Prostaglandin and tumor necrosis factor levels in early wound inflammatory fluid: effects of parenteral omega-3 and omega-6 fatty acid administration

Monokines are important mediators of wound healing. Specifically, the proportions of proinflammatory (tumor necrosis factor and PGE2) and antiinflammatory (PGF2 alpha) monokines may modulate its early phases. Using a polyvinyl alcohol sponge model of rat wounding, the authors determined the temporal changes in the levels of monokines in wound inflammatory fluid, and examined whether dietary manipulation for 6 days with the precursors (omega 6 fatty acids) and inhibitors (fish oil omega 3 fatty acids) of the prostaglandin-2 series influenced monokine composition of wound fluid. For 3 days before the wounding, adult rats received isocaloric, isovolemic, and isonitrogenous total parenteral nutrition (TPN), in which lipids supplied either 35% (Intralipid [IL] or fish oil emulsion [FO]) or 8% (minimal essential fatty acid; EFA) of the total calories. Control rats received isocaloric enteral chow. The controls were studied at 24, 48, 72, and 96 hours, and the experimentals at 72 hours after wounding. Cell counts were performed, and cell-free fluid was analyzed for PGE2, PGF2 alpha, and TNF. In control rats, the total WBC count was highest at 24 to 48 hours, and decreased significantly by 96 hours. The percentage of mononuclear cells progressively increased throughout the 96 hours, and the total mononuclear cell count peaked at 72 hours. The TNF and prostaglandin levels were highest at 24 hours; these decreased rapidly by 72 hours. At all time-points, the levels of PGE2 remained higher than those of PGF2 alpha.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of prostaglandin E2 and F2 alpha on the skeleton of osteopenic ovariectomized rats

This article contains the histomorphometric evaluation of the effects of prostaglandin F2 alpha (PGF2 alpha) on cancellous bone from the lumbar vertebra and cortical bone from the tibial shaft of ovariectomized, osteopenic rats. These effects were then compared with those of prostaglandin E2 (PGE2). Three-month-old rats were either ovariectomized (ovx) or sham-ovx. Then, either PGF2 alpha or PGE2 in doses of 1 and 3 mg/kg/day was given subcutaneously for 21 days at 150 days post ovx. Histomorphometric analysis was performed separately on both the primary and secondary spongiosae of the fourth lumbar vertebral bodies (LVB) and on tibial shafts. The ovx rats exhibited osteopenia in both primary (-23% to -37%) and secondary (-20%) spongiosae of the LVB, but not in the tibial shafts at 150 and 171 days post ovx. In the LVB, PGE2 in doses of 1 or 3 mg/kg/day for 21 days restored trabecular bone volume to the levels of sham-ovx controls in the primary spongiosa. However, in the secondary spongiosa, the treatments only thickened the trabeculae. The effects of the PGF2 alpha treatment were similar to those of the PGE2 in both the primary and the secondary spongiosae. While both PGF2 alpha and PGE2 treatments stimulated bone formation in the LVB as indicated by the increases in labeled perimeter, tissue and bone area-based bone formation rates, PGE2 is about 10 times more potent than PGF2 alpha in these effects. The PGE2 treatment also elevated activation frequency in the LVB, while the PGF2 alpha treatment did not. The treatments differed in that PGE2 at these dose levels did not alter the eroded surface in the LVB while PGF2 alpha decreased it significantly. Thus, the increase of the ratio of labeled to eroded perimeter in the LVB in PGF2 alpha-treated animals was much more than that in PGE2-treated animals. In the tibial shafts, PGE2 in doses of 1 and 3 mg/kg/day produced new marrow trabeculae in 2 of 6 and 3 of 6 of the ovx rats. However, no new trabecula was found in PGF2 alpha-treated tibial shafts. Higher doses of PGE2 also increased periosteal labeled perimeter, MAR, and BFR/BS, while PGF2 alpha did not produce any significant change in these parameters. Both PGE2 and PGF2 alpha in doses of 1 and 3 mg/kg/day increased the labeled perimeter, MAR and BFR/BS and decreased the eroded perimeter in the endocortical surface. We concluded that both PGF2 alpha and PGE2 in doses of 1 and 3 mg/kg/day for 21 days exhibited anabolic bone effects. The effects were mostly confined to an increase in trabecular volume in the primary spongiosa of the LVB and in the endocortical surface of tibial shafts. The tissue level mechanism behind this appears to be that PGE2 and PGF2 alpha can both stimulate osteoblast recruitment and activity. Overall, we found PGE2 to be more potent than PGF2 alpha at the same dose level at the endocortical surface. Furthermore, new marrow trabecular bone formed only after PGE2 treatment. PGF2 alpha differed from PGE2 by significantly reducing the trabecular eroded surface in ovx rats.     

