Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P21554 (cannabinoid receptor)
 3,582 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The present study evaluated the modulatory role of central corticotropin-releasing factor (CRF) systems in the mediation of the effects of acute exposure to the brain cannabinoid receptor agonist HU-210 [3-(1,1-dimethylheptyl)-(-)-11-hydroxy-delta 8-tetrahydrocannabinol] on defensive withdrawal behavior in male rats. The apparatus used for the defensive withdrawal test consisted of a small chamber, set on one side of a one-square meter open field. The actions of the potent CRF antagonist [D-Phe12,Nle21,38,C alpha MeLeu37]CRF (D-Phe CRF12-41) were examined on defensive behavior under both novel and familiar conditions. The acute i.c.v. administration of D-Phe CRF12-41 (0.2-5 micrograms/injection) antagonized the defensive behavior response to stressing conditions such as novelty or swim stress in field-habituated animals. The acute i.p. administration of HU-210 (4, 20 and 100 micrograms/kg) produced a clear dose-dependent stress-like effects in field-habituated animals, as reflected in the HU-210-induced increase in both the emergence latency and the mean time spent in the small chamber. The i.c.v. administration of 5 micrograms of D-Phe CRF12-41, 5 min before the administration of the cannabinoid prevented the stressing actions of HU-210 (20 micrograms/kg, but not 100 micrograms/kg). Acute administration of HU-210 also induced a dose-dependent increase in plasma corticosterone levels which was not antagonized by pretreatment with 5 micrograms of D-Phe CRF12-41. The present study suggests a role of central CRF systems in the mediation of the anxiogenic effects of brain cannabinoid receptor agonists. This finding is consistent with a direct hypothalamic effect of cannabinoids on the activation of the pituitary-adrenal axis.
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PMID:Corticotropin-releasing factor (CRF) antagonist [D-Phe12,Nle21,38,C alpha MeLeu37]CRF attenuates the acute actions of the highly potent cannabinoid receptor agonist HU-210 on defensive-withdrawal behavior in rats. 855 57

The agonist-stimulated guanosine 5'-(gamma-[(35)S]thio)triphosphate binding assay was used to anatomically localize receptor-activated G-proteins by autoradiography in post mortem human brain. The optimal conditions for guanosine 5'-(gamma-[(35)S]thio)triphosphate binding to human brain sections were established in post mortem samples of the prefrontal cortex, hippocampus, basal ganglia, brainstem and cerebellar cortex. An excess of GDP (2mM) was required to decrease basal activity and obtain effective stimulation by specific agonists. guanosine 5'-(gamma-[(35)S]Thio)triphosphate binding was increased after stimulation with specific agonists of different G-protein-coupled receptors. They include cannabinoid (WIN55212-2), mu-opioid ([D-Ala(2),N-Me-Phe(4), Gly(5)-ol]enkephalin), serotonin-1A [(+/-)-8-hydroxy-2-(di-n-propylamino)tetralin] and serotonin-1B/1D (sumatriptan), cholinergic muscarinic receptors (carbachol) and alpha(2)-adrenoceptors (UK14304). Such stimulation reached 1458%, 440%, 188%, 219%, 61% and 339%, respectively, over the basal levels. In tissue sections, the use of the above-mentioned agonists (10(-4)M) showed patterns of anatomical distribution similar to those already described by receptor autoradiography, with high densities over the hippocampus (serotonin-1A receptors), cortex (alpha(2)-adrenoceptors) and striatum (mu-opioid receptors). The highest binding levels were reached with the cannabinoid receptor agonist in most of the analysed brain regions. Carbachol produced only moderate stimulation of those same regions. The blockage of agonist-stimulated guanosine 5'-(gamma-[(35)S]thio)triphosphate binding by selective antagonists verified that the effect was receptor mediated. This technique provides a method to identify modifications of the receptor-mediated activation of G-proteins in post mortem human brain with anatomical resolution. It also provides valuable information on the level of drug efficacy in the human species.
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PMID:Autoradiography of receptor-activated G-proteins in post mortem human brain. 1068 21

