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Experimental Approach (experimental + approach)
Kinds of Experimental Approach Selected AbstractsTHE ,FRYING PANS' OF THE EARLY BRONZE AGE AEGEAN: AN EXPERIMENTAL APPROACH TO THEIR POSSIBLE USE AS LIQUID MIRRORS,ARCHAEOMETRY, Issue 4 2009D. A. PAPATHANASSOGLOU The so-called ,frying pans' are peculiar vessels, most of them made of terracotta, flat and shallow, usually decorated on the outside part and dated to the Early Bronze Age. They were unearthed mostly in the Cyclades, in Crete and on the Helladic mainland. There are also a few artefacts made of stone and of bronze, from the Cyclades and Asia Minor, respectively. The intended purpose of these objects is disputed. Several interpretations exist for their function, the earliest one being that of liquid mirror vessels. We investigated the mirror hypothesis experimentally, by testing trays with attributes similar to those of the original ,frying pans', filled with a series of liquids familiar to the people of the time and the place where those vessels were made. The criterion employed was the contrast of mirror images. We conclude that, provided that some minimal prerequisites are met, the ,frying pans' are quite appropriate as liquid mirror vessels. [source] Dual effect of nitric oxide on uterine prostaglandin synthesis in a murine model of preterm labourBRITISH JOURNAL OF PHARMACOLOGY, Issue 4 2010M Cella BACKGROUND AND PURPOSE Maternal infections are one of the main causes of adverse developmental outcomes including embryonic resorption and preterm labour. In this study a mouse model of inflammation-associated preterm delivery was developed, and used to study the relationship between nitric oxide (NO) and prostaglandins (PGs). EXPERIMENTAL APPROACH The murine model of preterm labour was achieved by assaying different doses of bacterial lipopolysaccharides (LPS). Once established, it was used to analyse uterine levels of prostaglandins E2 and F2, (by radioimmunoassay), cyclooxygenases (COX) and NOS proteins (by Western blot) and NO synthase (NOS) activity. Effects of inhibitors of COX and NOS on LPS-induced preterm labour were also studied. In vitro assays with a nitric oxide donor (SNAP) were performed to analyse the modulation of prostaglandin production by NO. KEY RESULTS Lipopolysaccharide increased uterine NO and PG synthesis and induced preterm delivery. Co-administration of meloxicam, a cyclooxygenase-2 inhibitor, or aminoguanidine, an inducible NOS inhibitor, prevented LPS-induced preterm delivery and blocked the increase in PGs and NO. Notably, the levels of NO were found to determine its effect on PG synthesis; low concentrations of NO reduced PG synthesis whereas high concentrations augmented them. CONCLUSIONS AND IMPLICATIONS An infection-associated model of preterm labour showed that preterm delivery can be prevented by decreasing PG or NO production. NO was found to have a dual effect on PG synthesis depending on its concentration. These data contribute to the understanding of the interaction between NO and PGs in pregnancy and parturition, and could help to improve neonatal outcomes. [source] Reduced signal transduction by 5-HT4 receptors after long-term venlafaxine treatment in ratsBRITISH JOURNAL OF PHARMACOLOGY, Issue 3 2010R Vidal BACKGROUND AND PURPOSE The 5-HT4 receptor may be a target for antidepressant drugs. Here we have examined the effects of the dual antidepressant, venlafaxine, on 5-HT4 receptor-mediated signalling events. EXPERIMENTAL APPROACH The effects of 21 days treatment (p.o.) with high (40 mg·kg,1) and low (10 mg·kg,1) doses of venlafaxine, were evaluated at different levels of 5-HT4 receptor-mediated neurotransmission by using in situ hybridization, receptor autoradiography, adenylate cyclase assays and electrophysiological recordings in rat brain. The selective noradrenaline reuptake inhibitor, reboxetine (10 mg·kg,1, 21 days) was also evaluated on 5-HT4 receptor density. KEY RESULTS Treatment with a high dose (40 mg·kg,1) of venlafaxine did not alter 5-HT4 mRNA expression, but decreased the density of 5-HT4 receptors in caudate-putamen (% reduction = 26 ± 6), hippocampus (% reduction = 39 ± 7 and 39 ± 8 for CA1 and CA3 respectively) and substantia nigra (% reduction = 49 ± 5). Zacopride-stimulated adenylate cyclase activation was unaltered following low-dose treatment (10 mg·kg,1) while it was attenuated in rats treated with 40 mg·kg,1 of venlafaxine (% reduction = 51 ± 2). Furthermore, the amplitude of population spike in pyramidal cells of CA1 of hippocampus induced by zacopride was significantly attenuated in rats receiving either dose of venlafaxine. Chronic reboxetine did not modify 5-HT4 receptor density. CONCLUSIONS AND IMPLICATIONS Our data indicate a functional desensitization of 5-HT4 receptors after chronic venlafaxine, similar to that observed after treatment with the classical selective inhibitors of 5-HT reuptake. [source] Disruption of gap junctions attenuates aminoglycoside-elicited renal tubular cell injuryBRITISH JOURNAL OF PHARMACOLOGY, Issue 8 2010Jian Yao BACKGROUND AND PURPOSE Gap junctions play important roles in the regulation of cell phenotype and in determining cell survival after various insults. Here, we investigated the role of gap junctions in aminoglycoside-induced injury to renal tubular cells. EXPERIMENTAL APPROACH Two tubular epithelial cell lines NRK-E52 and LLC-PK1 were compared for gap junction protein expression and function by immunofluorescent staining, Western blot and dye transfer assay. Cell viability after exposure to aminoglycosides was evaluated by WST assay. Gap junctions were modulated by transfection of the gap junction protein, connexin 43 (Cx43), use of Cx43 siRNA and gap junction inhibitors. KEY RESULTS NRK-E52 cells expressed abundant Cx43 and were functionally coupled by gap junctional intercellular communication (GJIC). Exposure of NRK-E52 cells to aminoglycosides, G418 and hygromycin, increased Cx43 phosphorylation and GJIC. The aminoglycosides also decreased cell viability that was prevented by gap junction inhibitors and Cx43 siRNA. LLC-PK1 cells were gap junction-deficient and resistant to aminoglycoside-induced cytotoxicity. Over-expression of a wild-type Cx43 converted LLC-PK1 cells to a drug-sensitive phenotype. The gap junction inhibitor ,-glycyrrhetinic acid (,-GA) activated Akt in NRK-E52 cells. Inhibition of the Akt pathway enhanced cell toxicity to G418 and abolished the protective effects of ,-GA. In addition, gentamycin-elicited cytotoxicity in NRK-E52 cells was also significantly attenuated by ,-GA. CONCLUSION AND IMPLICATIONS Gap junctions contributed to the cytotoxic effects of aminoglycosides. Modulation of gap junctions could be a promising approach for prevention and treatment of aminoglycoside-induced