Bronchial reactivity to prostaglandins F2alpha, E2, and histamine in different types of asthma

Bronchial reactivity to prostaglandins F2alpha (PGF2alpha), E2 (PGE2) and histamine has been studied in 27 patients with aspirin-sensitive asthma and in 28 asthmatics without this sensitivity. Of the latter group, 13 patients had atopic, 9 infectious, and 6 mixed type of asthma. Atopic patients were characterized by vivid reactivity to low doses of both PGF2alpha and histamine. In patients with infectious asthma significantly higher doses of both PGF2alpha and histamine were necessary to induce bronchoconstriction as compared to atopics. Aspirin-sensitive patients responded quickly with bronchial spasm to similar doses of histamine as atopics, but tolerated significantly higher doses of PGF2alpha. There was no difference in reactivity to PGF2alpha between patients with aspirin sensitivity and those with infectious asthma. 5 and 10 min after administration of 60 microgram PGE2 significantly better improvement in ventilation occurred in aspirin-sensitive patients than in those of either atopic or infectious groups. The results obtained point to differences in bronchial reactivity to prostaglandins and histamine depending on type of asthma and severity of its symptoms.     

Radioimmunoassay of prostaglandins E1, E2, and F2alpha in unextracted plasma, serum and myocardium

A radioimmunoassay procedure for the determination of PGE1, PGE2, and PGF2alpha is presented. The procedure involves the pre-precipitation of each prostaglandin specific antiserum with the precipitating antisera (ARGG), and the use of these antisera mixtures in assaying for PGE1, PGE2, and PGF2alpha. Applicability of the methods to unextracted plasma, serum and myocardial homogenate has been demonstrated through tests of specificity, recovery, reproducability and parallelism. A mathematical correction for cross-reactivity between PGE1 and PGE2, and their opposing antisera is given. To demonstrate the utility of the methodology in differentiation of experimental variables, prostaglandin concentrations in unincubated serum, incubated serum, and the rate of prostaglandin production in serum of dogs are given.     

Effects of 16,16-Dimethyl-trans-delta 2-PGE1 methyl ester (ONO-802) on uterine, placental and ovarian circulation (author's transl)

Doses of the drugs which produce uterine contraction were given intravenously to various species of animals. Placental and ovarian circulations were measured by the thermocouple method and/or microangiography. Uterine arterial blood flow (UABF) was measured by the electromagnetic flowmeter. Both placental blood flow (PBF) and UABF decreased with the administration of ONO-802, PGE1 or PGF2 alpha to to rabbits and dogs. Oxytocin and noradrenaline also decreased PBF in rabbits. ONO-802 or PGE1 lowered arterial blood pressure (BP) in rats, rabbits and dogs. PGE2 alpha elevated BP in rats and dogs and lowered it in rabbits. Oxytocin produced no changes in PB while noradrenaline elevated BP in rabbits. Ovarian blood flow in pregnant rabbits was reduced by ONO-802, PGE1 or PGF2 alpha. Little influence was seen with oxytocin. Regarding the luteal microvasculature in pregnant rats, ONO-802, PGF2 alpha and noradrenaline exhibited vasoconstricting effects. PGF2 alpha induced abortion and decreased plasma progesterone levels. These results suggest that the inhibitory effects of ONO-802 on the uterine and placental circulation are strongly influenced by the uterine contractile effect and that the inhibitory effect on the ovarian circulation in rats is one of pharmacological effects not concerned with the abortifacient or luteolytic effect.     