Previous mutation and modeling studies have identified an aromatic cluster in the transmembrane helix (TMH) 3-4-5 region as important for ligand binding at the CB(1) and CB(2) cannabinoid receptors. Through novel mixed mode Monte Carlo/Stochastic Dynamics (MC/SD) calculations, we tested the importance of aromaticity at position 5.39(275) in CB(1). MC/SD calculations were performed on wild-type (WT) CB(1) and two mutants, Y5.39(275)F and Y5.39(275)I. Results indicated that while the CB(1) Y5.39(275)F mutant is very similar to WT, the Y5.39(275)I mutant shows pronounced topology changes in the TMH 3-4-5 region. Site-directed mutagenesis studies of tyrosine 5.39 to phenylalanine (Y-->F) or isoleucine (Y-->I) in both CB(1) and CB(2) were performed to determine the functional role of this amino acid in each receptor subtype. HEK 293 cells transfected with mutant receptor cDNAs were evaluated in radioligand binding and cyclic AMP assays. The CB(1) mutant and WT receptors were also co-expressed with G-protein-coupled inwardly rectifying channels (GIRK1 and GIRK4) in Xenopus oocytes to assess functional coupling. The Y-->F mutation resulted in cannnabinoid receptors with subtle differences in WT binding and signal transduction. In contrast, the Y-->I mutations produced receptors that could not produce signal transduction or bind to multiple cannabinoid compounds. However, immunofluorescence data indicate that the Y-->I mutation was compartmentalized and expressed at a level similar to that of the WT cannabinoid receptor. These results underscore the importance of aromaticity at position CB(1) 5.39(275) and CB(2) 5.39(191) for ligand recognition in the cannabinoid receptors.
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PMID:A critical role for a tyrosine residue in the cannabinoid receptors for ligand recognition. 1211 Mar 71

Opioids and cannabinoids are both associated with analgetic, psychotropic, and immunomodulatory effects. It has been suggested that both systems interact on multiple levels. We hypothesized that cannabinoids induce opioid receptors and investigated cannabinoid-dependent expression of the mu-opioid receptor subtype in a human T cell model. We report that activation of the peripheral cannabinoid receptor type 2 leads to a de novo induction of mu-opioid receptor transcription in Jurkat E6.1 cells. We show that interleukin-4 is transcriptionally induced in response to cannabinoids and that an interleukin-4 receptor antagonist blocks cannabinoid-dependent induction of mu-opioid receptors, indicating that induced expression of interleukin-4 is required in this process. Induction of interleukin-4 is blocked by decoy oligonucleotides directed against STAT5, indicating the requirement of this transcription factor. In addition, we show cannabinoid-dependent phosphorylation of STAT5. Further experiments demonstrate that interleukin-4 then induces phosphorylation of STAT6, which directly transactivates the mu-opioid receptor gene. In addition, STAT6 induces expression of the transcription factor GATA3, which also contributes to mu-opioid receptor gene transcription. The responsive promoter region of the human mu-opioid receptor gene with the binding sites for both factors was mapped to nt -1001 to -950. To demonstrate functional mu-opioid receptor proteins, morphine-mediated phosphorylation of mitogen-activated protein kinase was investigated. We show that phosphorylation of mitogen-activated protein kinase occurs only in cannabinoid-prestimulated Jurkat E6.1 cells and that it is blocked by the mu-opioid receptor antagonist D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2. In summary, these findings provide a first example for cannabinoid-opioid-interactions in cells of the immune system.
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PMID:Cannabinoid receptor type 2 agonists induce transcription of the mu-opioid receptor gene in Jurkat T cells. 1643 16

The possible role of the peripheral cannabinoid receptor (CB2) in neutrophil migration was investigated by using human promyelocytic HL60 cells differentiated into neutrophil-like cells and human neutrophils isolated from whole blood. Cell surface expression of CB2 on HL60 cells, on neutrophil-like HL60 cells, and on human neutrophils was confirmed by flow cytometry. Upon stimulation with either of the CB2 ligands JWH015 and 2-arachidonoylglycerol (2-AG), neutrophil-like HL60 cells rapidly extended and retracted one or more pseudopods containing F-actin in different directions instead of developing front/rear polarity typically exhibited by migrating leukocytes. Activity of the Rho-GTPase RhoA decreased in response to CB2 stimulation, whereas Rac1, Rac2, and Cdc42 activity increased. Moreover, treatment of cells with RhoA-dependent protein kinase (p160-ROCK) inhibitor Y27632 yielded cytoskeletal organization similar to that of CB2-stimulated cells. In human neutrophils, neither JWH015 nor 2-AG induced motility or morphologic alterations. However, pretreatment of neutrophils with these ligands disrupted N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP)-induced front/rear polarization and migration and also substantially suppressed fMLP-induced RhoA activity. These results suggest that CB2 might play a role in regulating excessive inflammatory response by controlling RhoA activation, thereby suppressing neutrophil migration.
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PMID:Effects of peripheral cannabinoid receptor ligands on motility and polarization in neutrophil-like HL60 cells and human neutrophils. 1651 51