renal tubular cell injury. [source] Retail Store Lighting for Elderly Consumers: An Experimental ApproachFAMILY & CONSUMER SCIENCES RESEARCH JOURNAL, Issue 4 2007Nam-Kyu Park The study presents an investigation of the influence of the color of light on readability by figure to background value contrast, color perception, and overall room-light estimation for elderly consumers in an experimental setting representing a retail store. A factorial design with repeated measures was used to identify the impact of three independent variables: (a) lamp color temperatures, (b) lamp color-rendering properties, and (c) age of the participants. The results show that older adults perceived the higher color temperature light source as less cool than did younger adults. Older adults rated their level of comfort and preference higher than the younger participants under all lighting conditions. Regarding readability, higher color-rendering light sources provide better readability, and older adults have more difficulty with warmer lighting when value contrasts were reduced. Implications from this study can be applied to retail lighting techniques to attract elderly consumers. [source] Preference for Collpa Water by Frugivorous Bats (Artibeus): An Experimental ApproachBIOTROPICA, Issue 3 2010Adriana Bravo ABSTRACT Several species of stenodermatine bats congregate in large numbers at collpas in southeastern Peru to drink water. We conducted the first experimental tests of preference for collpa water by representative bats. Artibeus species preferred mineral-rich collpa water over water from other sources, supporting the hypothesis that they seek resources (especially sodium) at collpas. Abstract in Spanish is available at http://www.blackwell-synergy.com/loi/btp. [source] Consumer Perceptions of Promotional Offers in the Performing Arts: An Experimental ApproachCANADIAN JOURNAL OF ADMINISTRATIVE SCIENCES, Issue 3 2004Alain D'Astous This article reports the results of an experimental study in which four characteristics of sales promotions in the performing arts were manipulated: the type of promotion, the type of performance, the attractiveness of the performance, and the fit between the promotion and the performance. The results show that these factors had interactive effects on consumer reactions. Thus, although the fit between the promotion and the performance had a generally positive impact on consumer appreciation of the promotional offer, this effect was more important when the performance was more attractive. Sales promotions that closely fit the performing arts category were less likely to be perceived as manipulative when the performances were less attractive. We conclude that more research is needed on this managerially relevant topic in light of the complex dynamics that appear to underlie the relationships between the characteristics of sales promotions and consumer reactions. Résumé Cet article présente les résultats d'une étude expérimentale dans laquelle quatre facettes d'une promotion des ventes dans le contexte des arts de la scène ont été manipulées: le type de promotion, le type de performance, l'attrait de la performance et le lien entre la promotion et la performance. Les résultats montrent que ces facteurs ont des effets interactifs sur les réactions des consommateurs. Ainsi, même si le lien entre la promotion et la performance a un impact positif sur l'appréciation d'une offre promotionnelle, cet impact est plus important lorsque la performance est plus attrayante. Les promotions des ventes qui ont un lien fort avec le type d'art de la scène sont moins susceptibles d'être perçues comme des tentatives de manipulation. On conclut qu'il est nécessaire defaire plus de recherche sur ce sujet qui est pertinent pour les gestionnaires étant donné l'apparente complexité qui sous-tend les relations entre les caractéristiques des promotions des ventes et les réactions des consommateurs. [source] Alberta Consumers' Valuation of Extrinsic and Intrinsic Red Meat Attributes: A Choice Experimental ApproachCANADIAN JOURNAL OF AGRICULTURAL ECONOMICS, Issue 2 2010Bodo Steiner This paper analyzes Alberta consumers' perceptions toward extrinsic and intrinsic attributes of bison and beef steaks. In contrast to published Canadian consumer studies on bison meat that were undertaken prior to May 2003, before the first BSE case of Canadian origin was identified in beef cattle, this study provides a "post-BSE" assessment of consumer perceptions toward selected bison meat attributes. The results from an attribute-based choice experiment provide little support that simple traceability assurance schemes have value to consumers of bison and beef steaks, thus confirming similar findings of earlier beef studies that have employed different methodological approaches. The results also suggest that consumers are willing to pay significant premiums for bison steaks that are certified as being produced without genetically modified organisms, an attribute that has so far been unexplored in previous published bison studies. Le présent article analyse les perceptions des consommateurs de l'Alberta envers des attributs intrinsèques et extrinsèques du bifteck de b,uf et de bison. Contrairement aux études canadiennes sur la consommation de viande de bison publiées avant mai 2003, soit avant l'apparition du premier cas d'ESB dans un troupeau de bovins canadien, la présente étude livre une évaluation « post-ESB » des perceptions des consommateurs envers des attributs sélectionnés de la viande de bison. Les résultats obtenus à partir de la méthode des choix multi-attributs apportent peu d'appui à l'idée voulant que les mécanismes simples d'assurance de la traçabilité aient de la valeur pour les consommateurs de bifteck de bison et de b,uf, ce qui confirme les résultats similaires d'études antérieures sur le b,uf effectuées à l'aide de diverses approches méthodologiques. De plus, les résultats ont montré que les consommateurs sont prêts à payer un supplément appréciable pour du bifteck de bison certifié sans organisme génétiquement modifié (OGM), un attribut qui n'a pas été examiné dans les études sur le bison publiées antérieurement. [source] Combined in Silico and Experimental Approach for Drug Design: The Binding Mode of Peptidic and Non-Peptidic Inhibitors to Hsp90 N-Terminal DomainCHEMICAL BIOLOGY & DRUG DESIGN, Issue 5 2010Simona Tomaselli Heat shock protein 90 (Hsp90) is a prime target for antitumor therapies. The information obtained by molecular dynamics (MD) simulations is combined with NMR data to provide a cross-validated atomic resolution model of the complementary interactions of heat shock protein 90 with a peptidic (shepherdin) and a non-peptidic (5-aminoimidazole-4-carboxamide-1-,- d -ribofuranoside, AICAR) inhibitor, showing antiproliferative and