PGE2 attenuates PGF2 alpha-induced increases in free intracellular calcium in ovine large luteal cells

When ovine large luteal cells are placed in culture and exposed to PGF2 alpha, there is a rapid and sustained increase in the concentration of free intracellular calcium which is believed to play a major role in the luteolytic and cytotoxic effects of PGF2 alpha. Since administration of exogenous PGE2 can prevent spontaneous and PGF2 alpha-induced luteolysis in vivo, and the cytotoxic effects of PGF2 alpha on large luteal cells in vitro, the objective of this study was to determine if one mechanism by which PGE2 acts is to attenuate increases in free intracellular calcium induced by PGF2 alpha. At concentrations of 10 nM or greater, PGF2 alpha caused a significant and sustained increase in free intracellular calcium in large luteal cells. Similarly, PGE2 also induced increases in free intracellular calcium but required doses 20-fold greater than PGF2 alpha. When PGE2 (1, 10 or 100 nM) was incubated with PGF2 alpha (100 nM) increases in free intracellular calcium induced by PGF2 alpha were attenuated (P < 0.05) when measured 5 min, but not at 30 min, after initiation of treatment. The observed decrease in the concentration of free intracellular calcium at 5 min in response to PGF2 alpha was the result of fewer cells responding to PGF2 alpha. In addition, the concentrations of free intracellular calcium attained in the cells that did respond was reduced 25% compared to cells treated with PGF2 alpha alone. Thus, part of the luteal protective actions of PGE2 appears to involve an inhibition of the early (5 min) increase in free intracellular calcium induced by PGF2 alpha.     

Regulation of cyclooxygenase-2 and prostaglandin F synthase gene expression by steroid hormones and interferon-tau in bovine endometrial cells

Estradiol (E2) and progesterone are responsible for regulating PG synthesis in the endometrium during the estrous cycle and interferon-tau (IFN-tau) alters PG synthesis during early pregnancy in ruminants. In this study, we examined the effects of these steroid hormones and recombinant bovine IFN-tau (rbIFN-tau) on PG production and on cyclooxygenase-2 (COX-2) and PG F (PGF) synthase (PGFS) gene expression in isolated endometrial cells. E2 decreased both PGF2alpha and PG E2 (PGE2) whereas progesterone increased PGF2alpha secretion in epithelial cells. Steroid hormones had no effect on PG production in stromal cells. rbIFN-tau attenuated both PGF2alpha and PGE2 production in epithelial cells and enhanced their production, and the ratio of PGE2 to PGF2alpha, in stromal cells. Northern blot analysis showed that E2 and rbIFN-tau decreased COX-2 messenger RNA (mRNA) levels in epithelial cells. Conversely, rbIFN-tau increased COX-2 mRNA in stromal cells. Furthermore, rbIFN-tau decreased PGFS mRNA in both cell types and this was associated with the increase in PGE2/PGF2alpha ratio. These results show that the regulation of PG synthesis by steroid hormones is different in endometrial epithelial and stromal cells in vitro. The attenuation of PGF2alpha secretion from epithelial cells and increased PGE2 production in stromal cells by rbIFN-tau are modulated by steroid hormones.     

