Lonicera japonica THUNB. Extract Inhibits Lipopolysaccharide-Stimulated Inflammatory Responses by Suppressing NF-κB Signaling in BV-2 Microglial Cells.

In the current study, we evaluated the anti-inflammatory effects of Lonicera japonica THUNB. (LJ) and its underlying molecular mechanism in lipopolysaccharide (LPS)-stimulated BV-2 microglial cells. Our results indicated that LJ significantly inhibits LPS-stimulated production of nitric oxide (NO) and prostaglandin E2 (PGE2). In addition, LJ inhibited inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) at both the protein and mRNA levels. In LPS-stimulated BV-2 microglial cells, LJ inhibited proinflammatory cytokines and chemokines, tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), monocyte chemoattractant protein-1 (MCP-1), matrix metalloproteinase-9 (MMP-9) enzymatic activities, and/or mRNA expression, as well as reactive oxygen species (ROS) production. LJ significantly suppressed activation of nuclear factor-κB (NF-κB) and its translocation from the cytosol to the nucleus and suppressed the DNA-binding activity of NF-κB. Furthermore, LJ significantly inhibited phosphorylation of c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase 1/2 (ERK 1/2), p38 mitogen-activated protein kinases (MAPKs), phosphatidylinositol 3-kinases (PI3K)/Akt, and Janus kinase 1 (JAK1)/signal transducer and activator of transcription (STAT)1/3. Collectively, our findings indicated that the antineuroinflammatory properties of LJ in LPS-induced BV-2 microglial cells is due to downregulation of proinflammatory cytokines and chemokines downstream of inhibition of NF-κB activation.

Culture of mouse peritoneal macrophages with mouse serum induces lipid bodies that associate with the parasitophorous vacuole and decrease their microbicidal capacity against Toxoplasma gondii.

Lipid bodies [lipid droplets (LBs)] are lipid-rich organelles involved in lipid metabolism, signalling and inflammation. Recent findings suggest a role for LBs in host response to infection; however, the potential functions of this organelle in Toxoplasma gondii infection and how it alters macrophage microbicidal capacity during infection are not well understood. Here, we investigated the role of host LBs in T. gondii infection in mouse peritoneal macrophages in vitro. Macrophages cultured with mouse serum (MS) had higher numbers of LBs than those cultured in foetal bovine serum and can function as a model to study the role of LBs during intracellular pathogen infection. LBs were found in association with the parasitophorous vacuole, suggesting that T. gondii may benefit from this lipid source. Moreover, increased numbers of macrophage LBs correlated with high prostaglandin E2 (PGE2) production and decreased nitric oxide (NO) synthesis. Accordingly, LB-enriched macrophages cultured with MS were less efficient at controlling T. gondii growth. Treatment of macrophages cultured with MS with indomethacin, an inhibitor of PGE2 production, increased the microbicidal capacity against T. gondii. Collectively, these results suggest that culture with MS caused a decrease in microbicidal activity of macrophages against T. gondii by increasing PGE2 while lowering NO production.

Culture of mouse peritoneal macrophages with mouse serum induces lipid bodies that associate with the parasitophorous vacuole and decrease their microbicidal capacity against Toxoplasma gondii

Lipid bodies [lipid droplets (LBs)] are lipid-rich organelles involved in lipid metabolism, signalling and inflammation. Recent findings suggest a role for LBs in host response to infection; however, the potential functions of this organelle in Toxoplasma gondii infection and how it alters macrophage microbicidal capacity during infection are not well understood. Here, we investigated the role of host LBs in T. gondii infection in mouse peritoneal macrophages in vitro. Macrophages cultured with mouse serum (MS) had higher numbers of LBs than those cultured in foetal bovine serum and can function as a model to study the role of LBs during intracellular pathogen infection. LBs were found in association with the parasitophorous vacuole, suggesting that T. gondii may benefit from this lipid source. Moreover, increased numbers of macrophage LBs correlated with high prostaglandin E2 (PGE2) production and decreased nitric oxide (NO) synthesis. Accordingly, LB-enriched macrophages cultured with MS were less efficient at controlling T. gondii growth. Treatment of macrophages cultured with MS with indomethacin, an inhibitor of PGE2 production, increased the microbicidal capacity against T. gondii. Collectively, these results suggest that culture with MS caused a decrease in microbicidal activity of macrophages against T. gondii by increasing PGE2 while lowering NO production.

