Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0043167 (pertussis)
 19,595 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The human peripheral cannabinoid (CB2) receptor has been cloned by reverse transcription-polymerase chain reaction from human spleen RNA and expressed, to study both ligand binding characteristics and signal transduction pathways. Receptor binding assays used the aminoalkylindole [3H]Win 55212-2 and membranes from transiently transfected COS-M6 cells. Saturation analysis showed that [3H]Win 55212-2 specific binding to the CB2 receptor was of high affinity, with a Kd of 2.1 +/- 0.2 nM (four experiments), and a high level of expression was attained, with a maximal number of saturable binding sites of 24.1 +/- 4.4 pmol/mg of protein (four experiments). The rates of association and dissociation for [3H]Win 55212-2 specific binding were both rapid when measured at 30 degrees. [3H]Win 55212-2 specific binding to the CB2 receptor was moderately enhanced by divalent and monovalent cations but was only slightly inhibited by guanosine-5'-O-(3-thio)-triphosphate. Competition for [3H]Win 55212-2 specific binding to the CB2 receptor was stereoselective, with the following rank order of potency for the more active stereoisomers: HU-210 > (-)-CP-55940 approximately Win 55212-2 >> (-)delta 9-THC > anandamide. The signaling pathway of the human CB2 receptor was investigated in a CB2-CHO-K1 stable cell line. CB2 receptor activation by cannabinoid agonists inhibited forskolin-induced cAMP production in a concentration-dependent and stereoselective manner but did not increase either cAMP production or Ca2+ mobilization in fura-2/acetoxymethyl ester-loaded CB2-CHO-K1 cells. The CB2 receptor-mediated inhibition of forskolin-induced cAMP production was abolished by pretreatment of the cells with 10 ng/ml pertussis toxin. These results demonstrate that the CB2 receptor is functionally coupled to inhibition of adenylyl cyclase activity via a pertussis toxin-sensitive G protein.
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PMID:Activation of the human peripheral cannabinoid receptor results in inhibition of adenylyl cyclase. 765 69

Activation of cannabinoid receptors inhibits voltage-gated Ca2+ channels and activates K+ channels, reminiscent of other G-protein-coupled signaling pathways that produce presynaptic inhibition. We tested cannabinoid receptor agonists for effects on excitatory neurotransmission between cultured rat hippocampal neurons. Reducing the extracellular Mg2+ concentration to 0.1 mM elicited repetitive, transient increases in intracellular Ca2+ concentration ([Ca2+]i spikes) that resulted from bursts of action potentials, as measured by combined whole-cell current clamp and indo-1-based microfluorimetry. Pharmacological characterization indicated that the [Ca2+]i spikes required glutamatergic synaptic transmission. Cannabinoid receptor ligands inhibited stereoselectively the frequency of [Ca2+]i spiking in the rank order of potency: CP 54,939 > CP 55,940 > Win 55,212-2 > anandamide, with EC50 values of 0.36, 1.2, 2.7, and 71 nM, respectively. CP 55,940 was potent, but not efficacious, and reversed the inhibition produced by Win 55,212-2, indicating that it is a partial agonist. Inhibition of [Ca2+]i spiking by Win 55,212-2 was prevented by treatment of cultures with active, but not heat-treated, pertussis toxin. Win 55,212-2 (100 nM) inhibited stereoselectively CNQX-sensitive excitatory postsynaptic currents (EPSCs) elicited by presynaptic stimulation with an extracellular electrode, but did not affect the presynaptic action potential or currents elicited by direct application of kainate. Consistent with a presynaptic site of action, Win 55,212-2 increased both the number of response failures and the coefficient of variation of the evoked EPSCs. In contrast, cannabimimetics did not affect bicuculline-sensitive inhibitory postsynaptic currents. Thus, activation of cannabinoid receptors inhibits the presynaptic release of glutamate via an inhibitory G-protein.
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PMID:Cannabinoid receptor agonists inhibit glutamatergic synaptic transmission in rat hippocampal cultures. 869 43