Myocardial production of prostaglandins: its role in atrial natriuretic peptide release

In recent years, considerable evidence has been accumulated on prostaglandins (PG) in modulating atrial natriuretic peptide (ANP) release. In the current study we investigated whether eicosanoids promote isoproterenol-induced ANP secretion from superfused rabbit sliced atria. Inclusion of the cyclooxygenase inhibitor indomethacin (10 mumol) to the superfusing medium abolished isoproterenol-induced ANP release. Next, PGE2, but not PGF2 alpha or PGI2 (10 mumol), increased ANP release. Furthermore, isoproterenol-induced PGE2 formation was fully attenuated by indomethacin. Dibutyl-cAMP (0.5 mmol) had no effect on PGE2 formation, and the protein kinase A (PKA) inhibitor H89 (20 mumol) did not alter isoproterenol-induced PGE2 formation. On the other hand, indomethacin led to a significant decrease in isoproterenol-induced cAMP production. In addition, PGE2 enhanced basal cAMP concentration in superfusates. Superfusion of sliced atria by forskolin (10 mumol) or by dibutyl-cAMP (0.5 mmol) produced a significant rise in ANP release. Finally, H89 was ineffective on basal ANP release but abolished the increase of ANP release in response to isoproterenol or to PGE2. We conclude that: the effect of isoproterenol on ANP release is sensitive to indomethacin and H89; PGE2, but not PGE2 alpha or PGI2, increases ANP release; isoproterenol promotes myocardial PGE2 formation independently of adenylate cyclase and PKA activation pathways; and PGE2-induced ANP release is mediated by cAMP production and subsequent PKA activation. These results suggest that isoproterenol-induced ANP release appears to be mediated at least partly by PGE2 with underlying cAMP formation and PKA activation.     

Factor XI activity and factor XI antigen in homozygous and heterozygous factor XI deficiency

Artificially synthesized prostaglandins (PGE1, PGE2, PGF1alpha, and PGF2alpha) were found, using Boyden's chamber, to induce significant migration of polymorphonuclear leukocytes (PMNs) of the rabbit; PGF2alpha had greater effects than PGE1 or E2. A typical dose dependent relationship was found between the PMNs migration and PGF2alpha concentrations. Indomethacin pretreatments of rabbits did not significantly alter the PMNs migration indicating that PGs synthetized in vivo was not involved in the migration. PGF2alpha was placed in the lower compartment opposite to PMNs and also in the upper compartment together with PMNs. No significant difference was found in the number of migrated PMNs between the two experimental conditions. PGs diffusion occurred across the millipore filter separating the two compartments where the concentrations were almost equal at the end of 3 hours incubation. It was thus concluded that PGs effects are to induce random PMNs movements rather than to initiate chemotactic directional migration.     

The subtype-2 (AT2) angiotensin receptor regulates renal cyclic guanosine 3', 5'-monophosphate and AT1 receptor-mediated prostaglandin E2 production in conscious rats

The renal effects of angiotensin II(AII) are attributed to AT1 receptors. In contrast, the function of renal AT2 receptors in unknown. Using a microdialysis technique, we monitored changes in renal interstitial fluid (RIF) prostaglandin E2 (PGE2) and cyclic guanosine 3', 5'-monophosphate (cGMP) in response to dietary sodium (Na) depletion alone, or Na depletion or normal Na diet combined with the AT1 receptor blocker, Losartan, the AT2 receptor blocker, PD 123319 (PD), or angiotensin II, individually or combined in conscious rats. Na depletion significantly increased PGE2 and cGMP. During Na depletion, Losartan decreased PGE2 and did not change cGMP. In contrast, PD significantly increased PGE2 and decreased cGMP. Combined administration of Losartan and PD decreased PGE2 and cGMP. During normal Na diet, RIF PGE2 and cGMP increased in response to angiotensin II. Neither Losartan nor PD, individually or combined, changed RIF PGE2 or cGMP. Combined administration of angiotensin II and Losartan or PD produced a significant decrease in response of PGE2 and cGMP to angiotensin II, respectively. These data demonstrate that activation of the reninangiotensin system during Na depletion increases renal interstitial PGE2 and cGMP. The AT1 receptor mediates renal production of PGE2. The AT2 receptor mediates cGMP. AT2 blockade potentiates angiotensin-induced PGE2 production at the AT1 receptor.     