Ultraviolet radiation-induced inflammation activates ß-catenin signaling in mouse skin and skin tumors.

UVB-induced inflammation, in particular the overexpression of cyclooxygenase-2 (COX-2) and prostaglandin (PG) E2, has been implicated in photocarcinogenesis. UVB-induced COX-2 has been associated with ß-catenin signaling in keratinocytes. However, a definitive role for COX-2 in the activation of ß-catenin signaling as well as its role in UVB-induced skin tumors has not been established. We report that exposure of the skin to UVB resulted in a time- and dose-dependent activation of ß-catenin in C3H/HeN mice. This response was COX-2-dependent as UVB-exposed COX-2-deficient mice exhibited significantly lower levels of UVB-induced activation of ß-catenin. Moreover, treatment of mice with indomethacin, a COX-2 inhibitor, and an EP2 antagonist inhibited UVB-induced ß-catenin signaling. Exposure of SKH-1 hairless mice to UVB radiation (180 mJ/cm2) 3 times a week for 24 weeks resulted in activation of ß-catenin signaling in UVB-irradiated skin as well as UVB-induced skin tumors. Concomitantly, the levels of CK1α and GSK-3ß, which are responsible for ß-catenin signaling, were reduced while the levels of c-Myc and cyclin D1, which are downstream targets of ß-catenin, were increased. To further verify the role of UVB-induced inflammation in activation of ß-catenin signaling, a high-fat-diet model was used. Administration of high-fat diet exacerbated UVB-induced inflammation. Administration of the high-fat diet enhanced ß-catenin signaling and the levels of its downstream targets (c-Myc, cyclin D1, cyclin D2, MMP-2 and MMP-9) in UVB-exposed skin and skin tumors in SKH-1 mice. These data suggest that UV-induced COX-2/PGE2 stimulates ß-catenin signaling, and that ß-catenin activation may contribute to skin carcinogenesis.

Decidual stromal cells promote regulatory T cells and suppress alloreactivity in a cell contact-dependent manner.

Acute graft-versus-host disease (GvHD) is a severe adverse event after stem cell transplantation. Bone marrow-derived mesenchymal stromal cells (BM-MSCs) have been used to treat GvHD, but decidual stromal cells (DSCs) isolated from term fetal membrane have advantages compared with BM-MSCs, including increased allosuppression, unlimited supply, and high expression of integrins. We introduced the use of DSCs in patients with steroid refractory aGvHD. In this study, we investigated factors of importance in the reduction of alloreactivity by DSCs. We found that DSCs need to have cell-cell contact in order to mediate suppression in mixed lymphocyte reactions (MLRs). This contact dependency is consistent with an increased frequency of CD4(+)CD25(high)FOXP3(+) regulatory T cells (Tregs) and an augmented intensity of CD25 expression in CD4(+) T cells. Blocking of the activity of indoleamine-2,3-dioxygenase (IDO), prostaglandin E2, PD-L1, and IFN-γ impaired the antiproliferative ability of the DSCs in MLRs. Neutralization of IDO also reduced the frequency of Tregs. In contrast to BM-MSCs, pretreatment of DSCs with high concentrations of IFN-γ (100 U/mL) reduced their ability to suppress alloreactivity, but stimulation of DSCs with MLR supernatants containing low levels of IFN-γ had no effect on the suppressive capacity in MLR. To conclude, DSCs differ in several aspects from MSCs and need to be close to alloreactive lymphocytes to mediate a suppressive effect and increase the frequency of Tregs. Thus, DSCs may not only use paracrine factors for systemic immunosuppression, but also more specifically target T cells locally in affected tissues.

Cyclooxygenase-2 up-regulates vascular endothelial growth factor via a protein kinase C pathway in non-small cell lung cancer.