proapoptotic activity in multiple tumor cell lines. This approach highlights the relevant role of imidazolic moiety in the interaction of both antagonist molecules. In 5-aminoimidazole-4-carboxamide-1-,- d -ribofuranoside bound state, one conformation of those present in solution is selected, where imidazolic, H4 and H5 protons have a key role in defining a non-polar region contacting heat shock protein 90 surface. The dynamic equilibrium between N-type and S-type puckered forms of 5-aminoimidazole-4-carboxamide-1-,- d -ribofuranoside moiety is shown to be functional to inhibitor binding. The first experimental structural data on these inhibitors are presented and discussed as hints for future design of improved molecules. [source] Experimental Approaches for Controlling Current Flowing through Metal,Molecule,Metal Junctions,ADVANCED MATERIALS, Issue 10 2006E. Tran Abstract Two experimental approaches that enable control of current flow through metal,molecules,metal junctions are described. A number of studies using two-electrode metal,molecules,metal junctions have shown that the current between the electrodes depends on the structures of the incorporated molecules. When a tunneling mechanism dominates electron transport through organic molecules, the molecules behave similar to resistors with resistivities that can be controlled by changing the structure. Incorporation of molecules with increasing conjugation into Hg-based junctions increases the current flow dramatically. Alternatively, by using four-electrode electrochemical junctions that allow the potential of the electrodes to be controlled with respect to the energy levels of the incorporated molecules, it is possible to change the mechanism of electron transfer and produce abrupt increases in the current flow. These signals, analogous to solid-state diodes, are particularly significant for molecular electronics. Electrochemical junctions also permit prediction of the value of the applied potential at which the current will start taking off and to identify the mechanism of charge transport. New and recently published results obtained using junctions based on Hg electrodes in an "electrochemical" mode show that two junctions incorporating redox centers by different interactions behave as current switches, with the current flow dominated by different charge-transport mechanisms. [source] Electrophysiological classification of P2X7 receptors in rat cultured neocortical astrogliaBRITISH JOURNAL OF PHARMACOLOGY, Issue 8 2010W Nörenberg Background and purpose:, P2X7 receptors are ATP-gated cation channels mediating important functions in microglial cells, such as the release of cytokines and phagocytosis. Electrophysiological evidence that these receptors also occur in CNS astroglia is rare and rather incomplete. Experimental approach:, We used whole-cell patch-clamp recordings to search for P2X7 receptors in astroglial,neuronal co-cultures prepared from the cerebral cortex of rats. Key results:, All the astroglial cells investigated responded to ATP with membrane currents, reversing around 0 mV. These currents could be also detected in isolated outside-out patch vesicles. The results of the experiments with the P2X [,,,-methylene ATP and 2,-3,-O-(4-benzoyl) ATP] and P2Y receptor agonists [adenosine 5,-O-(2-thiodiphosphate), uridine 5,-diphosphate, uridine 5,-triphosphate (UTP) and UDP-glucose] suggested the involvement of P2X receptors in this response. The potentiation of ATP responses in a low divalent cation or alkaline bath, but not by ivermectin, made it likely that a P2X7 receptor is operational. Blockade of the ATP effect by the P2X7 antagonists Brilliant Blue G, calmidazolium and oxidized ATP corroborated this assumption. Conclusions and implications:, Rat cultured cortical astroglia possesses functional P2X7 receptors. It is suggested that astrocytic P2X7 receptors respond to high local ATP concentrations during neuronal injury. [source] Ca2+ signalling by P2Y receptors in cultured rat aortic smooth muscle cellsBRITISH JOURNAL OF PHARMACOLOGY, Issue 8 2010Sriram Govindan Background and purpose:, P2Y receptors evoke Ca2+ signals in vascular smooth muscle cells and regulate contraction and proliferation, but the roles of the different P2Y receptor subtypes are incompletely resolved. Experimental approach:, Quantitative PCR was used to define expression of mRNA encoding P2Y receptor subtypes in freshly isolated and cultured rat aortic smooth muscle cells (ASMC). Fluorescent indicators in combination with selective ligands were used to measure the changes in cytosolic free [Ca2+] in cultured ASMC evoked by each P2Y receptor subtype. Key results:, The mRNA for all rat P2Y receptor subtypes are expressed at various levels in cultured ASMC. Four P2Y receptor subtypes (P2Y1, P2Y2, P2Y4 and P2Y6) evoke Ca2+ signals that require activation of phospholipase C and comprise both release of Ca2+ from stores and Ca2+ entry across the plasma membrane. Conclusions and implications:, Combining analysis of P2Y receptor expression with functional analyses using selective agonists and antagonists, we isolated the Ca2+ signals evoked in ASMC by activation of P2Y1, P2Y2, P2Y4 and P2Y6 receptors. [source] Sphingosine kinase 1 is critically involved in nitric oxide-mediated human endothelial cell migration and tube formationBRITISH JOURNAL OF PHARMACOLOGY, Issue 7 2010Stephanie Schwalm Background and purpose:, Sphingosine kinases (SKs) convert sphingosine to sphingosine 1-phosphate (S1P), which is a bioactive lipid that regulates a variety of cellular processes including proliferation, differentiation and migration. Experimental approach:, We used the human endothelial cell line EA.hy926 to investigate the effect of nitric oxide (NO) donors on SK-1 expression, and on cell migration and tube formation. Key results:, We showed that exposure of EA.hy926 cells to Deta-NO (125,1000 µM) resulted in a time- and concentration-dependent up-regulation of SK-1 mRNA and protein expression, and activity with a first significant effect at 250 µM of Deta-NO. The increased SK-1 mRNA expression resulted from an enhanced SK-1 promoter activity. A similar effect was also seen with various other NO donors. In mechanistic terms, the NO-triggered effect occurred independently of cGMP, but involved the classical mitogen-activated protein kinase cascade because the MEK inhibitor U0126 abolished the NO-induced SK-1 expression. The effect of NO was also markedly reduced by the thiol-reducing agent N -acetylcysteine, suggesting a redox-dependent mechanism. Functionally, Deta-NO triggered an increase in the migration of endothelial cells in an adapted Boyden chamber assay, and also increased endothelial tube formation in a Matrigel assay. These responses were both abolished in cells depleted of SK-1. Conclusions