Prostaglandins and thromboxanes in amniotic fluid during rivanol-induced abortion and labour

Abortion or delivery were induced by extra-amniotic instillation of Rivanol during the second trimester in twelve patients and during the third trimester in two patients with fetal death and one patient with fetal acrania. Serial sampling of amniotic fluid was performed through a transabdominal catheter and the levels of free arachidonic acid (AA), prostaglandin F2 alpha (PGF2 alpha), prostaglandin E2 (PGE2), 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) and thromboxane B2 (TXB2) were determined. The levels of AA, PGF2 alpha, PGE2, 6-keto-PGF1 alpha and TXB2 in amniotic fluid increased significantly during induction with the exception of AA in fetal death which was high and remained constant during induction. Furthermore, PGF2 alpha, 6-keto-PGF1 alpha and TXB2 were all significantly correlated to AA. These observations suggested that free AA is released during Rivanol-induction of abortion and labour giving an increased synthesis of PGF2 alpha, PGE2 prostacyclin and thromboxane A2 in the fetal membranes and the decidua but not in the fetus. This increase might be relevant for the initiation and progress of abortion and labour in these patients.     

Role of nitric oxide in gonadotropin-releasing hormone-dependent prostaglandin F2 alpha synthesis by frog (Rana esculenta) interrenal gland during post-reproduction

The aim of this study was to clarify the possible involvement of nitric oxide (NO) on prostaglandin (PG) E2-9-ketoreductase activity in the gonadotropin-releasing hormone (GnRH)-dependent PGF2 alpha synthesis by the interrenal gland of the female water frog, Rana esculenta, during the post-reproduction. Interrenal glands were incubated in vitro with GnRH, NO donor (sodium nitroprusside, SNP), and inhibitors of phospholipase C (compound 48/80), inositol triphosphate (decavanadate), calmodulin (calmidazolium), NO synthase (L-NAME), and PGE2-9-ketoreductase (palmitic acid). Production of PGE2 and PGF2 alpha and NO synthase and PGE2-9-ketoreductase activities were determined. GnRH and SNP increased PGF2 alpha production and PGE2-9-ketoreductase activity, and decreased production of PGE2 and GnRH increased NO synthase activity. GnRH effects were blocked by all inhibitors, except for palmitic acid, which did not affect NO synthase activity, which is increased by GnRH. This study indicates that NO may be involved in regulation of the R. esculenta post-reproduction through stimulation of PGE2-9-ketoreductase activity in GnRH-dependent PGF2 alpha synthesis by the frog interrenal gland.     

Inhibition of platelet function by A02131-1, a novel inhibitor of cGMP-specific phosphodiesterase, in vitro and in vivo

The effect of A02131-1 [3-(5'-hydroxymethyl-2'-furyl)-1-benzyl thieno (3,2-c)pyrazole], a cGMP-specific phosphodiesterase (PDE) inhibitor, on platelet function was investigated. The compound was found to inhibit the aggregation of and adenosine triphosphate (ATP) release from human platelet-rich plasma and washed platelets that were induced by aggregation inducing drugs such as arachidonic acid (AA), collagen, U46619, platelet-activating factor (PAF), adenosine diphosphate (ADP) and A23187, and the inhibitory effect was concentration-dependent. A02131-1 also disaggregated the performed platelet aggregates induced by these inducers. Thromboxane B2 (TXB2) formations caused by collagen, PAF, ADP, and A23187 were inhibited by A02131-1 at concentrations that did not affect the AA-induced formation of TXB2 and prostaglandin D2 (PGD2). A02131-1 suppressed both the generation of inositol 1,4,5-triphosphate (IP3) and the increase of intracellular Ca2+ concentration stimulated by these aggregation inducers. A02131-1 was shown to increase the cAMP and cGMP levels in platelets and the extent was found to be dependent on concentration as well as time. A02131-1 increased the cAMP level much more slowly than the cGMP level. Activities of adenylate cyclase, guanylate cyclase, and PDEs (type I and III) were not altered by A02131-1. However, the activity of cGMP-specific PDE (type V) was inhibited by A02131-1. The antiplatelet aggregation activity and the effect on raising cAMP level of A02131-1 were both potentiated by prostaglandin E1 (PGE1). In the mouse tail bleeding test, A02131-1 was clearly shown to be more effective than dipyridamole in prolonging the tail bleeding time of conscious mice. These data indicate that A02131-1 is a cGMP-specific PDE (type V) inhibitor in human platelets.     