BACKGROUND: Vascular endothelial growth factor (VEGF) expression is up-regulated via a cyclooxygenase-2 (COX-2)-dependent mechanism in non-small cell lung cancer (NSCLC), but the specific signaling pathway involved is unclear. Our aim was to investigate the signaling pathway that links COX-2 with VEGF up-regulation in NSCLC. MATERIAL AND METHODS: COX-2 expression in NSCLC samples was detected immunohistochemically, and its association with VEGF, microvessel density (MVD), and other clinicopathological characteristics was determined. The effect of COX-2 treatment on the proliferation of NSCLC cells (A549, H460 and A431 cell lines) was assessed using the tetrazolium-based MTT method, and VEGF expression in tumor cells was evaluated by flow cytometry. COX-2-induced VEGF expression in tumor cells was monitored after treatment with inhibitors of protein kinase C (PKC), PKA, prostaglandin E2 (PGE2), and an activator of PKC. RESULTS: COX-2 over-expression correlated with MVD (P = 0.036) and VEGF expression (P = 0.001) in NSCLC samples, and multivariate analysis demonstrated an association of VEGF with COX-2 expression (P = 0.001). Exogenously applied COX-2 stimulated the growth of NSCLCs, exhibiting EC50 values of 8.95 × 10(-3), 11.20 × 10(-3), and 11.20 × 10(-3) µM in A549, H460, and A431 cells, respectively; COX-2 treatment also enhanced tumor-associated VEGF expression with similar potency. Inhibitors of PKC and PGE2 attenuated COX-2-induced VEGF expression in NLCSCs, whereas a PKC activator exerted a potentiating effect. CONCLUSION: COX-2 may contribute to VEGF expression in NSCLC. PKC and downstream signaling through prostaglandin may be involved in these COX-2 actions.

Effect of eicosapentaenoic acid on E-type prostaglandin synthesis and EP4 receptor signaling in human colorectal cancer cells.

The omega-3 polyunsaturated fatty acid eicosapentaenoic acid (EPA), in the free fatty acid (FFA) form, has been demonstrated to reduce adenoma number and size in patients with familial adenomatous polyposis. However, the mechanistic basis of the antineoplastic activity of EPA in the colorectum remains unclear. We tested the hypothesis that EPA-FFA negatively modulates synthesis of and signaling by prostaglandin (PG) E(2) in human colorectal cancer (CRC) cells. EPA-FFA induced apoptosis of cyclooxygenase (COX)-2-positive human HCA-7 CRC cells in vitro. EPA-FFA in cell culture medium was incorporated rapidly into phospholipid membranes of HCA-7 human CRC cells and acted as a substrate for COX-2, leading to reduced synthesis of PGE(2) and generation of PGE(3). Alone, PGE(3) bound and activated the PGE(2) EP4 receptor but with reduced affinity and efficacy compared with its "natural" ligand PGE(2). However, in the presence of PGE(2), PGE(3) acted as an antagonist of EP4 receptor-dependent 3',5' cyclic adenosine monophosphate induction in naturally EP4 receptor-positive LoVo human CRC cells and of resistance to apoptosis in HT-29-EP4 human CRC cells overexpressing the EP4 receptor. We conclude that EPA-FFA drives a COX-2-dependent "PGE(2)-to-PGE(3) switch" in human CRC cells and that PGE(3) acts as a partial agonist at the PGE(2) EP4 receptor.

Furo[3',2':3,4]naphtho[1,2-d]imidazole derivatives as potential inhibitors of inflammatory factors in sepsis.

Synthesis and anti-inflammatory effects of certain furo[3',2':3,4]naphtho[1,2-d]imidazole derivatives 12-18 were studied. These compounds were synthesized from naphtho[1,2-b]furan-4,5-dione (10) which in turn was prepared from the known 2-hydroxy-1,4-naphthoquinone (7) in a one pot reaction. Furo[3',2':3,4]naphtho[1,2-d]imidazole (12) was inactive (IC(50) value of >30 microM) while its 5-phenyl derivative 13, with an IC(50) value of 16.3 and 11.4 microM against lysozyme and beta-glucuronidase release, respectively, was comparable to the positive trifluoperazine. The same potency was observed for 5-furan derivative 16 with an IC(50) value of 19.5 and 11.3 microM against lysozyme and beta-glucuronidase release, respectively. An electron-withdrawing NO(2) substituted on 5-phenyl or 5-furanyl group led to the devoid of activity as in the cases of 14 and 17. Among them, compound 15 exhibited significant inhibitory effects, with an IC(50) value of 7.4 and 5.0 microM against lysozyme and beta-glucuronidase release, respectively. For the LPS-induced NO production, the phenyl derivatives 12-15 were inactive while the nitrofuran counterparts 17 and 18 suppress LPS-induced NO production significantly, with an IC(50) value of 1.5 and 1.3 microM, respectively, which are more active than that of the positive 1400 W. Compounds 16-18 were capable of inhibiting LPS-induced iNOS protein expression at a dose-dependent manner in which compound 18, with an IC(50) of 0.52 microM in the inhibition of iNOS expression, is approximately fivefold more potent than that of the positive 1400 W. In the CLP rat animal model, compound 18 was found to be more active than the positive hydrocortisone in the inhibition of the iNOS mRNA expression in rat lung tissue. The sepsis-induced PGE2 production in rat serum decreased 150% by the pretreatment of 18 in a dose of 10 mg/kg.