and implications:, These data show that NO donors up-regulate specifically SK-1 expression and activity in human endothelial cells, and SK-1 in turn critically contributes to the migratory capability and tube formation of endothelial cells. Thus, SK-1 may be considered an attractive novel target to interfere with pathological processes involving angiogenesis. [source] Spinal glial TLR4-mediated nociception and production of prostaglandin E2 and TNFBRITISH JOURNAL OF PHARMACOLOGY, Issue 7 2010O Saito Background and purpose:, Toll-like receptor 4 (TLR4) expressed on spinal microglia and astrocytes has been suggested to play an important role in the regulation of pain signalling. The purpose of the present work was to examine the links between TLR4, glial activation and spinal release of prostaglandin E2 (PGE2) and tumour necrosis factor (TNF), and the role these factors play in TLR4-induced tactile allodynia. Experimental approach:, Toll-like receptor 4 was activated by intrathecal (i.t.) injection of lipopolysaccharide (LPS) and KDO2 -Lipid A (KDO2) to rats. Tactile allodynia was assessed using von Frey filaments and cerebrospinal fluid collected through spinal dialysis and lumbar puncture. PGE2 and TNF levels were measured by mass spectometry and elisa. Minocycline and pentoxifylline (glia inhibitors), etanercept (TNF-blocker) and ketorolac (COX-inhibitor) were given i.t. prior to injection of the TLR4-agonists, in order to determine if these agents alter TLR4-mediated nociception and the spinal release of PGE2 and TNF. Key results:, Spinal administration of LPS and KDO2 produced a dose-dependent tactile allodynia, which was attenuated by pentoxifylline, minocycline and etanercept but not ketorolac. Both TLR4 agonists induced the spinal release of PGE2 and TNF. Intrathecal pentoxifylline blunted PGE2 and TNF release, while i.t. minocycline only prevented the spinal release of TNF. The release of PGE2 induced by LPS and KDO2 was attenuated by i.t. administration of ketorolac. Conclusions and implications:, Activation of TLR4 induces tactile allodynia, which is probably mediated by TNF released by activated spinal glia. [source] Expression and functional role of adenosine receptors in regulating inflammatory responses in human synoviocytesBRITISH JOURNAL OF PHARMACOLOGY, Issue 1 2010K Varani Background and purpose:, Adenosine is an endogenous modulator, interacting with four G-protein coupled receptors (A1, A2A, A2B and A3) and acts as a potent inhibitor of inflammatory processes in several tissues. So far, the functional effects modulated by adenosine receptors on human synoviocytes have not been investigated in detail. We evaluated mRNA, the protein levels, the functional role of adenosine receptors and their pharmacological modulation in human synoviocytes. Experimental approach:, mRNA, Western blotting, saturation and competition binding experiments, cyclic AMP, p38 mitogen-activated protein kinases (MAPKs) and nuclear factor (NF)-,B activation, tumour necrosis factor , (TNF-,) and interleukin-8 (IL-8) release were assessed in human synoviocytes isolated from patients with osteoarthritis. Key results:, mRNA and protein for A1, A2A, A2B and A3 adenosine receptors are expressed in human synoviocytes. Standard adenosine agonists and antagonists showed affinity values in the nanomolar range and were coupled to stimulation or inhibition of adenylyl cyclase. Activation of A2A and A3 adenosine receptors inhibited p38 MAPK and NF-,B pathways, an effect abolished by selective adenosine antagonists. A2A and A3 receptor agonists decreased TNF-, and IL-8 production. The phosphoinositide 3-kinase or Gs pathways were involved in the functional responses of A3 or A2A adenosine receptors. Synoviocyte A1 and A2B adenosine receptors were not implicated in the inflammatory process whereas stimulation of A2A and A3 adenosine receptors was closely associated with a down-regulation of the inflammatory status. Conclusions and implications:, These results indicate that A2A and A3 adenosine receptors may represent a potential target in therapeutic modulation of joint inflammation. [source] ,-Adrenoceptor stimulation potentiates insulin-stimulated PKB phosphorylation in rat cardiomyocytes via cAMP and PKABRITISH JOURNAL OF PHARMACOLOGY, Issue 1 2010Jorid T Stuenæs Background and purpose:, Genetic approaches have documented protein kinase B (PKB) as a pivotal regulator of heart function. Insulin strongly activates PKB, whereas adrenaline is not considered a major physiological regulator of PKB in heart. In skeletal muscles, however, adrenaline potentiates insulin-stimulated PKB activation without having effect in the absence of insulin. The purpose of the present study was to investigate the interaction between insulin and ,-adrenergic stimulation in regulation of PKB phosphorylation. Experimental approach:, Cardiomyocytes were isolated from adult rats by collagenase, and incubated with insulin, isoprenaline, and other compounds. Protein phosphorylation was evaluated by Western blot and phospho-specific antibodies. Key results:, Isoprenaline increased insulin-stimulated PKB Ser473 and Thr308 phosphorylation more than threefold in cardiomyocytes. Isoprenaline alone did not increase PKB phosphorylation. Isoprenaline also increased insulin-stimulated GSK-3, Ser9 phosphorylation approximately twofold, supporting that PKB phosphorylation increased kinase activity. Dobutamine (,1 -agonist) increased insulin-stimulated PKB phosphorylation as effectively as isoprenaline (more than threefold), whereas salbutamol (,2 -agonist) only potentiated insulin-stimulated PKB phosphorylation by approximately 80%. Dobutamine, but not salbutamol, increased phospholamban Ser16 phosphorylation and glycogen phosphorylase activation (PKA-mediated effects). Furthermore, the cAMP analogue that activates PKA (dibutyryl-cAMP and N6 -benzoyl-cAMP) increased insulin-stimulated PKB phosphorylation by more than threefold without effect alone. The Epac-specific activator 8-(4-chlorophenylthio)-2,-O-methyl-cAMP (007) increased insulin-stimulated PKB phosphorylation by approximately 50%. Db-cAMP and N6 -benzoyl-cAMP, but not 007, increased phospholamban Ser16 phosphorylation. Conclusions and implications:, ,-adrenoceptors are strong regulators of PKB phosphorylation via cAMP and PKA when insulin is present. We hypothesize that PKB mediates important signalling in the heart during ,-adrenergic receptors stimulation. [source] Obovatol attenuates microglia-mediated neuroinflammation by modulating redox regulationBRITISH JOURNAL OF PHARMACOLOGY, Issue 8 2010Jiyeon Ock Background and purpose:, Obovatol isolated from the medicinal herb Magnolia obovata exhibits a variety of biological activities. Here, the effect of obovatol and its mechanism of action on microglial