Cerebellar granule cells (CGCs) express the CB(1) subtype of cannabinoid receptor. CB(1) receptor agonists Win 55212-2, CP55940 and HU210 inhibit KCl-induced activation of nitric oxide synthase (NOS) in CGCs. Win 55212-2 has no effect on either basal NOS activity or on activation by N-methyl-D-aspartate and its effect is abolished by pre-treatment of the cells with pertussis toxin. The CB(1) receptor antagonist/inverse agonist SR141716A both reverses the effects of Win 55212-2 and produces an increase in NOS activity that is additive with KCl. These results support the hypothesis that activation of the CB(1) receptor in CGCs results in a decreased influx of calcium in response to membrane depolarization, resulting in a decreased activation of neuronal NOS.
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PMID:Effects of CB(1) cannabinoid receptor activation on cerebellar granule cell nitric oxide synthase activity. 1051 35

Neuronal cannabinoid receptors (CB(1)) are coupled to inhibition of voltage-sensitive Ca(2+) channels (VSCCs) in several cell types. The purpose of these studies was to characterize the interaction between endogenous CB(1) receptors and VSCCs in cerebellar granule neurons (CGN). Ca(2+) transients were evoked by KCl-induced depolarization and imaged using fura-2. The CB(1) receptor agonists CP55940, Win 55212-2 and N-arachidonylethanolamine (anandamide) produced concentration-related decreases in peak amplitude of the Ca(2+) response and total Ca(2+) influx. Pre-treatment of CGN with pertussis toxin abolished agonist-mediated inhibition. The inhibitory effect of Win 55212-2 on Ca(2+) influx was additive with inhibition produced by omega-agatoxin IVA and nifedipine but not with omega-conotoxin GVIA, indicating that N-type VSCCs are the primary effector. Paradoxically, the CB(1) receptor antagonist, SR141716, also inhibited KCl-induced Ca(2+) influx into CGN in a concentration-related manner. SR141716 inhibition was pertussis toxin-insensitive and was not additive with the inhibition produced by Win 55212-2. Confocal imaging of CGN in primary culture demonstrate a high density of CB(1) receptor expression on CGN plasma membranes, including the neuritic processes. These data demonstrate that the CB(1) receptor is highly expressed by CGN and agonists serve as potent and efficacious inhibitory modulators of Ca(2+) influx through N-type VSCC.
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PMID:Cannabinoid receptor agonists inhibit depolarization-induced calcium influx in cerebellar granule neurons. 1167 65

Cannabinoids exert pleiotropic actions in the CNS, including the inhibition of inflammatory responses and the enhancement of neuronal survival after injury. Although cannabinoid receptors are distributed widely in brain, their presence has not been investigated previously in oligodendrocytes. This study examined the expression of cannabinoid type 1 (CB1) receptors in rat oligodendrocytes in vivo and in culture and explored their biological function. Expression of CB1 receptors by oligodendrocytes was demonstrated immunocytochemically in postnatal and in adult white matter as well as in oligodendrocyte cultures. Reverse transcription-PCR and Western blotting further confirmed the presence of CB1 receptors. Oligodendrocyte progenitors undergo apoptosis with the withdrawal of trophic support, as determined by TUNEL assay and caspase-3 activation, and both the selective CB1 agonist arachidonyl-2'-chloroethylamide/(all Z)-N-(2-cycloethyl)-5,8,11,14-eicosatetraenamide (ACEA) and the nonselective cannabinoid agonists HU210 and (+)-Win-55212-2 enhanced cell survival. To investigate intracellular signaling involved in cannabinoid protection, we focused on the phosphatidylinositol-3 kinase (PI3K)/Akt pathway. HU210, (+)-Win-55212-2, and ACEA elicited a time-dependent phosphorylation of Akt. Pertussis toxin abolished Akt activation, indicating the involvement of G(i)/G(o)-protein-coupled receptors. The CB1 receptor antagonist SR141716A partially inhibited Akt phosphorylation in response to HU210 and (+)-Win-55212-2 and abolished the effects of ACEA. Trophic support deprivation downregulated Akt activity, and cannabinoids recovered phospho-Akt levels. Inhibition of PI3K abrogated the survival action and the recovery of Akt activity in response to cannabinoids. SR141716A prevented only the protection conferred by ACEA. Nevertheless, SR141716A and the selective CB2 receptor antagonist SR144528 in combination inhibited the prosurvival action of HU210, which is in accordance with the finding of CB2 receptor expression by oligodendroglial cells. These data identify oligodendrocytes as potential targets of cannabinoid action in the CNS.
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PMID:Cannabinoids promote oligodendrocyte progenitor survival: involvement of cannabinoid receptors and phosphatidylinositol-3 kinase/Akt signaling. 1242 29