Reciprocal interactions between human mesenchymal stem cells and gammadelta T cells or invariant natural killer T cells.

The immunomodulatory activities of human mesenchymal stem cells (MSCs) provide a rational basis for their application in the treatment of immune-mediated diseases, such as graft versus host disease and multiple sclerosis. The effects of MSCs on invariant natural killer T (iNKT) and gammadelta T cells, both involved in the pathogenesis of autoimmune diseases, are unknown. Here, we investigated the effects of MSCs on in vitro expansion of these unconventional T-cell populations. MSCs inhibited iNKT (Valpha24(+)Vbeta11(+)) and gammadelta T (Vdelta2(+)) cell expansion from peripheral blood mononuclear cells in both cell-to-cell contact and transwell systems. Such inhibition was partially counteracted by indomethacin, a prostaglandin E(2) inhibitor. Block of indoleamine 2,3-deoxygenase and transforming growth factor beta1 did not affect Valpha24(+)Vbeta11(+) and Vdelta2(+) cell expansion. MSCs inhibited interferon-gamma production by activated Valpha24(+)Vbeta11(+) and impaired CD3-mediated proliferation of activated Valpha24(+)Vbeta11(+) and Vdelta2(+) T cells, without affecting their cytotoxic potential. MSCs did not inhibit antigen processing/presentation by activated Vdelta2(+) T cells to CD4(+) T cells. In contrast, MSCs were lysed by activated Vdelta2(+) T cells through a T-cell receptor-dependent mechanism. These results are translationally relevant in view of the increasing interest in MSC-based therapy of autoimmune diseases.

In vivo progestin treatments inhibit nitric oxide and endothelin-1-induced bovine endometrial prostaglandin (PG) E (PGE) secretion in vitro.

Synchronization of estrus with progestins in cows has been reported to inhibit nitric oxide (NO) and endothelin-1 (ET-1)-stimulated bovine luteal PGE secretion without affecting prostaglandin F2alpha (PGF2alpha) secretion in vitro [Weems YS, Randel RD, Tatman S, Lewis A, Neuendorff DA, Weems CW. Does estrous synchronization affect corpus luteum (CL) function? Prostaglandins Other Lipid Mediat 2004;74:45-59]. Two experiments were conducted to determine the effects of NO donors, endothelin-1 (ET-1), and NO synthase (NOS) inhibitors on bovine caruncular endometrial secretion of PGE and PGF2alpha in vitro. In Experiment 1, estrus was synchronized in Brahman cows with Synchromate-B ear implants, which contained the synthetic progestin norgestamet. Days 14-15 caruncular endometrial slices were weighed, diced, and incubated in vitro with treatments. Treatments (100 ng/ml) were: Vehicle (control), l-NAME (NOS inhibitor), l-NMMA (NOS inhibitor), DETA (control), DETA-NONOate (NO donor), sodium nitroprusside (NO donor), or ET-1. In Experiment 2, estrus was synchronized in Brahman cows with either Lutalyse (PGF2alpha) or a controlled intravaginal drug releasing device (CIDR-containing progesterone) or estrus was not synchronized. Days 14-15 caruncular endometrial slices were weighed, diced, and incubated in vitro with treatments. Treatments (100 ng/ml) were: vehicle, l-NAME, l-NMMA, DETA, DETA-NONOate, sodium nitroprusside, SNAP (NO donor) or ET-1. Tissues were incubated in M-199 for 1h without treatments and with treatments for 4 and 8h in both experiments. Media were analyzed for concentrations of PGE and PGF2alpha by radioimmunoassay (RIA). Hormone data in Experiments 1 and 2 were analyzed by 2x7 and 3x2x8 factorial design for ANOVA, respectively. Concentrations of PGE and PGF2alpha in media increased (P< or =0.05) from 4 to 8 h regardless of treatment group in Experiment 1, but did not differ (P> or =0.05) among treatments. In Experiment 2, concentrations of PGE and PGF2alpha increased (P< or =0.05) with time in all treatment groups of all three synchronization regimens. DETA-NONOate, SNAP, and sodium nitroprusside (NO donors) and ET-1 increased caruncular endometrial (P< or =0.05) secretion of PGE2 in unsynchronized and Lutalyse synchronized cows, but not when estrus was synchronized with a CIDR (P> or =0.05). No treatment increased (P> or =0.05) PGF2alpha in any synchronization regimen. It is concluded that norgestamet in Synchromate-B ear implants or progesterone in a CIDR alters NO or ET-1-induced secretion of PGE by bovine caruncular endometrium and could interfere with implantation by altering the PGE:PGF2alpha ratio resulting in increased embryonic losses during early pregnancy.

