Prostaglandins最新文献

Biliary organic anion excretion is mediated by an ATP-dependent primary active transporter, so-called canalicular multispecific organic anion transporter (cMOAT). On the other hand, a multiplicity of canalicular organic anion transport has been suggested. Therefore, to examine the substrate specificity of cMOAT using inhibition of excretion of [³H] LTC₄-derived radioactive products in the bile as a marker, we examined the effects of various organic anions and bile acid conjugates on the biliary excretion of LTC₄ in rats. Biliary excretion of the metabolites of [³H] LTC₄, which was injected via the femoral vein, was markedly inhibited by sulfobromophthalein-glutathione, taurolithocholate-3-sulfate, and ursodeoxycholate-3-O-glucuronide. In contrast, dibromosulfophthalein and cefpiramide slightly inhibited, and pravastatin, taurocholate, and 3,7-sul-UDC did not affect biliary LTC₄ excretion. Furthermore, vinblastine and phenothiazine, a P-glycoprotein substrate and inducer, did not affect biliary LTC₄ excretion. Among various organic anions and bile acid conjugates, LTC₄, sulfobromophthalein-glutathione, taurolithocholate-3-sulfate, and ursodeoxycholate-3-O-glucuronide may be good substrates for cMOAT.

The effects of nonsteroidal anti-inflammatory drugs (NSAIDs), mofezolac, indomethacin, sodium diclofenac, and zaltoprofen, on the production of interleukin-1 receptor antagonist (IL-1ra) were examined in cultured human peripheral blood mononuclear cells (PBMC). Among the NSAIDs tested, mofezolac and sodium diclofenac were found to stimulate the mRNA expression for IL-1ra without affecting the mRNA expression for IL-1β. These two drugs also stimulated the secretion of IL-1ra by PBMC in the absence of bacterial lipopolysaccharide (LPS), however, the stimulatory effect of sodium diclofenac diminished in the presence of LPS. Mofezolac suppressed the mRNA expression for IL-1β in PBMC stimulated with exogenous IL-1β, indicating the secreted IL-1ra in the presence of mofezolac to be biologically active. Since IL-1ra suppresses the function of IL-1, a pro-inflammatory cytokine, the stimulatory effect of such NSAIDs as mofezolac on IL-1ra production could also be one of the mechanisms involved in its anti-inflammatory and antinociceptive actions.

Purpose: To investigate the combined effects of interleukin-2 (IL-2) with either prostaglandin E₂ (PGE₂) or indomethacin (IM) on the proliferation and cytolysis of bladder tumor cells by lymphokine-activated killer (LAK) cells in patients with bladder cancer.

Methods: LAK cell proliferation was assayed in the presence of various concentrations of either PGE₂ or IM by cell counting. Bladder cancer cell lines BIU-87, EJ and bladder tumor cells (BTC) from the patients were cultured as target cells, and the cytotoxicity of LAK cells was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. In addition, PGE₂ in samples of conditioned medium from bladder cancer cells or peripheral blood mononuclear cells (PBMC) as well as plasma from 21 patients with bladder cancer and 20 healthy donors were determined by radioimmunoassay (RIA).

Results: The proliferation of LAK cells induced by IL-2 was inhibited by PGE₂ (0.05 to 5 ng/mL) in concentration-dependent manner. The enhanced growth of LAK cells was observed at certain concentrations of IM (100–400 ng/mL) from 48 to 96 h. Pretreatment of LAK cells with IM (200 ng/mL) significantly enhanced cytotoxicity against BIU-87, EJ cells, or BTC. More PGE₂ was present in conditioned medium from BIU-87 cells than in the conditioned medium from PBMC.

Conclusions: These studies indicate that LAK cell proliferation induced by IL-2 in patients with bladder cancer is inhibited by PGE₂ produced by PBMC and bladder cancer cells. This inhibition can be overcome by IM, which may be of use in immunotherapy of bladder cancer.