activation, neuroinflammation and neurodegeneration were investigated. Experimental approach:, In microglial BV-2 cells stimulated with lipopolysaccharide (LPS), we measured nitric oxide (NO) and cytokine production, and activation of intracellular signalling pathways by reverse transcription-polymerase chain reaction and Western blots. Cell death was assayed in co-cultures of activated microglia (with bacterial LPS) and neurons and in LPS-induced neuroinflammation in mice in vivo. Key results:, Obovatol inhibited microglial NO production with an IC50 value of 10 µM. Obovatol also inhibited microglial expression of proinflammatory cytokines and inducible nitric-oxide synthase, which was accompanied by the inhibition of multiple signalling pathways such as nuclear factor kappa B, signal transducers and activators of transcription 1, and mitogen-activated protein kinases. In addition, obovatol protected cultured neurons from microglial toxicity and inhibited neuroinflammation in mice in vivo. One molecular target of obovatol in microglia was peroxiredoxin 2 (Prx2), identified by affinity chromatography and mass spectrometry. Obovatol enhanced the reactive oxygen species (ROS)-scavenging activity of Prx2 in vitro, thereby suppressing proinflammatory signalling pathways of microglia where ROS plays an important role. Conclusions and implications:, Obovatol is not only a useful chemical tool that can be used to investigate microglial signalling, but also a promising drug candidate against neuroinflammatory diseases. Furthermore, our results indicate that Prx2 is a novel drug target that can be exploited for the therapeutic modulation of neuroinflammatory signalling. [source] Augurin stimulates the hypothalamo-pituitary-adrenal axis via the release of corticotrophin-releasing factor in ratsBRITISH JOURNAL OF PHARMACOLOGY, Issue 8 2010JA Tadross Background and purpose:, The functional characterization of secreted peptides can provide the basis for the development of novel therapeutic agents. Augurin is a recently identified secreted peptide of unknown function expressed in multiple endocrine tissues, and in regions of the brain including the hypothalamus. We therefore investigated the effect of hypothalamic injection of augurin on the hypothalamo-pituitary-adrenal (HPA) axis in male Wistar rats. Experimental approach:, Augurin was given as a single injection into the third cerebral ventricle (i.c.v.) or into the paraventricular nucleus (iPVN) of the hypothalamus. Circulating hormone levels were then measured by radioimmunoassay. The effect of augurin on the release of hypothalamic neuropeptides was investigated ex vivo using hypothalamic explants. The acute effects of iPVN augurin on behaviour were also assessed. Key results:, i.c.v. injection of augurin significantly increased plasma ACTH and corticosterone, compared with vehicle-injected controls, but had no effect on other hypothalamo-pituitary axes hormones. Microinjection of lower doses of augurin into the PVN caused a similar increase in plasma ACTH and corticosterone, without significant alteration in behavioural patterns. Incubation of hypothalamic explants with increasing doses of augurin significantly elevated corticotrophin-releasing factor (CRF) and arginine vasopressin release. In vivo, peripheral injection of a CRF1/2 receptor antagonist prevented the rise in ACTH and corticosterone caused by i.c.v. augurin injection. Conclusions and implications:, These data suggest that augurin stimulates the release of ACTH via the release of hypothalamic CRF. Pharmacological manipulation of the augurin system may therefore be a novel target for regulation of the HPA axis. [source] Inhalational anaesthetics and n -alcohols share a site of action in the neuronal Shaw2 Kv channelBRITISH JOURNAL OF PHARMACOLOGY, Issue 7 2010Aditya Bhattacharji Background and purpose:, Neuronal ion channels are key targets of general anaesthetics and alcohol, and binding of these drugs to pre-existing and relatively specific sites is thought to alter channel gating. However, the underlying molecular mechanisms of this action are still poorly understood. Here, we investigated the neuronal Shaw2 voltage-gated K+ (Kv) channel to ask whether the inhalational anaesthetic halothane and n -alcohols share a binding site near the activation gate of the channel. Experimental approach:, Focusing on activation gate mutations that affect channel modulation by n -alcohols, we investigated n -alcohol-sensitive and n -alcohol-resistant Kv channels heterologously expressed in Xenopus oocytes to probe the functional modulation by externally applied halothane using two-electrode voltage clamping and a gas-tight perfusion system. Key results:, Shaw2 Kv channels are reversibly inhibited by halothane in a dose-dependent and saturable manner (K0.5= 400 µM; nH= 1.2). Also, discrete mutations in the channel's S4S5 linker are sufficient to reduce or confer inhibition by halothane (Shaw2-T330L and Kv3.4-G371I/T378A respectively). Furthermore, a point mutation in the S6 segment of Shaw2 (P410A) converted the halothane-induced inhibition into halothane-induced potentiation. Lastly, the inhibition resulting from the co-application of n -butanol and halothane is consistent with the presence of overlapping binding sites for these drugs and weak binding cooperativity. Conclusions and implications:, These observations strongly support a molecular model of a general anaesthetic binding site in the Shaw2 Kv channel. This site may involve the amphiphilic interface between the S4S5 linker and the S6 segment, which plays a pivotal role in Kv channel activation. [source] Genistein potentiates activity of the cation channel TRPC5 independently of tyrosine kinasesBRITISH JOURNAL OF PHARMACOLOGY, Issue 7 2010Ching-On Wong Background and purpose:, TRPC5 is a Ca2+ -permeable channel with multiple modes of activation. We have explored the effects of genistein, a plant-derived isoflavone, on TRPC5 activity, and the mechanism(s) involved. Experimental approach:, Effects of genistein on TRPC5 channels were investigated in TRPC5-over-expressing human embryonic kidney 293 (HEK) cells and bovine aortic endothelial cells (BAECs) using fluorescent Ca2+ imaging and electrophysiological techniques. Key results:, In TRPC5-over-expressing HEK cells, genistein stimulated TRPC5-mediated Ca2+ influx, concentration dependently (EC50= 93 µM). Genistein and lanthanum activated TRPC5 channels synergistically. Effects of genistein on TRPC5 channels were mimicked by daidzein (100 µM), a genistein analogue inactive as a tyrosine kinase inhibitor, but not by known tyrosine kinase inhibitors herbimycin (2 µM), PP2 (20 µM) and lavendustin A (10 µM). Action of genistein on TRPC5 channels was not affected by an oestrogen receptor inhibitor ICI-182780 (50 µM) or a phospholipase C