Bone-targeting macromolecular therapeutics.

Musculoskeletal diseases such as osteoporosis are recognized as major public health problems worldwide. Many novel therapeutic agents have been identified for the treatment of these diseases. However, the majority of them are not specific to hard tissue, resulting significant toxicity. Bone-targeting drug delivery systems based on water-soluble polymers can specifically direct candidate drugs to bone thereby reducing side effects due to non-specific tissue interactions. Incorporation of a targeting moiety, a drug release mechanism, drug selection and optimization of the polymer carrier are all essential elements in the development of bone-targeting macromolecular therapeutics. Successful clinical application of this approach can significantly contribute to the development of treatments for many musculoskeletal diseases.

Benzo[a]pyrene regulates osteoblast proliferation through an estrogen receptor-related cyclooxygenase-2 pathway.

Polycyclic aromatic hydrocarbons (PAHs) have been known as a kind of xenoestrogen. Benzo[a]pyrene, a PAH present in tobacco smoke and tar, has been implicated in the induction of cell proliferation as well as tumors including osteosarcoma. Nevertheless, the literature about the action of benzo[a]pyrene on the bone system is rare. It has been identified that osteoblasts owned the estrogen receptors and estrogen could modulate the osteoblast proliferation. In this study, we found that benzo[a]pyrene was capable of increasing the cell proliferation in cultured rat osteoblasts, human osteosarcoma cell line (MG-63), and estrogen sensitive human cell line (MCF-7) but not in the human estrogen receptor negative cell line (MDA-MB-231). This benzo[a]pyrene-induced osteoblast proliferation could be inhibited by the estrogen receptor antagonist ICI182780 and tamoxifen, PD98059 [extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) inhibitor], and LY294002 [phosphatidylinositol 3-kinase (PI3K) inhibitor] but not alpha-naphthoflavone (aryl hydrocarbon receptor antagonist) and SB203580 (p38 MAPK inhibitor). Western blot analysis showed that benzo[a]pyrene could induce the phosphorylation of ERK1/2 and Akt (PI3K downstream effector) in osteoblasts. The proliferating cell nuclear antigen protein levels in nuclear fraction of osteoblasts were also increased by benzo[a]pyrene. Moreover, cyclooxygenase-2 (COX-2), but not COX-1, expression could be induced in osteoblasts under benzo[a]pyrene treatment. Its upregulation was associated with the induction of prostaglandin E(2) (PGE(2)). COX-2 inhibitors NS398 and aspirin are capable of inhibiting the benzo[a]pyrene-induced osteoblast proliferation. These results indicate that benzo[a]pyrene may modulate the osteoblast proliferation through activation of COX-2 protein.

Efficacy and specificity of non-steroidal anti-inflammatory drugs for the inhibition of cytokine-stimulated prostaglandin E(2) secretion by amnion-derived WISH cells.