(1) We examined A3 adenosine and CB1 cannabinoid receptor-coupled signaling pathways regulating Cl(-) current in a human nonpigmented ciliary epithelial (NPCE) cell line. (2) Whole-cell patch-clamp recordings demonstrated that the A3 receptor agonist, IB-MECA, activates an outwardly rectifying Cl(-)current (I(Cl,Aden)) in NPCE cells, which was inhibited by the adenosine receptor antagonist, CGS-15943 or by the protein kinase C (PKC) activator, phorbol 12,13 dibutyrate (PDBu). (3) Treatment of NPCE cells with pertussis-toxin (PTX), or transfection with the COOH-terminus of beta-adrenergic receptor kinase (ct-betaARK), inhibited I(Cl,Aden). The phosphatidyl inositol 3-kinase (PI3K) inhibitor, wortmannin, had no effect on I(Cl,Aden); however, the mitogen-activated protein kinase kinase (MEK) inhibitor, PD98059, inhibited I(Cl,Aden). (4) Reverse transcription-polymerase chain reaction experiments and immunocytochemistry confirmed mRNA and protein expression for the CB1 receptor in NPCE cells, and the CB1 receptor agonist, Win 55,212-2, activated a PDBu-sensitive Cl(-) current (I(Cl,Win)). (5) Transfection of NPCE cells with the human CB1 (hCB1) receptor, increased I(Cl,Win), consistent with increased receptor expression, and I(Cl,Win) in hCB1 receptor-transfected cells was decreased after application of a CB1 receptor inverse agonist, SR 141716. (6) Constitutive activity for CB1 receptors was not significant in NPCE cells as transfection with hCB1 receptors did not increase basal Cl(-) current, nor was basal current inhibited by SR 141716. (7) I(Cl,Win) was inhibited by PTX preincubation, by transfection with ct-betaARK and by the MEK inhibitor, PD98059, but unaffected by the PI3K inhibitor, wortmannin. (8) We conclude that both A3 and CB1 receptors activate a PKC-sensitive Cl(-) current in human NPCE cells via a G(i/o)/Gbetagamma signaling pathway, in a manner independent of PI3K but involving MAPK.
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PMID:A3 adenosine and CB1 receptors activate a PKC-sensitive Cl- current in human nonpigmented ciliary epithelial cells via a G beta gamma-coupled MAPK signaling pathway. 1278 7

