabolism studies

Intact slice preparations of rabbit stomach (antral mucosa, corporal mucosa, antral muscle and corporal muscle) were incubated and the released prostaglandins (PGs) were measured by reverse-phase high-performance liquid chromatography using 9-anthryldiazomethane for derivatization. With respect to total PG production, the highest amounts were generated by antral mucosal slices. Antral mucosal slices produced PGE2, 6-keto PGF1 alpha, thromboxane B2, PGF2 alpha and PGD2 (in descending order of magnitude) and possessed a high capacity for producing 13,14-dihydro-15-keto derivatives of both PGE2 and PGF2 alpha. Studies utilizing aspirin, EGTA or Ca2+ revealed that PG release by antral mucosal slices in the present in vitro system reflects a composite of the activities of phospholipase A3, PG cyclooxygenase and PG-metabolizing enzymes. These results show that antral mucosal slices will be useful in physiological and pharmacological studies on PG synthesis and metabolism of the stomach.     

Effects of conjugated linoleic acid on prostaglandins produced by cells isolated from maternal intercotyledonary endometrium, fetal allantochorion and amnion in late pregnant ewes

The anticarcinogenic properties of conjugated linoleic acid (CLA) are, at least partially, attributed to its ability to interrupt the n-6 polyunsaturated fatty acid (PUFA) metabolic pathway for the biosynthesis of eicosanoids, including prostaglandins (PG). Both PGE(2) and PGF(2alpha) play key roles in parturition. In the present study, we compared the effects of CLA (a mixture of cis- and trans-9, 11- and -10, 12-octadecadienoic acid) and linoleic acid (LA) on PG production by cells isolated from maternal intercotyledonary endometrium, fetal allantochorion and amnion from late pregnant ewes. The results demonstrated that supplementation of LA and CLA significantly affected both the proportions and the amounts of PGs produced by all three tissue types. The ability of the uterus and placenta to respond to oxytocin (OT, endometrium only) and lipopolysaccharide (LPS) was also affected. LA inhibited PGE(2) and PGF(2alpha) production in the absence or presence of either oxytocin or LPS. In endometrial cells with or without oxytocin or LPS, CLA dose-dependently suppressed PGF(2alpha) generation, whereas low doses of CLA (20 microM) increased PGE(2) generation. Supplementation with CLA therefore increased the PGE(2)/PGF(2alpha) ratio in the endometrial cells. These results suggest that dietary supplementation of LA or CLA may affect both the initiation and progression of parturition.     

Prostaglandin release by zygotes and endometria of pregnant rabbits

When 4-day rabbit zygotes were incubated for 1 h at 37 degrees C in vitro, very little prostaglandin (PG) was released into the medium, and the concentration of PGs in the zygotes after incubation was also low. The release of prostaglandin E (PGE) and prostaglandin F (PGF) into the medium, and their concentration in the zygotes after incubation, increased sharply on Days 6 and 7 of pregnancy, reaching, by Day 7, values close to 200 ng of each PG released in 1 h per mg of protein. By contrast, endometrial samples on Days 4 and 5 of pregnancy released more PGF and less PGE than the zygotes of the same ages on a per mg of protein basis, and on Days 6 and 7, less of both PGs. Furthermore, endometrial concentrations of PGs after incubation, except for PGF on Day 4, were always lower than values for zygotes. Endometrial concentrations of PGs on Day 6 were lower before than after incubation. Although there was a slight upward trend in PG release by endometrial samples with increasing length of pregnancy, the changes were minimal and, in the case of PGE, none of the mean values exceeded 1 ng per mg of protein. In 7-day blastocysts, high levels of both PGF and PGE were found in the blastocoelic fluid, and these did not change during the 1-h incubation. The release of PGF and PGE during in vitro incubation of ruptured and washed Day 6 blastocysts was stimulated by arachidonic acid, and that of PGF, but not PGE, inhibited by indomethacin. The release of PGE, but not of PGF, from Day 6 blastocysts was inhibited by low temperature, and the same conditions inhibited release of both PGF and PGE from endometrial cell suspensions. It seems that both blastocysts and endometria have capability to synthesize PGs, the blastocysts being particularly active in this regard on Days 6 and 7 of pregnancy. It is hypothesized that, in vivo, Day 6 and 7 blastocysts release large quantities of PGs which trigger some of the local endometrial changes associated with pregnancy.     

Maturation-related variations in prostaglandin and fatty acid content of ovary in the kuruma prawn (Marsupenaeus japonicus)

Total lipid, fatty acids and prostaglandins (PGF(2 alpha) and PGE(2)) in the ovary of kuruma prawns (Marsupenaeus japonicus) were measured during ovarian development. The level of ovarian total lipid increased with an increase in the gonad-somatic index (GSI). No significant difference was found in fatty acid composition among different stages of ovarian development. However, the content of arachidonic acid (precursor of PG(2)), but not eicosapentanoic acid (precursor of PG(3)), was significantly lower at stages I and II than at stage V (P<0.01). When ovarian PGF(2 alpha) and PGE(2) levels were plotted against GSI, no correlation was found in either PG. However, in terms of ovarian developmental stages, the level of ovarian PGs was high (approx. 20 pg/mg) at stage I, followed by marked decreases at stages IV and V (PGF(2 alpha), P<0.01) and stage IV (PGE(2), P<0.01). These results suggest that ovarian PGs and arachidonic acid are deeply involved in ovarian maturation in kuruma prawns.     

Receptors for prostaglandins F2 alpha and E2 in ovine corpora lutea during maternal recognition of pregnancy.

Plasma membrane receptors for prostaglandins (PG) F2 alpha and E2 were quantified in ovine corpora lutea obtained from nonpregnant and pregnant ewes on Days 10, 13, and 15 post-estrus, and from additional ewes on Days 25 and 40 of pregnancy. Regardless of reproductive status or day post-estrus, concentrations of luteal receptors for PGF2 alpha were 7- to 10-fold greater than those for PGE2. In pregnant ewes the concentration of receptors for PGF2 alpha was highest on Day 10 (35.4 +/- 2.8 fmol/mg) and lowest on Day 25 (22.3 +/- 2.5 fmol/mg). A difference in the concentration of luteal receptors for PGF2 alpha between pregnant and nonpregnant ewes was apparent only on Day 15 post-estrus, at which time the concentration of receptors for PGF2 alpha was higher in pregnant ewes than in nonpregnant ewes (27.1 +/- 2.7 vs. 17.7 +/- 2.7 fmol/mg). Concentrations of receptors for PGE2 in pregnant ewes were similar (p > 0.05; 2.8 +/- 0.3 to 3.7 +/- 0.2 fmol/mg) between Days 13 and 40 but were higher (p < 0.05) than in corpora lutea obtained from nonpregnant ewes on Days 10 (5.0 +/- 0.4 vs. 4.1 +/- 0.2 fmol/mg) and 15 (3.7 +/- 0.2 vs. 2.0 +/- 0.4 fmol/mg) post-estrus. Although concentrations of receptors for both PGF2 alpha and PGE2 were lowest in corpora lutea obtained from nonpregnant ewes on Day 15, this was not due to luteal regression since the weights and concentrations of progesterone in corpora lutea on Day 15 were not lower than those for corpora lutea obtained on Days 10 and 13.(ABSTRACT TRUNCATED AT 250 WORDS)