Prostaglandin H synthase-2 (PGHS-II) specific inhibitors have been proposed as a potential treatment in the prevention of preterm birth. We examined the efficacy of PGHS inhibitors on basal and cytokine-stimulated prostaglandin (PG) production by the amnion-like WISH cell line. WISH cells were treated with interleukin (IL)-1 beta and tumour necrosis factor (TNF)-alpha in the presence or absence of indomethacin, etodolac, 5,5-dimethy-3-(3-fluorophenyl)-4-(4-methlysulphonyl) phenyl-2 (5H)-furanone (DFU) or nimesulide (1.6-1000 nM) for 16 h. PG production was then measured using radioimmunoassay. Nimesulide and DFU were the most selective non-steroidal anti-inflammatory drugs (NSAIDs) of IL-beta-stimulated PG production in these studies with an a IC(50)(basal)/IC(50)(stimulated) ratio of, respectively, 142.2 and 113.8, followed by etodolac (25.3) and indomethacin (2.2). Similar results were obtained when cells were stimulated with TNF-alpha. The results of this study suggest that PGHS-II-selective NSAIDs may be effective in the prevention of cytokine-driven amnion PG production associated with preterm labour.

alpha(2A)-adrenergic receptor stimulation potentiates calcium release in platelets by modulating cAMP levels.

alpha(2A)-Adrenergic receptor-mediated Ca(2+) signaling and integrin alpha(IIb)beta(3) exposure were investigated in human platelets under conditions where indirect, thromboxane- or ADP-mediated effects were absent. The alpha(2)-adrenergic receptor agonists, UK14304 and epinephrine (EPI), were unable to raise cytosolic levels of inositol 1,4,5-trisphosphate (InsP(3)) or Ca(2+) but potentiated the [Ca(2+)](i) rises evoked by other agonists that act through stimulation of phospholipase C (thrombin or platelet-activating factor) or stimulation of Ca(2+)-induced Ca(2+) release (CICR) in the absence of InsP(3) generation (thimerosal or thapsigargin). In addition, alpha(2)-adrenergic stimulation resulted in a 20% lowering in the cytosolic cAMP level. In platelets treated with G(salpha)-stimulating prostaglandin E(1), EPI increased the Ca(2+) signal evoked by either phospholipase C- or CICR-stimulating agonists mainly through modulation of the cAMP level. The stimulating effects of UK14304 and EPI on platelet Ca(2+) responses, and also on integrin alpha(IIb)beta(3) exposure and platelet aggregation, were abolished by pharmacological stimulation of cAMP-dependent protein kinase, and these effects were mimicked by inhibition of this activity. In permeabilized platelets, UK14304 and EPI potentiated InsP(3)-induced, CICR-mediated mobilization of Ca(2+) from internal stores in a similar way as did inhibition of cAMP-dependent protein kinase. In summary, a G(ialpha)-mediated decrease in cAMP level appears to play a major role in the platelet-activating effects of alpha(2A)-adrenergic receptor stimulation. Thus, in platelets, unlike other cell types, occupation of the G(ialpha)-coupled alpha(2A)-adrenergic receptors does not result in phospholipase C activation but rather in modulation of the Ca(2+) response by relieving cAMP-mediated suppression of InsP(3)-dependent CICR.

Inhibition of voltage-dependent calcium channels by prostaglandin E2 in rat melanotrophs.

The effects of PGE2 on voltage-dependent Ca2+ channel currents were studied in dissociated rat melanotrophs by the whole-cell configuration of the patch-clamp technique. In about 90% of melanotrophs examined, PGE2 reversibly inhibited voltage-dependent Ba2+ currents elicited by voltage steps from a holding potential of -80 to 0 mV, with an ED50 of 68 nM. The maximum inhibition of Ba2+ currents by 1 microM PGE2 (35.3%) was comparable with that by the maximally effective concentration (100 nM) of dopamine. The EP1/EP3 PGE (EP) agonists, 17PT-PGE2 and sulprostone, and the EP2/EP3 agonist, misoprostol, mimicked the inhibition by PGE2, whereas the selective EP2 agonist, butaprostol, had little effect. The inhibition by PGE2 was partially, but significantly, reduced by the selective EP1 antagonist, SC-51322. The magnitude of the PGE2-induced inhibition of Ba2+ currents was greatly reduced by pretreatment with pertussis toxin, or by a depolarizing prepulse, to +80 mV, lasting for 50 msec. Although four distinct types (N-, P/Q-, L-, and R-types) of high-threshold Ba2+ currents were observed, PGE2 (1 microM) caused significant inhibition of only P/Q- and L-type currents, which were 17.3 and 10.1%, respectively, of the total Ba2+ currents. These results suggest that PGE2 inhibits P/Q- and L-type Ca2+ channels of rat melanotrophs via EP1 and EP3 receptors, which are coupled to pertussis toxin-sensitive G proteins, and produces both voltage-sensitive and -insensitive inhibition of Ca2+ channels.