Little is known about the epoxygenase pathway of the arachidonic acid cascade in uterine tissues. In this paper, we describe the formation of epoxyeicosatrienoic acids (EETs) and dihydroxyeicosatrienoic acids (DHETs) in human term placenta after uncomplicated pregnancies. Metabolism of [³H]-arachidonic acid was analyzed in short term tissue cultures of placenta by reverse phase HPLC. Major metabolites coeluted with authentic EETs and DHETs. The formation of EETs was inhibited by carbon monoxide. In non-radioactive incubations with biopsies from seven different placentas, sufficient material for GC/MS analysis was obtained. The combined media were purified by solid phase extraction and reverse phase HPLC. The fraction coeluting with DHETs was derivatized with pentafluorobenzylbromide (PFB) and bis-(trimethylsilyl)-trifluoroacetylacetamide (BSTFA) and analyzed by GC/NICI/MS/MS. 11,12-DHET and 14,15-DHET were identified by their mass spectra displaying specific fragments at m/z 149 and m/z 189, respectively. Our results suggest that the epoxygenase pathway is active in human term placenta.

Prostaglandin E₂ (PGE₂) is a potent local mediator of cell growth and differentiation in various tissues. The receptors for PGE₂ have been classified into four pharmacological subtypes, EP1, EP2, EP3, and EP4, based on the responses to selective agonists and antagonists. We have cloned a functional cDNA for the rat EP2 receptor subtype from a rat lung cDNA library. The rat EP2 receptor cDNA encodes 357 amino acid residues having high homology with the human and mouse EP2 receptors and containing seven putative transmembrane domains. In COS-7 cells transfected with rat EP2 cDNA, specific [³H]PGE₂ binding was found with a dissociation constant of 14.9 nM, and this binding was inhibited by unlabeled PGE₂ and PGF_2α. PGE₂ and butaprost, an EP2 selective agonist, were effective in increasing the cAMP level in the COS-7 cell transfectants. Northern blot and RT-PCR analysis showed widespread distribution of the EP2 receptor in various tissues. Higher EP2 expression was found in fetal long bones and calvariae than in adult by RT-PCR and in situ hybridization, suggesting a role for this receptor in rapidly growing skeletal tissue.

Prostaglandin (PG) release is characteristic of most inflammatory diseases. The committed step in the formation of free arachidonic acid into PG products is catalyzed by cyclooxygenase (COX, prostaglandin H₂ synthase, PGHS), which exists as two genetically distinct isoforms. COX-1 is constitutively expressed and produces PGs and thromboxane A₂ during normal physiologic activities, while COX-2 is an inducible enzyme stimulated by growth factors, lipopolysaccharide, and cytokines during inflammation or cell injury. Proinflammatory cytokines such as tumor necrosis factor-α (TNF-α) released into the amniotic fluid in the setting of infection have been proposed to signal amnion and decidual cells to produce PGs that may culminate in preterm labor. However, since the molecular control of this phenomenon has not been established, this study used amnion-derived WISH cells to determine if TNF-α promoted the formation of PGs through COX-2 activity. Treatment of WISH cells with TNF-α (0.1 ng/mL–100 ng/mL) caused a dose-dependent increase in COX-2 expression and the subsequent biosynthesis of PGE₂ that persisted for at least 48 hrs. In contrast, COX-1 mRNA and protein levels were unaltered by TNF-α treatment as determined by RT-PCR and immunoblot analysis, respectively. TNF-α-stimulated COX-2 expression and the subsequent formation of PGE₂ were inhibited by dexamethasone (0.1 μM). In addition, indomethacin (1 μM) and the novel COX-2-selective inhibitor, NS-398 (IC₅₀ ∼ 1.1 × 10⁻⁹ M), attenuated TNF-α-elicited PGE₂ production. Results presented here demonstrate that TNF-α elicits prolonged and regulatable induction of COX-2 in WISH cells, while COX-1 is constitutively expressed and unchanged in response to TNF-α stimulation.