Mode of action of prostaglandin F2 alpha in human luteinized granulosa cells: role of protein kinase C

It is well documented that prostaglandin F2 alpha (PGF2 alpha) inhibits progesterone production in luteal cells, but its mode of action is uncertain. It has recently been suggested that PGF2 alpha acts by activating the calcium and phospholipid-dependent protein kinase, protein kinase C (PKC). This hypothesis has been tested by comparing the site and mode of action of PGF2 alpha, a PGF2 alpha analogue (cloprostenol) and the PKC activator phorbol myristate acetate (4 beta PMA) in human granulosa-lutein cells. PGF2 alpha and cloprostenol exerted similar concentration-dependent inhibitory actions on gonadotrophin-stimulated cyclic AMP (cAMP) accumulation and progesterone production by human granulosa-lutein cells. The similarity in the actions of PGF2 alpha and cloprostenol in human granulosa-lutein cells suggests that they can be used interchangeably to study the role of PGF2 alpha in the regulation of steroidogenesis in the human ovary. Gonadotrophin-stimulated cAMP accumulation and progesterone production was also concentration-dependently inhibited by 4 beta PMA. In addition, cloprostenol and 4 beta PMA also inhibited dibutyryl cAMP-stimulated progesterone production, suggesting that these compounds inhibit LH action at sites before and after the generation of cAMP. The pre-cAMP site of action can be localised to the stimulatory G-protein (Gs) as both compounds inhibited cholera toxin-stimulated cAMP accumulation without affecting forskolin-stimulated cAMP accumulation. The post cAMP site of action can be localised to actions on cholesterol side chain cleavage enzyme, as both cloprostenol and 4 beta PMA inhibited 22R hydroxycholesterol-supported progesterone production without affecting pregnenolone-supported progesterone production. The finding that cloprostenol and 4 beta PMA interact with the steroidogenic cascade in a similar manner is indicative of a shared common mediator of their actions in human granulosa-lutein cells, i.e. PKC. The inhibitory actions of PGF2 alpha and 4 beta PMA on hLH-stimulated progesterone production were abolished in the presence of the PKC inhibitor, staurosporine. In addition, in PKC-depleted cells (achieved by exposure to 4 beta PMA for 20 h) the inhibitory actions of PGF2 alpha and 4 beta PMA were abolished. These results support the hypothesis that the inhibitory actions of PGF2 alpha are mediated by PKC in human granulosa-lutein cells.     

Penetration of natural prostaglandins and their ester prodrugs and analogs across human ocular tissues in vitro