inhibitor U73122 (10 µM), suggesting genistein did not act through oestrogen receptors or phospholipase C. In BAECs, genistein (100 µM) stimulated TRPC5-mediated Ca2+ influx. In patch clamp studies, both genistein (50 µM) and daidzein (50 µM) augmented TRPC5-mediated whole-cell cation current in TRPC5 over-expressing HEK cells. Genistein stimulated TRPC5 channel activity in excised inside-out membrane patch, suggesting that its action was relatively direct and did not require cytosolic factors. Conclusions and implications:, The present study is the first to demonstrate stimulation of a TRP channel by isoflavones. Genistein is a lipophilic compound able to stimulate TRPC5 activity in TRPC5-over-expressing HEK cells and in native vascular endothelial cells. [source] Binding of GTP,[35S] is regulated by GDP and receptor activation.BRITISH JOURNAL OF PHARMACOLOGY, Issue 6 2010Studies with the nociceptin/orphanin FQ receptor Background and purpose:, We have examined the effects of ligand efficacy and receptor density on the binding of guanosine 5,-[,-thio]triphosphate (GTP,S) and GDP to the nociceptin/orphanin FQ (N/OFQ) peptide receptor (NOP)-coupled G-proteins. Experimental approach:, In GTP,[35S] binding experiments, using stable (CHOhNOP) and inducible (CHOINDhNOP) recombinant human and rat NOP we have measured: (i) ligand-specific GDP requirements; (ii) the effects of receptor density on guanine nucleotide affinity/capacity; and (iii) the effect of ligand efficacy on GTP,S association kinetics. Key results:, GTP,S competition curves were shallow and modelled by high- and low-affinity components that were relatively consistent between cell types and tissue preparations. In the presence of 1 µM N/OFQ a high-affinity GDP binding site was also present, but the fraction of total binding was reduced. In an efficacy-dependent manner, the partial agonists [F/G]N/OFQ(1-13)NH2 ([Phe1,(CH2 -NH)Gly2]-nociceptin(1-13)NH2) and naloxone benzoylhydrazone both reduced the fraction of high-affinity sites for GDP (relative to basal). While the pIC50 for high-affinity GDP binding site did not decrease in the presence of 1 µM N/OFQ, N/OFQ produced a significant reduction in pIC50 for the low-affinity site. Agonist-mediated decrease in affinity for GDP binding was efficacy-dependent. GDP displayed three affinities: high, conserved in the presence and absence of ligand; intermediate, present as a low fraction under basal conditions; low (efficacy-dependent), present during receptor activation representing the majority of binding. Conclusions and implications:, The affinity of GTP,[35S] was regulated by GDP and receptor activation caused increased binding of GTP,[35S] through a reduction in GDP affinity. [source] Statins suppress interleukin-6-induced monocyte chemo-attractant protein-1 by inhibiting Janus kinase/signal transducers and activators of transcription pathways in human vascular endothelial cellsBRITISH JOURNAL OF PHARMACOLOGY, Issue 6 2010Michihisa Jougasaki Background and purpose:, The mechanisms of anti-inflammatory actions of statins, 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase inhibitors, remain unclear. We investigated the effects of statins on interleukin (IL)-6-induced monocyte chemo-attractant protein (MCP)-1 expression and monocyte chemotaxis. Experimental approach:, Cultures of human aortic endothelial cells (HAECs) were stimulated with IL-6 in the absence and presence of statins. Gene expression and protein secretion of MCP-1, phosphorylation of Janus kinase (JAK) and the signal transducers and activators of transcription (STAT) pathway, and human monocyte migration were examined. Key results:, IL-6 plus its soluble receptor sIL-6R (IL-6/sIL-6R) promoted THP-1 monocyte migration, and increased gene expression and protein secretion of MCP-1, more than IL-6 alone or sIL-6R alone. Various statins inhibited IL-6/sIL-6R-promoted monocyte migration and MCP-1 expression in HAECs. Co-incubation of mevalonate and geranylgeranyl pyrophosphate, but not farnesyl pyrophosphate, reversed the inhibitory effects of statins on MCP-1 expression. Geranylgeranyl transferase inhibitor, but not farnesyl transferase inhibitor, suppressed IL-6/sIL-6R-stimulated MCP-1 expression. IL-6/sIL-6R rapidly phosphorylated JAK1, JAK2, TYK2, STAT1 and STAT3, which were inhibited by statins. Transfection of STAT3 small interfering RNA (siRNA), but not STAT1 siRNA, attenuated the ability of IL-6/sIL-6R to enhance THP-1 monocyte migration. In addition, statins blocked IL-6/sIL-6R-induced translocation of STAT3 to the nucleus. Conclusions and implications:, Statins suppressed IL-6/sIL-6R-induced monocyte chemotaxis and MCP-1 expression in HAECs by inhibiting JAK/STAT signalling cascades, explaining why statins have anti-inflammatory properties beyond cholesterol reduction. [source] Genistein reduces glycosaminoglycan levels in a mouse model of mucopolysaccharidosis type IIBRITISH JOURNAL OF PHARMACOLOGY, Issue 5 2010A Friso Background and purpose:, Mucopolysaccharidoses (MPS) are lysosomal storage disorders resulting from a deficit of specific lysosomal enzymes catalysing glycosaminoglycan (GAG) degradation. The typical pathology involves most of the organ systems, including the brain, in its severe forms. The soy isoflavone genistein has recently attracted considerable attention as it can reduce GAG synthesis in vitro. Furthermore, genistein is able to cross the blood,brain barrier in the rat. The present study was undertaken to assess the ability of genistein to reduce urinary and tissue GAG levels in vivo. Experimental approach:, We used mice with genetic deletion of iduronate-2-sulphatase (one of the GAG catabolizing enzymes) which provide a model of MPS type II. Two doses of genistein, 5 or 25 mg·kg,1·day,1, were given, in the diet for 10 or 20 weeks. Urinary and tissue GAG content was evaluated by biochemical and histochemical procedures. Key results:, Urinary GAG levels were reduced after 10 weeks' treatment with genistein at either 5 or 25 mg·kg,1·day,1. In tissue samples from liver, spleen, kidney and heart, a reduction in GAG content was observed with both dosages, after 10 weeks' treatment. Decreased GAG deposits in brain were observed after genistein treatment in some animals. Conclusions and implications:, There was decreased GAG storage in the MPSII mouse model following genistein administration. Our results would support the use of this plant-derived isoflavone in a combined therapeutic protocol for treatment of MPS. [source] Distinct expression and ligand-binding profiles of two constitutively active GPR17 splice variantsBRITISH JOURNAL OF PHARMACOLOGY, Issue 5 2010T Benned-Jensen Background and purpose:, In humans and non-human primates, the 7TM receptor GPR17 exists in two isoforms differing only by the length of the N-terminus. Of