Lipids in the synovial fluid of patients with active rheumatoid arthritis are elevated compared to normal synovial fluid and that of other inflammatory arthropathies. Various assumptions about the role of these lipids have been made. This study offers evidence that these lipids may contribute to the synovitis in rheumatoid arthritis through participation in the arachidonic pathway within the joint space. Phospholipase A₂ activity, phospholipids, prostaglandin E₂, and leukotriene B₄ have been correlated in the synovial fluid and plasma of untreated rheumatoid patients and compared with that of patients with osteoarthritis.

The kinetic profiles of leukotriene B₄ (LTB₄) and E₄ (LTE₄) after intravenous administration (30 nmol/kg) of the inflammatory peptide N-formyl-l-methionyl-l-leucyl-l-phenylalanine (FMLP) were evaluated in male rabbits. LTB₄ and LTE₄ reached the maximal concentration of 84.2 ± 60.0 and 162.2 ± 51.4 nmol/L (mean ± s.d.), at 2 and 5 min, respectively. The first elimination phase for LTB₄ and LTE₄, after FMLP administration, showed an apparent half-life of 24.6 ± 6.7 and 36.9 ± 13.0 min, respectively. The area under the blood concentration-time curve (AUC, nmol min/L) of LTB₄ and LTE₄ was 2178 ± 1591 and 7627 ± 3052, respectively. LTE₄ and N-ac-LTE₄ were the major components excreted in the urine, mostly in the first time interval (0–12 h) of urinary collection after FMLP treatment; 11-trans-LTE₄ was recovered in the second interval (12–24 h). Two other more polar compounds, potential metabolites, were recovered in the first interval of urine collection. Knowledge of the kinetic characteristics of endogenously produced leukotrienes may be useful in understanding the role of these eicosanoids in inflammatory and thrombotic disease, as well as in evaluating the efficacy of drugs designed to modulate their production and effect.

Prostaglandins (PGs) were first described in the brain by Samuelsson over 30 years ago (Samuelsson, 1964). Since then a large number of studies have shown that PGs are formed in regions of the brain and spinal cord in response to a variety of stimuli. The recent identification of two forms of cyclooxygenase (COX; Kujubu et al., 1991; Xie et al., 1991; Smith and DeWitt, 1996), both of which are expressed in the brain, along with superior tools for mapping COX distribution, has spurred a resurgence of interest in the role of PGs in the central nervous system (CNS). In this review we will describe new data in this area, focusing on the distribution and potential role of the COX isoforms in brain function and disease.

The purpose of the present work was to study the prostaglandin excretion in young nonpregnant ovulatory women during the menstrual cycle on the one hand and in postmenopausal women on the other hand and to investigate the influence of female sex hormones (estradiol, progesterone) on urinary prostanoid excretion. Urinary excretion rates of prostaglandin E₂ (PGE₂), 6-keto-PGF_1α, thromboxane B₂ (TxB₂) and their metabolites PGE-M (11α-hydroxy-9,15-dioxo-2,3,4,5,20-pentanor-19-carboxyprostanoic acid), 2,3-dinor-6-keto-PGF_1α, 2,3-dinor-TxB₂ and 11-dehydro-TxB₂ were determined by gas chromatography-triple stage quadrupole mass spectrometry (GC/MS/MS) in 41 young nonpregnant women during the follicular phase and during the luteal phase and in 23 postmenopausal women. Excretion rates of all urinary prostanoids were not significantly different in the follicular phase when compared with the luteal phase. In contrast to the young ovulatory women, PGE₂ and TxB₂ were significantly higher in postmenopausal women. Concerning the other prostaglandins significant differences between these groups of women did not exist. Although serum levels of estradiol and progesterone were different in young and postmenopausal women, sex hormones have not been shown to correlate with prostaglandins. Our data do not suggest sex hormones to be responsible for the difference in the prostaglandin excretion in women of reproductive age and in women in the menopause. Further systematic investigations into age dependency of prostaglandin excretion in women are necessary.