The intracellular C-terminal helix 8 (H8) of the CB(1) cannabinoid receptor deviates from the highly conserved NPXXY(X)(5,6)F G-protein-coupled receptor motif, possessing a Leu instead of a Phe. We compared the signal transduction capabilities of CB(1) with those of an L7.60F mutation and an L7.60I mutation that mimics the CB(2) sequence. The two mutant receptors differed from wild type (WT) in their ability to regulate G-proteins in the [(35)S]guanosine 5'-3-O-(thio)triphosphate binding assay. The L7.60F receptor exhibited attenuated stimulation by agonists WIN-55,212-2 and CP-55,940 but not HU-210, whereas the L7.60I receptor exhibited impaired stimulation by all agonists tested as well as by the inverse agonist rimonabant. The mutants internalized more rapidly than WT receptors but could equally sequester G-proteins from the somatostatin receptor. Both the time course and maximal N-type Ca(2+) current inhibition by WIN-55,212-2 were reduced in the mutants. Reconstitution experiments with pertussis toxin-insensitive G-proteins revealed loss of coupling to Galpha(i3) but not Galpha(0A) in the L7.60I mutant, whereas the reduction in the time course for the L7.60F mutant was governed by Galpha(i3). Furthermore, Galpha(i3) but not Galpha(0A) enhanced basal facilitation ratio, suggesting that Galpha(i3) is responsible for CB(1) tonic activity. Co-immunoprecipitation studies revealed that both mutant receptors were associated with Galpha(i1) or Galpha(i2) but not with Galpha(i3). Molecular dynamics simulations of WT CB(1) receptor and each mutant in a 1-palmitoyl-2-oleoylphosphatidylcholine bilayer suggested that the packing of H8 is different in each. The hydrogen bonding patterns along the helix backbones of each H8 also are different, as are the geometries of the elbow region of H8 (R7.56(400)-K7.58(402)). This study demonstrates that the evolutionary modification to NPXXY(X)(5,6)L contributes to maximal activity of the CB(1) receptor and provides a molecular basis for the differential coupling observed with chemically different agonists.
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PMID:Helix 8 Leu in the CB1 cannabinoid receptor contributes to selective signal transduction mechanisms. 1759 61

Two subtypes of the mammalian cannabinoid receptor have been identified and successfully cloned since 1990. The CB(1) receptor is primarily located in the central nervous system and the CB(2) receptor is almost exclusively expressed in cells of the immune system. The CB(1) and CB(2) receptors are both G-protein coupled receptors and are involved in the inhibition of adenylate cyclase. The CB(2) receptor is of particular importance due to its involvement in signal transduction in the immune system, making it a potential target for therapeutic immune intervention. A number of these selective ligands are derivatives of traditional dibenzopyran based cannabinoids. These include the very recently synthesized (2'R)-1-methoxy-3-(2'-methylbutyl)- Delta (8)-THC (JWH-359) which has a 224 fold selectivity for the CB(2) receptor, readily comparable to the well known 1-deoxy-3-(1',1'-dimethylbutyl)- Delta (8)-THC (JWH-133) which has 200 fold selectivity for the CB(2) receptor. Several 9-hydroxyhexahydrocannabinols have also been synthesized and are found to be selective high affinity ligands for the CB(2) receptor. These are 1-deoxy-9beta-hydroxy-dimethylhexylhexahydrocannabinol (JWH-361, K(i) = 2.7 nM) and 1-deoxy-9beta-hydroxy-dimethylpentylhexahydrocannabinol (JWH-300, K(i) = 5.3 nM). CB(2) selective cannabi-mimetic indoles include 1-(2,3-dichlorobenzoyl)-2-methyl-3-(2-[1-morpholine]ethyl)-5-methoxyindole (L768242), (R)-3-(2-Iodo-5-nitrobenzoyl)-1-(1-methyl-2-piperidinylmethyl)-1H-indole (AM1241) and 1-propyl-2-methyl-3-(1-naphthoyl) indole (JWH-015), which exhibit significant selectivity for the CB(2) receptor coupled with weak affinity for the CB(1) receptor. Bristol-Meyer Squibb has produced a phenylalanine derived cannabimimetic indole which possesses high CB(2) affinity (K(i) = 8 nM) and very low affinity for the CB(1) receptor (K(i) = 4000 nM). This review will discuss the current advances and recent results in the structure-activity relationships (SAR) of selective ligands for the cannabinoid CB(2) receptor.
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PMID:Recent advances in the development of selective ligands for the cannabinoid CB(2) receptor. 1828 88

