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

We have recently reported that, in SH-SY5Y cells, mu-opioid receptor occupancy activates phospholipase C via a pertussis toxin-sensitive G-protein. In the present study we have further characterized the mechanisms involved in this process. Fentanyl (0.1 microM) caused a monophasic increase in inositol 1,4,5-trisphosphate mass formation, with a peak (20.5 +/- 3.6 pmol/mg of protein) at 15 s. Incubation in Ca(2+)-free buffer abolished this response, while Ca2+ replacement 1 min later restored the stimulation of inositol 1,4,5-trisphosphate formation (20.1 +/- 0.6 pmol/mg of protein). In addition, nifedipine (1 nM-0.1 mM), an L-type Ca(2+)-channel antagonist, caused a dose-dependent inhibition of inositol 1,4,5-trisphosphate formation, with an IC50 of 60.3 +/- 1.1 nM. Elevation of endogenous beta/gamma subunits by selective activation of delta-opioid and alpha 2 adrenoceptors failed to stimulate phospholipase C. Fentanyl also caused a dose-dependent (EC50 of 16.2 +/- 1.0 nM), additive enhancement of carbachol-induced inositol 1,4,5-trisphosphate formation. In summary, we have demonstrated that in SH-SY5Y cells activation of the mu-opioid receptor allows Ca2+ influx to activate phospholipase C. However, the possible role of this mechanism in the process of analgesia remains to be elucidated.
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PMID:Mu-opioids activate phospholipase C in SH-SY5Y human neuroblastoma cells via calcium-channel opening. 783 76

Our overall goal was to investigate the mechanism by which fentanyl attenuates acetylcholine-induced contraction in porcine coronary artery. We tested the hypothesis that fentanyl attenuates muscarinic coronary contraction via sigma receptor activation. Left coronary artery vascular rings were isolated from porcine hearts and were suspended in organ chambers for isometric tension recording. In untreated coronary vascular rings, acetylcholine administration resulted in dose-dependent contraction. Fentanyl attenuated acetylcholine-induced contraction. The sigma ligands--(+)-pentazocine, (+)-cyclazocine, haloperidol, and 1,3-di-o-tolylguanidine--also inhibited acetylcholine-induced contraction. In contrast, the selective sigma ligand, (+)-3-(3-hydroxyphenyl)-N-(1-propyl) piperidine failed to have an inhibitory effect on acetylcholine-induced contraction. Moreover, metaphit (1-[1(3-isothiocyanatophenyl)cyclohexyl]piperidine), which causes irreversible acylation of sigma receptors, only inhibited acetylcholine-induced contraction when it was present in the organ chamber. We also assessed the effects of inhibiting various points in the signal transduction pathway distal to naloxone-sensitive opioid receptor activation on acetylcholine-induced contraction. Selective (glybenclamide) and nonselective (tetraethylammonium) K(+)-channel inhibition, guanosine triphosphate-binding protein inactivation (pertussis toxin), and Type 1 and Type 2 dopamine receptor inhibition all failed to alter the attenuating effect of fentanyl on acetylcholine-induced contraction. Thus, neither sigma or opioid receptor activation is a prerequisite for fentanyl-induced inhibition of muscarinic coronary contraction.
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PMID:Sigma receptor activation does not mediate fentanyl-induced attenuation of muscarinic coronary contraction. 861 Sep 10