The objective of this study was to assess the corneal and scleral permeabilities of natural prostaglandins as well as their prodrugs and analogs through human cornea and sclera in vitro. The "apparent permeability coefficients" (Papp) of natural prostaglandins (PGF2alpha, PGD2 and PGE2), ester prodrugs of PGF2alpha (1-isopropyl PGF2alpha, 11-pivaloyl PGF2alpha and 11,15-dipivaloyl PGF2alpha) and four analogs (16-m-chlorophenoxy tetranor PGF2alpha, 17-phenyl trinor PGF2alpha, 17-phenyl trinor PGE2 and AH 13205) were measured using modified Ussing perfusion chambers and quantitative high performance liquid chromatography. Our results indicate that the corneal penetration of natural prostaglandins (PGs) is poor (the Papp values ranged from 1.65 x 10(-6) to 2.38 x 10(-6) cm/sec), while the PGF2alpha prodrugs showed higher corneal penetration than PGF2alpha. The 11-pivaloyl ester of PGF2alpha penetrated the cornea faster than both 1-isopropyl ester and the lipophilic 11,15-dipivaloyl ester. The PG analogs also showed poor corneal penetration (Papp values ranged from 0.696 x 10(-6) to 1.49 x 10(-6) cm/sec) except for AH 13205. All compounds tested showed good scleral penetration (Papp values ranged from 6.90 x 10(-6) to 17.1 x 10(-6) cm/sec) except PGF2alpha 11,15-dipivaloyl (Papp = 1.22 x 10(-6) cm/sec). The penetration profiles correlated well with tissue uptake ratios (ratio of final tissue concentration to initial dose) for all compounds except 11,15-dipivalate PGF2alpha. All ester prodrugs (but not the PGs and analogs) underwent corneal first-pass metabolism. The study results demonstrate that transcleral absorption may play a significant role in the ocular absorption of these compounds.     

Hypothalamic areas involved in prostaglandin (PG)-induced gonadotropin release. I: effects of PGE2 and PGF2alpha implants on luteinizing hormone release

Ovariectomized rats had a cannula inserted unilaterally within various hypothalamic areas. Several days later they were primed with a sc dose of 10 microng of estradiol benzoate (Eb). Two days after priming they were etherized and an initial blood sample was drawn from the external jugular vein. An inner cannula containing PGE2 or PGF2alpha at its tip was inserted into the previously implanted outer cannula. Blood samples were drawn at 20, 40, 60, and 120 min following the implantation. PGE2 induced a 4-5-fold increase in plasma LH 40 to 60 min following its implantation in the arcuate nucleus-median eminence region (ARH-ME). Levels were already significantly elevated at 20 min. When PGE2 was placed slightly more dorsally, close to the ventromedial nucleus (VMH), LH titers rose to comparable levels but only after a delay of 120 min. PGE2 implanted in the caudal portion of the ARH-ME or dorsally in the VMH-dorsomedial nuclei, barely increased plasma LH, whereas its placement in the anterior portion of the ARH-ME clearly elevated LH titers. PGE2 implants located more than 1 mm lateral from the midline or outside the hypothalamus were ineffective. When PGE2 was placed in the preoptic area (POA) or anterior ventral portion of the anterior hypothalamic area (AHA), plasma LH levels rose strikingly, the first significant increase being observed at 20 min. PGE2 implants located in the vicinity of the paraventricular nucleus-dorsal portion of AHA were much less effective. PGF2alpha implanted in the ARH-ME or POA induced a small increase in plasma LH and the implantation of empty cannulae in the same areas was ineffective. Intrapituitary implants of PGE2 failed to alter plasma LH significantly. The results indicate that PGE2 acts at the ARH-ME region to induce LH release and that an even more effective site of action seems to be located in the POA-AHA. Since these are areas which contain LHRH, the results support the view that PGs can activated LHRH-secreting neurons in these regions.     

Prostaglandin synthesis by cumulus-oocyte complexes: effects on in vitro fertilization in mice

Cumulus-oocyte complexes, obtained from superovulated Balb/C virgin female mice, released to the incubation media significant amounts of PGE1, PGE2 and PGF2 alpha, as estimated by bioassay. Fertilization rates in vitro decreased sharply when cumulus-oocyte complexes were treated with indomethacin (10(-6) M) and then inseminated with 5000 sperm per oocyte. In order to explore if the reduced prostaglandin (PG) concentration was responsible for diminished fertilization rates, PGE1, PGE2 and PGF2 alpha (10(-9) M) were added to the fertilization media of treated oocytes. PGE1 and PGE2 but not PGF2 alpha returned fertilization rates to control levels. Besides, PGE1 (10(-9) M) enhanced fertilization rates with reduced sperm numbers (1000 sperm per oocyte) of untreated cumulus-oocyte complexes. In conclusion, PG synthesis and release of mouse cumulus-oocyte complexes affects fertilization in vitro, and it is suggested that PGs of the E series modulate sperm function at the moment of fertilization.     