The CB(1) cannabinoid receptor antagonist N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide hydrochloride (SR141716) has been shown by many investigators to inhibit basal G-protein activity, i.e., to display inverse agonism at high concentrations. However, it is not clear whether this effect is cannabinoid CB(1) receptor-mediated. Using the ligand-stimulated [(35)S]guanosine 5'-3-O-(thio)triphosphate (GTPgammaS) assay, we have found that 10 microM SR141716 slightly but significantly decreases the basal [(35)S]GTPgammaS binding in membranes of the wild-type and CB(1) receptor knockout mouse cortex, parental Chinese hamster ovary (CHO) cells, and CHO cells stably transfected with micro-opioid receptors, MOR-CHO. Accordingly, we conclude that the inverse agonism of SR141716 is CB(1) receptor-independent. Although the specific MOR agonist Tyr-D-Ala-Gly-(NMe)Phe-Gly-ol (DAMGO) saturably and concentration-dependently stimulated [(35)S]GTPgammaS binding, SR141716 (10 microM) inhibited the basal by 25% and competitively inhibited DAMGO stimulation in the mouse cortex. In MOR-CHO membranes, DAMGO caused a 501 +/- 29% stimulation of the basal activity, which was inhibited to 456 +/- 22% by 10 microM SR141716. The inverse agonism of SR141716 was abolished, and DAMGO alone displayed weak, naloxone-insensitive stimulation, whereas the combination of DAMGO and SR141716 (10 microM each) resulted in a 169 +/- 22% stimulation of the basal activity (that was completely inhibited by the prototypic opioid antagonist naloxone) because of pertussis toxin (PTX) treatment to uncouple MORs from G(i)/G(o) proteins. SR141716 proved to bind directly to MORs with low affinity (IC(50) = 5.7 microM). These results suggest the emergence of novel, PTX-insensitive G-protein signaling that is blocked by naloxone when MORs are activated by the combination of DAMGO and SR141716.
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PMID:CB1 receptor-independent actions of SR141716 on G-protein signaling: coapplication with the mu-opioid agonist Tyr-D-Ala-Gly-(NMe)Phe-Gly-ol unmasks novel, pertussis toxin-insensitive opioid signaling in mu-opioid receptor-Chinese hamster ovary cells. 1944 42

Desensitization of the micro-opioid receptor (MOR) has been implicated as an important regulatory process in the development of tolerance to opiates. Monitoring the release of intracellular Ca(2+) ([Ca(2+)](i)), we reported that [D-Ala(2), N-Me-Phe(4), Gly(5)-ol]-enkephalin (DAMGO)-induced receptor desensitization requires receptor phosphorylation and recruitment of beta-arrestins (betaArrs), while morphine-induced receptor desensitization does not. In current studies, we established that morphine-induced MOR desensitization is protein kinase C (PKC)-dependent. By using RNA interference techniques and subtype specific inhibitors, PKCepsilon was shown to be the PKC subtype activated by morphine and the subtype responsible for morphine-induced desensitization. In contrast, DAMGO did not increase PKCepsilon activity and DAMGO-induced MOR desensitization was not affected by modulating PKCepsilon activity. Among the various proteins within the receptor signaling complex, Galphai2 was phosphorylated by morphine-activated PKCepsilon. Moreover, mutating three putative PKC phosphorylation sites, Ser(44), Ser(144) and Ser(302) on Galphai2 to Ala attenuated morphine-induced, but not DAMGO-induced desensitization. In addition, pretreatment with morphine desensitized cannabinoid receptor CB1 agonist WIN 55212-2-induced [Ca(2+)](i) release, and this desensitization could be reversed by pretreating the cells with PKCepsilon inhibitor or overexpressing Galphai2 with the putative PKC phosphorylation sites mutated. Thus, depending on the agonist, activation of MOR could lead to heterologous desensitization and probable crosstalk between MOR and other Galphai-coupled receptors, such as the CB1.
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PMID:Agonist-dependent mu-opioid receptor signaling can lead to heterologous desensitization. 2004 90

Hemopressin is a short, nine amino acid peptide (H-Pro-Val-Asn-Phe-Lys-Leu-Leu-Ser-His-OH) isolated from rat brain that behaves as an inverse agonist at the cannabinoid receptor CB(1), and is shown here to inhibit agonist-induced receptor internalization in a heterologous cell model. Since this peptide occurs naturally in the rodent brain, we determined its effect on appetite, an established central target of cannabinoid signaling. Hemopressin dose-dependently decreases night-time food intake in normal male rats and mice, as well as in obese ob/ob male mice, when administered centrally or systemically, without causing any obvious adverse side effects. The normal, behavioral satiety sequence is maintained in male mice fasted overnight, though refeeding is attenuated. The anorectic effect is absent in CB(1) receptor null mutant male mice, and hemopressin can block CB(1) agonist-induced hyperphagia in male rats, providing strong evidence for antagonism of the CB(1) receptor in vivo. We speculate that hemopressin may act as an endogenous functional antagonist at CB(1) receptors and modulate the activity of appetite pathways in the brain.
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PMID:The peptide hemopressin acts through CB1 cannabinoid receptors to reduce food intake in rats and mice. 2050 4


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