CB1 cannabinoid receptors (CB1Rs) are involved in protecting the brain from ischemia and related disorders. However, the underlying protective mechanisms are incompletely understood. We investigated the effect of CB1R activation on oxidative injury, which has been implicated in neuronal death after cerebral ischemia and neurodegenerative disorders, in mouse cortical neuron cultures. The CB1R agonist Win 55212-2 [R-(+)-[2,3-dihydro-5-methyl-3-[(morpholinyl)methyl]pyrrolo[1,2,3-de]-1,4-benzoxazin-yl]-(1-naphthalenyl)methanone mesylate] reduced neuronal death, measured by lactate dehydrogenase release, in cultures treated with 50 microM FeCl2, and its protective effect was attenuated by the CB1R antagonist SR141716A [N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-cichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide hydrochloride]. The endocannabinoid anandamide reproduced the effect of Win 55212-2, as did the antioxidant 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox). Neuronal injury was more severe after in vitro or in vivo administration of FeCl2 to CB1R-knockout compared with wild-type mice. Win 55212-2 reduced the formation of reactive oxidative species in cortical neuron cultures treated with FeCl2, consistent with an antioxidant action. Pertussis toxin reduced CB1R-mediated protection, which points to a protective mechanism that involves signaling through G(i/o) proteins. Since CB1R-activated G protein signaling inhibits protein kinase A but activates phosphatidylinositol 3-kinase (PI3K), we tested the involvement of these pathways in CB1R-mediated neuroprotection. Dibutyryl-cyclic adenosine monophosphate (dbcAMP) blocked protection by Win 55212-2, whereas the PI3K inhibitor wortmannin did not, and the effect of dbcAMP was inhibited by the protein kinase A inhibitor H89 [N-[2-((p-bromocinnamyl)amino)ethyl]-5-isoquinolinesulfonamide] (> or =10 nM). CB1R-induced, SR141716A-, pertussis toxin-, and dbcAMP-sensitive protection was also observed for two other oxidative insults, exposure to H2O2 or buthionine sulfoximine. Therefore, receptor-stimulated inhibition of protein kinase A seems to be required for the neuroprotective effect of CB1R activation against oxidative neuronal injury.
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PMID:Involvement of protein kinase A in cannabinoid receptor-mediated protection from oxidative neuronal injury. 1562 18

Cannabinoids protect neurons from excitotoxic injury. We investigated the mechanisms involved by studying N-methyl-D-aspartate (NMDA) toxicity in cultured murine cerebrocortical neurons in vitro and mouse cerebral cortex in vivo. The cannabinoid agonist R(+)-[2,3-dihydro-5-methyl-3-[(morpholinyl)-methyl]pyrrolo[1,2,3-de]-1,4-benzoxazin-yl]-(1-naphthalenyl)-methanone mesylate [R(+)-Win 55212] reduced neuronal death in murine cortical cultures treated with 20 microM NMDA, and its protective effect was attenuated by the CB1 cannabinoid receptor (CB1R) antagonist N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-cichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide hydrochloride (SR141716A). Cultures from CB1R-knockout mice were more sensitive to NMDA toxicity than were cultures from wild-type mice. The in vitro protective effect of R(+)-Win 55212 was reduced by pertussis toxin, consistent with signaling through CB1R-coupled G-proteins. The nitric-oxide synthase (NOS) inhibitors 7-nitroindazole (7-NI) and N-omega-nitro-L-arginine methyl ester also reduced NMDA toxicity. In addition, CB1R and neuronal NOS were coexpressed in cultured cortical neurons, suggesting that cannabinoids might reduce NMDA toxicity by interfering with the generation of NO. NOS activity in cerebral cortex was higher in CB1R-knockouts than in wildtype mice, and 7-NI reduced NMDA lesion size. R(+)-Win 55212 inhibited NO production after NMDA treatment of wild-type cortical neuron cultures, measured with 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate, and this effect was reversed by SR141716A. In contrast, R(+)-Win 55212 failed to inhibit NO production in cultures from CB1R knockouts. Dibutyryl-cAMP blocked the protective effect of R(+)-Win 55212, and this was reversed by the protein kinase A (PKA) inhibitor N-[2-((p-bromocinnamyl)amino)ethyl]-5-isoquinolinesulfonamide (H89). Cannabinoids seem to protect neurons against NMDA toxicity at least in part by activation of CB1R and downstream inhibition of PKA signaling and NO generation.
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PMID:Molecular mechanisms of cannabinoid protection from neuronal excitotoxicity. 1629 67