these, only the short isoform has previously been characterized. Hence, we investigated gene expression and ligand-binding profiles of both splice variants and furthermore uncovered and characterized constitutive activity of both isoforms. Experimental approach:, Expression levels of the hGPR17 isoforms were determined in several brain regions as well as heart and kidney using quantitative RT-PCR. A CREB reporter assay and [35S]-GTP,S binding were employed to assess the constitutive activity and the activation by UDP, UDP-glucose and -galactose and the cysteinyl leukotrienes LTC4 and LTD4. Leukotriene binding and induction of internalization were furthermore tested using homologous competition binding and antibody-feeding experiments respectively. Key results:, The short isoform (hGPR17-S) was expressed more abundantly (eight- to 23-fold) in the brain than the long isoform (hGPR17-L), whereas the opposite was observed in heart and kidney. As previously reported, the uracil nucleotides activated hGPR17-S with micromolar potencies. However, much lower potencies were observed for hGPR17-L with a 50- to 170-fold increase in EC50. Furthermore, contrary to previous reports, neither of the isoforms was activated or bound by the cysteinyl leukotrienes. Finally, both receptors were demonstrated to be constitutively active through G,i. Conclusions and implications:, We present the first isoform-specific characterization of GPR17 and show that differences exist between the isoforms, in both expression pattern and pharmacological profile. In turn, our results indicate that the two human isoforms might serve tissue-specific functions. [source] In vitro and in vivo antineoplastic activity of a novel bromopyrrole and its potential mechanism of actionBRITISH JOURNAL OF PHARMACOLOGY, Issue 4 2010Sheng Xiong Background and purpose:, Many bromopyrrole compounds have been reported to have in vitro antineoplastic activity. In a previous study, we isolated N-(4, 5-dibromo-pyrrole-2-carbonyl)-L-amino isovaleric acid methyl ester (B6) from marine sponges. Here, we investigated the in vitro and in vivo antineoplastic activity of B6 and its potential mechanism. Experimental approach:, The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was used to determine the in vitro antineoplastic activity of B6. Flow cytometry, western blot analysis and morphological observations were used to investigate its mechanism of action. A mouse xenograft model was used to determine its in vivo activity. Key results:, B6 inhibited the proliferation of various human cancer cells in vitro, with highest activity on LOVO and HeLa cells. B6 also exhibited significant growth inhibitory effects in vivo in a xenograft mouse model. Acute toxicity analysis suggested that B6 has low toxicity. B6-treated cells arrested in the G1 phase of the cell cycle and had an increased fraction of sub-G1 cells. In addition, the population of Annexin V-positive/propidium iodide-negative cells increased, indicating the induction of early apoptosis. Indeed, B6-treated cells exhibited morphologies typical of cells undergoing apoptosis. Western blotting showed cleaved forms of caspase-9 and caspase-3 in cells exposed to B6. Moreover, B6-promoted Ca2+ release and apoptosis was associated with elevated intracellular Ca2+concentration. Conclusions and implications:, B6 has significant antineoplastic activity in vitro as well as in vivo. It inhibits tumour cell proliferation by arresting the cell cycle and inducing apoptosis. With its low toxicity, B6 represents a promising antineoplastic, primary compound. [source] Thrombin activation of proteinase-activated receptor 1 potentiates the myofilament Ca2+ sensitivity and induces vasoconstriction in porcine pulmonary arteriesBRITISH JOURNAL OF PHARMACOLOGY, Issue 4 2010Jun Maki Background and purpose:, Thrombus formation is commonly associated with pulmonary arterial hypertension (PAH). Thrombin may thus play an important role in the pathogenesis and pathophysiology of PAH. Hence, we investigated the contractile effects of thrombin and its mechanism in pulmonary artery. Experimental approach:, The cytosolic Ca2+ concentrations ([Ca2+]i), 20 kDa myosin light chain (MLC20) phosphorylation and tension development were evaluated using the isolated porcine pulmonary artery. Key results:, Thrombin induced a sustained contraction in endothelium-denuded strips obtained from different sites of a pulmonary artery, ranging from the main pulmonary artery to the intrapulmonary artery. In the presence of endothelium, thrombin induced a transient relaxation. The contractile effect of thrombin was abolished by either a protease inhibitor or a proteinase-activated receptor 1 (PAR1) antagonist, while it was mimicked by PAR1 -activating peptide (PAR1AP), but not PAR4AP. The thrombin-induced contraction was associated with a small elevation of [Ca2+]i and an increase in MLC20 phosphorylation. Thrombin and PAR1AP induced a greater increase in tension for a given [Ca2+]i elevation than that obtained with high K+ -depolarization. They also induced a contraction at a fixed Ca2+ concentration in ,-toxin-permeabilized preparations. Conclusions and implications:, The present study revealed a unique property of the pulmonary artery. In contrast to normal arteries of the systemic circulation, thrombin induces a sustained contraction in the normal pulmonary artery, by activating PAR1 and thereby increasing the sensitivity of the myofilament to Ca2+. This responsiveness of the pulmonary artery to thrombin may therefore contribute to the pathogenesis and pathophysiology of PAH. [source] Dog left ventricular midmyocardial myocytes for assessment of drug-induced delayed repolarization: short-term variability and proarrhythmic potentialBRITISH JOURNAL OF PHARMACOLOGY, Issue 1 2010Najah Abi-Gerges Background and purpose:, Evaluation of the potential for delayed ventricular repolarization and proarrhythmia by new drugs is essential. We investigated if dog left ventricular midmyocardial myocytes (LVMMs) that can be used as a preclinical model to assess drug effects on action potential duration (APD) and whether in these cells, short-term variability (STV) or triangulation could predict proarrhythmic potential. Experimental approach:, Beagle LVMMs and Purkinje fibres (PFs) were used to record APs. Effects of six reference drugs were assessed on APD at 50% (APD50) and 90% (APD90) of repolarization, STV(APD), triangulation (ratio APD90/APD50) and incidence of early afterdepolarizations (EADs) at 1 and 0.5 Hz. Key results:, LVMMs provided stable recordings of AP, which were not affected by four sequential additions of dimethyl sulphoxide. Effects of dofetilide, d-sotalol, cisapride, pinacidil and diltiazem, but not of terfenadine, on APD in LVMMs were found to be comparable with those