Renal sensory receptor activation causes prostaglandin-dependent release of substance P.

Renal mechanoreceptor (MR) activation by increased ureteral pressure (increases UP) results in an increase in afferent renal nerve activity (ARNA) that is blocked by substance P receptor blockade and prostaglandin (PG) synthesis inhibition. To examine the interaction between substance P and PGs, the release of substance P and PGE into the renal pelvis was studied before and during renal pelvic perfusion with indomethacin. Before indomethacin, increases UP increased ARNA 43 +/- 6% and renal pelvic release of substance P from 11 +/- 3 to 29 +/- 8 pg/min and PGE from 319 +/- 71 to 880 +/- 146 pg/min. Indomethacin blocked the increases in ARNA and release of substance P and PGE produced by increases UP. Time control experiments showed reproducible increases in ARNA and release of substance P and PGE during increases UP. Mechanical stimulation of the renal pelvic wall in vitro resulted in an increase in PGE release from 110 +/- 8 to 722 +/- 152 pg/min, which was abolished by indomethacin, suggesting a de novo PGE synthesis. The data suggest that increases UP results in a renal pelvic release of PGE, which facilitates the release of substance P and activation of renal pelvic MR.

Role of prostaglandin in the formation of osteoclasts induced by capsular-like polysaccharide antigen of Actinobacillus actinomycetemcomitans strain Y4.

We found no reports that capsular-like polysaccharide antigen purified from Actinobacillus actinomycetemcomitans either induces osteoclastic bone resorption in mouse organ cultures or promotes osteoclast formation in mouse marrow cultures. In contrast, capsular-like polysaccharide antigen purified from A. actinomycetemcomitans strain Y4 induced bone resorption in mouse organ culture. To examine the mechanism of bone resorption induced by A. actinomycetemcomitans, mouse bone marrow cells were cultured with A. actinomycetemcomitans strain Y4 capsular-like polysaccharide antigen. A. actinomycetemcomitans strain Y4 capsular-like polysaccharide antigen stimulated osteoclast-like cell formation in mouse bone marrow cultures. However, the polysaccharide of A. actinomycetemcomitans lipopolysaccharide did not induce the formation of osteoclast-like cells. Indomethacin inhibited osteoclast-like cell formation mediated by A. actinomycetemcomitans strain Y4 capsular-like polysaccharide antigen in a dose-dependent manner. There was a good correlation between the number of osteoclast-like cells formed in the marrow culture and the amount of prostaglandin E2 released into the culture media. When mouse bone marrow cells were cultured with prostaglandin E2 during the culture periods, many osteoclast-like cells were formed. These results indicate that prostaglandin E2 is involved in the mechanism of the formation of osteoclast-like cells mediated by A. actinomycetemcomitans strain Y4 capsular-like polysaccharide antigen. A. actinomycetemcomitans strain Y4 capsular-like polysaccharide antigen may play an important role in inflammatory bone resorption by promoting osteoclast formation in periodontal disease.

Characterization of receptors involved in the direct and indirect actions of prostaglandins E and I on the guinea-pig ileum.