Prediction and prevention of malaria epidemics in the valley of the Senegal River

The metabolism of PGF2alpha in human and other species results initially in the formation of 15-keto-dihydro-PGF2alpha and later to several beta-oxidized metabolites, which are species-specific. Since the discovery of cyclooxygenase-2 (COX-2), the importance of measuring various arachidonic acid metabolites during inflammatory conditions is on focus. This study presents the development and validation of a new radioimmunoassay of 15-keto-dihydro-PGF2alpha as an index of lipid peroxidation via cyclooxygenase (COX-1 and COX-2) pathway. Furthermore, its application in endotoxin-induced acute inflammation in pigs is presented. An antibody was raised in rabbits by immunization with 15-keto-dihydro-PGF2alpha coupled to BSA at the carboxylic acid by 1,1'-carbonyldiimidazole method. The cross-reactivity of the antibody with PGF2alpha, 15-keto-PGF2alpha, PGE2, 15-keto-13,14-dihydro-PGE2, 8-iso-15-keto-13,14-dihydro-PGF2alpha, 11beta-PGF2alpha, 9beta-PGF2alpha, TXB2 and 8-iso-PGF3alpha was 0.02, 0.43, < 0.001, 0.5, 1.7, < 0.001, < 0.001, < 0.001, 0.01%, respectively. The intra-assay precision was 12.2% (CV) at the level of 64 pg/0.1 ml and 14.0% with 512 pg/0.1 ml in the human plasma. Similarly, intra-assay accuracy was 108.6% and 103.3% for the low and the high standards, respectively. The detection limit was about 45 pmol/L. 15-keto-dihydro-PGF2alpha levels in plasma from normal human volunteers were evaluated and found to correlate with the obtained values by GC-MS methods from other studies. The levels of 15-keto-dihydro-PGF2alpha in the plasma increased several-fold after endotoxin infusion (10 microg/kg/h over 6 h) to the pigs. Thus, this 1 5-keto-dihydro-PGF2alpha radioimmunoassay method is relevant to apply in inflammatory injury, and other physiological and pathophysiological studies, as an index of in vivo enzymatic lipid peroxidation.     

Dexamethasone inhibits the pyrogenic activity of prostaglandin F2 alpha, but not prostaglandin E2

The effect of dexamethasone on prostaglandin (PG) E2- and PGF2 alpha-induced fever was studied in rats. Intracerebroventricular injection of PGE2 and PGF2 alpha (500 ng) induced increases in body temperature (maximal temperature rises of 0.97 +/- 0.13 degrees C and 0.78 +/- 0.18 degrees C, respectively, vs. vehicle 0.12 +/- 0.09 degrees C) of unrestrained rats maintained within the thermoneutral zone. PGE2-induced fever peaked earlier and the defervescence was faster when compared to the response induced by PGF2 alpha. Subcutaneous pre-administration of dexamethasone (0.5 mg/kg) did not affect PGE2-induced fever (maximal temperature rise of 1.00 +/- 0.08 degrees C), but completely prevented the pyrogenic activity of PGF2 alpha (maximal temperature rise of 0.16 +/- 0.16 degrees C). Neither PGE2- nor PGF2 alpha-induced fever was significantly altered (maximal temperature rises of 0.90 +/- 0.11 degrees C and 0.64 +/- 0.14 degrees C, respectively) by intraperitoneal administration of indomethacin (2 mg/kg). These results demonstrate for the first time that glucocorticoids, in addition to inhibiting endotoxin- and cytokine-induced fever, can also modulate the pyrogenic activity of some prostaglandins, possibly via suppression of the synthesis of corticotropin-releasing factor, indicating that multiple mechanisms may be involved in the antipyretic activity of these steroids.