recorded in PFs. LVMMs, but not PFs, exhibited a proarrhythmic response to IKr blockers. Incidence of EADs was not related to differences in AP prolongation or triangulation, but corresponded to beat-to-beat variability of repolarization, here quantified as STV of APD. Conclusions and implications:, LVMMs provide a suitable preclinical model to assess the effects of new drugs on APD and also yield additional information about putative indicators of proarrhythmia that add value to an integrated QT/TdP risk assessment. Our findings support the concept that increased STV(APD) may predict drug-induced proarrhythmia. This article is part of a themed section on QT safety. To view this issue visit http://www3.interscience.wiley.com/journal/121548564/issueyear?year=2010 [source] Pharmacokinetic,pharmacodynamic modelling of the analgesic effects of lumiracoxib, a selective inhibitor of cyclooxygenase-2, in ratsBRITISH JOURNAL OF PHARMACOLOGY, Issue 1 2010DA Vásquez-Bahena Background and purpose:, This study establishes a pharmacokinetic/pharmacodynamic (PK/PD) model to describe the time course and in vivo mechanisms of action of the antinociceptive effects of lumiracoxib, evaluated by the thermal hyperalgesia test in rats. Experimental approach:, Female Wistar fasted rats were injected s.c. with saline or carrageenan in the right hind paw, followed by either 0, 1, 3, 10 or 30 mg·kg,1 of oral lumiracoxib at the time of carrageenan injection (experiment I), or 0, 10 or 30 mg·kg,1 oral lumiracoxib at 4 h after carrageenan injection (experiment II). Antihyperalgesic responses were measured as latency time (LT) to a thermal stimulus. PK/PD modelling of the antinociceptive response was performed using the population approach with NONMEM VI. Results:, A two-compartment model described the plasma disposition. A first-order model, including lag time and decreased relative bioavailability as a function of the dose, described the absorption process. The response model was: LT=LT0/(1 +MED). LT0 is the baseline response, and MED represents the level of inflammatory mediators. The time course of MED was assumed to be equivalent to the predicted profile of COX-2 activity and was modelled according to an indirect response model with a time variant synthesis rate. Drug effects were described as a reversible inhibition of the COX-2 activity. The in vivo estimate of the dissociation equilibrium constant of the COX-2-lumiracoxib complex was 0.24 µg·mL,1. Conclusions:, The model developed appropriately described the time course of pharmacological responses to lumiracoxib, in terms of its mechanism of action and pharmacokinetics. [source] Mechanisms involved in the regulation of bovine pulmonary vascular tone by the 5-HT1B receptorBRITISH JOURNAL OF PHARMACOLOGY, Issue 1 2010C McKenzie Background and purpose:, 5-HT1B receptors may have a role in pulmonary hypertension. Their relationship with the activity of BKCa, a T-type voltage-operated calcium channel (VOCC) and cyclic nucleotide-mediated relaxation was examined. Experimental approach:, Ring segments of bovine pulmonary arteries were mounted in organ baths in modified Krebs,Henseleit buffer (37oC) under a tension of 20 mN and gassed with 95% O2/5% CO2. Isometric recordings were made using Chart 5 software. Key results:, Contractile responses to 5-HT (10 nM,300 µM) were inhibited similarly by the 5-HT1B receptor antagonist SB216641 (100 nM) and the T-type VOCC blockers mibefradil (10 µM) and NNC550396 (10 µM) with no additive effect between SB216641 and mibefradil. Inhibition by SB216641 was prevented by the potassium channel blocker, charybdotoxin (100 nM). 5-HT1B receptor activation and charybdotoxin produced a mibefradil-sensitive potentiation of responses to U46619. Bradykinin (0.1 nM,30 µM), sodium nitroprusside (0.01 nM,3 µM), zaprinast (1 nM,3 µM), isoprenaline (0.1 nM,10 µM) and rolipram (1 nM,3 µM) produced 50% relaxation of arteries constricted with 5-HT (1,3 µM) or U46619 (30,50 nM) in the presence of 5-HT1B receptor activation, but full relaxation of arteries constricted with U46619, the 5-HT2A receptor agonist 2,5 dimethoxy-4 iodoamphetamine (1 µM) or 5-HT in the presence of 5-HT1B receptor antagonism. Enhanced relaxation of 5-HT-constricted arteries by cGMP-dependent pathways, seen in the presence of the 5-HT1B receptor antagonist, was reversed by charybdotoxin whereas cAMP-dependent relaxation was only partly reversed by charybdotoxin. Conclusions and implications:, 5-HT1B receptors couple to inhibition of BKCa, thus increasing tissue sensitivity to contractile agonists by activating a T-type VOCC and impairing cGMP-mediated relaxation. Impaired cAMP-mediated relaxation was only partly mediated by inhibition of BKCa. [source] Positive allosteric modulation of ,7 neuronal nicotinic acetylcholine receptors: lack of cytotoxicity in PC12 cells and rat primary cortical neuronsBRITISH JOURNAL OF PHARMACOLOGY, Issue 8 2009Min Hu Background and purpose:, ,7-Nicotinic acetylcholine receptors (,7 nAChRs) play an important role in cognitive function. Positive allosteric modulators (PAMs) amplify effects of ,7 nAChR agonist and could provide an approach for treatment of cognitive deficits in neuropsychiatric diseases. PAMs can either predominantly affect the apparent peak current response (type I) or increase both the apparent peak current response and duration of channel opening, due to prolonged desensitization (type II). The delay of receptor desensitization by type II PAMs raises the possibility of Ca2+ -induced toxicity through prolonged activation of ,7 nAChRs. The present study addresses whether type I and II PAMs exhibit different cytotoxicity profiles. Experimental approach:, The present studies evaluated cytotoxic effects of type I PAM [N-(4-chlorophenyl)]-,-[(4-chloro-phenyl)-aminomethylene]-3-methyl-5-isoxazoleacet-amide (CCMI) and type II PAM 1-[5-chloro-2,4-dimethoxy-phenyl]-3-[5-methyl-isoxazol-3-yl]-urea (PNU-120596), or 4-[5-(4chloro-phenyl)-2-methyl-3-propionyl-pyrrol-1-yl]-benzenesulphonamide (A-867744). The studies used cultures of PC12 cells and primary cultures of rat cortical neuronal cells. Key results:, Our results showed that neither type I nor type II PAMs had any detrimental effect on cell integrity or cell viability. In particular, type II PAMs did not affect neuron number and neurite outgrowth under conditions when ,7 nAChR activity was measured by Ca2+ influx and extracellular signal-regulated kinases 1 and 2 phosphorylation, following exposure to ,7 nAChR agonists. Conclusions and implications:, This study demonstrated that both type I and type II ,7 nAChR selective PAMs, although exhibiting differential electrophysiological profiles, did not exert cytotoxic effects in cells endogenously expressing ,7 nAChRs. [source] | ||||||||||||||||||||||||||||||||||||||||