1. A study of the effects of prostaglandin E2 (PGE2) and eleven synthetic analogues on the guinea-pig isolated ileum preparation has revealed three distinct contractile actions, each associated with a different prostaglandin E (EP-) receptor subtype. In addition, PGI2 (prostacyclin) and its stable analogues can activate prostaglandin I (IP-) receptors to elicit both contraction and relaxation of the ileum. 2. Two of the PGE actions involve direct stimulation of the smooth muscle, being unaffected by 1 microM morphine treatment. One action is blocked by AH 6809 at micromolar concentrations and ICI 80205 and 16,16-dimethyl PGE2 are particularly potent agonists. Activation of EP1-receptors appears to be involved. The second action is unaffected by AH 6809; sulprostone and MB 28767 are potent agonists. Comparison with agonist potency rankings on the guinea-pig vas deferens indicates that EP3-receptors may be involved. 3. The third PGE effect and the stimulant PGI effect are blocked by morphine, indicating enteric neurones and/or sensory nerve terminals as sites of action. EP2-receptors may be involved in the PGE action, in view of the marked effect of morphine on the contractile actions of misoprostol, 11-deoxy PGE2-1-alcohol, 11-deoxy PGE1 and butaprost, all of which show some selectivity for EP2-receptors. The PGI action is most easily studied with cicaprost (EC25 = 1.3 nM), since iloprost, carbacyclin and to a lesser extent PGI2 also have agonist activity at EP1-receptors. 4. The contractile action of 17-phenyl-omega-trinor PGE2 on the ileum is unaffected by morphine. Since this analogue shows only weak agonist activity on the rabbit jugular vein (EP2 preparation) and guinea-pig vas deferens (EP3), it may be a more useful standard agonist than PGE2 in EPl1-receptor studies.5. In the presence of morphine and AH 6809, cicaprost inhibits histamine-induced contractions (IC25 = 22 nM). PGI2 and iloprost show mixed inhibitory/potentiating actions, whereas carbacyclin only potentiates histamine contractions. This IP-receptor-mediated inhibition may account for the bell-shaped log concentration-response curve of cicaprost (no inhibitors present) and the very marked block of iloprostinduced contractions by AH 6809.6. We have found no evidence for either IP-receptors mediating direct contraction or EP-receptors mediating inhibition of the ileum longitudinal smooth muscle, as has been suggested in the literature.7. In view of the complexity of prostanoid action on the guinea-pig ileum we feel that the preparation must be used with caution to ascertain the EPl agonist or antagonist potencies of novel compounds.

Aspirin dose-dependently reduces alcohol-induced birth defects and prostaglandin E levels in mice.

The purpose of the present study was threefold. The first purpose was to determine if aspirin (ASA) decreases alcohol-induced birth defects in mice in a dose-dependent fashion. The second purpose was to see if the antagonism of alcohol-induced birth defects afforded by ASA pretreatment was related to dose-dependent decreases in prostaglandin E (PGE) levels in uterine/embryo tissue. The third purpose was to determine if ASA pretreatment altered maternal blood alcohol level. In experiments 1 and 2, pregnant C57BL/6J mice were administered ASA (0, 18.75, 37.5, 75, 150, or 300 mg/kg) on gestation day 10. One hour following the subcutaneous injection of ASA, mice received alcohol (5.8 g/kg) or an isocaloric sucrose solution intragastrically. In experiment 1 the incidence of birth defects was assessed in fetuses delivered by caesarean section on gestation day 19. In experiment 2 uterine/embryo tissue samples were collected on gestation day 10 1 hr following alcohol intubation for subsequent PGE analysis. In experiment 3 blood samples were taken at five time points following alcohol intubation from separate groups of alcohol-treated pregnant mice pretreated with 150 mg/kg ASA or vehicle. The results from the three experiments indicated that 1) ASA dose-dependently reduced the frequency of alcohol-induced birth defects in fetuses examined at gestation day 19, (2) ASA decreased the levels of PGE in gestation day 10 uterine/embryo tissue in a similar dose-dependent fashion, and 3) ASA pretreatment did not significantly influence maternal blood alcohol levels. These results provide additional support for the hypothesis that PGs may play an important role in mediating the teratogenic actions of alcohol.

A study of human calcitonin in an ovarian carcinoid and ovarian cancers.

High concentration of human calcitonin (hCT) was found in an ovarian carcinoid by radioimmunoassay. The hCT value was not affected by the presence of protease inhibitors. To confirm the presence of hCT in an ovarian carcinoid, hCT was isolated by the Baghdiantz method. The molecular weight of the ovarian hCT was determined using Sephadex G-75 gel filtration. Though the molecular weight of the ovarian hCT was variable, 90% corresponded to that of the authentic hCT. The carcinoid cells were examined by immunoperoxidase techniques. Those composed of strumal and trabecular structure were all argyrophilic, but hCT was only found in strumal structure. Significant concentrations of hCT were also found in ovarian cancers.