1. The rat mu-opioid receptor has recently been cloned yet its second messenger coupling remains unclear. The endogenous mu-opioid receptor in SH-SY5Y cells couples to phospholipase C (PLC), increases [Ca2+]i and inhibits adenylyl cyclase (AC). We have examined the effects of mu-opioid agonists on inositol(1,4,5)trisphosphate (Ins(1,4,5)P3), [Ca2+]i and adenosine 3':5'-cyclic monophosphate (cyclic AMP) formation in Chinese hamster ovarian (CHO) cells transfected with the cloned mu-opioid receptor. 2. Opioid receptor binding was assessed with [3H]-diprenorphine ([3H]-DPN) as a radiolabel. Ins(1,4,5)P3 and cyclic AMP were measured by specific radioreceptor assays. [Ca2+]i was measured fluorimetrically with Fura-2. 3. Scatchard analysis of [3H]-DPN binding revealed that the Bmax varied between passages. Fentanyl (10 pM 1 microM) dose-dependently displaced [3H]-DPN, yielding a curve which had a Hill slope of less than unity (0.6 +/- 0.1), and was best fit to a two site model, with pK1 values (% of sites) of 9.97 +/- 0.4 (27 +/- 4.8%) and 7.68 +/- 0.07 (73 +/- 4.8%). In the presence of GppNHp (100 microM) and Na+ (100 mM), the curve was shifted to the right and became steeper (Hill slope = 0.9 +/- 0.1) with a pK1 value of 6.76 +/- 0.04. 4. Fentanyl (0.1 nM-1 microM) had no effect on basal, but dose-dependently inhibited forskolin (1 microM)-stimulated, cyclic AMP formation (pIC50 -7.42 +/- 0.23), in a pertussis toxin (PTX; 100 ng ml-1 for 24 h)-sensitive and naloxone-reversible manner (K1 = 1.7 nM). Morphine (1 microM) and [D-Ala2, MePhe4, gly(ol)5]-enkephalin (DAMGO, 1 microM) also inhibited forskolin (1 microM)-stimulated cyclic AMP formation, whilst [D-Pen2, D-Pen5], enkephalin (DPDPE, 1 microM) did not. 5. Fentanyl (0.1 nM-10 microM) caused a naloxone (1 microM)-reversible, dose-dependent stimulation of Ins(1,4,5)P3 formation, with a pEC50 of 7.95 +/- 0.15 (n-5), PTX (100 ng ml-1 for 24 h) abolished, whilst Ni2 (2.5 mM) inhibited (by 52%), the fentanyl-induced Ins(1,4,5)P3 response. Morphine (1 microM) and DAMGO (1 microM), but not DPDPE (1 microM), also stimulated Ins(1,4,5)P3 formation. Fentanyl (1 microM) also caused an increase in [Ca2+]i (80 +/- 16.4 nM, n-6), reaching a maximum at 26.8 +/- 2.5 s. The increase in [Ca2+]i remained elevated until sampling ended (200 s) and was essentially abolished by the addition of naloxone (1 microM). Pre-incubation with naloxone (1 microM, 3 min) completely abolished fentanyl-induced increases in [Ca2+]i. 6. In conclusion, the cloned mu-opioid receptor when expressed in CHO cells stimulates PLC and inhibits AC, both effects being mediated by a PTX-sensitive G-protein. In addition, the receptor couples to an increase in [Ca2+]i. These findings are consistent with the previously described effector-second messenger coupling of the endogenous mu-opioid receptor.
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PMID:The effects of recombinant rat mu-opioid receptor activation in CHO cells on phospholipase C, [Ca2+]i and adenylyl cyclase. 913 31

The alpha-2 adrenergic agonist dexmedetomidine (Dex), 3-300 microg/kg, i.p., decreased cerebellar cGMP in a dose-dependent manner. Fentanyl (F), an opioid agonist, increased cerebellar cGMP at 0.3 mg/kg, s.c., and decreased it at doses >/=1 mg/kg. The inhibitory effect was receptor specific, that of Dex being blocked by the alpha-2 adrenergic antagonist yohimbine, 5 mg/kg, i.p.; that of F by the opioid antagonist naloxone, 5 mg/kg, i.p. In contrast the stimulatory effect of F was blocked by both naloxone and yohimbine. Yohimbine also enhanced the inhibitory effect of F. In mice pretreated with pertussis toxin, 2 microgram/mouse, given i.c.v. 72 h before the agonists, the decrease in cGMP induced by Dex or F was not affected, while the stimulatory effect of F was reversed to an inhibitory effect. When inhibiting doses of F and Dex were administered together, the cGMP response was smaller than the sum of the individual responses. Dex attenuated in a dose-dependent manner the decrease in cGMP induced by F, and unmasked or enhanced the stimulatory effect of F. These results show that the alpha-2 adrenergic- and opioid-receptors are coupled to the cGMP effector system and suggest that the two pathways converge at a common post-receptor site in the cascade of events transducing the receptor signal to cGMP regulation.
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PMID:Interaction of the alpha-2 adrenergic- and opioid receptor with the cGMP system in the mouse cerebellum. 982 60

In this study, we explored the relationship between regulation of surface mu-opioid receptor number, ligand-induced G protein activation (measured by [(35)]S]guanosine-5'-O-(3-thio)triphosphate (GTPgammaS) binding) and second messenger signaling (measured by the inhibition of cAMP accumulation). Etorphine and two isomers of cis-beta-hydroxy-3-methylfentanyl (RTI-1a and RTI-1b), which were full agonists for G protein activation and signaling, caused approximately a 50% loss of surface receptors after 1 h of treatment. Fentanyl and morphine were full agonists for inhibiting cAMP accumulation and partial agonists for stimulating [(35)S]GTPgammaS binding and internalization. Although both agonists were approximately 80% as efficacious as etorphine in stimulating [(35)S]GTPgammaS binding, fentanyl induced a 35% loss of surface receptors, whereas morphine only caused a 10% loss. Additionally, both long- and short-term treatment with the opioid antagonist naloxone caused increases in surface receptors. Unexpectedly, the weak partial agonists buprenorphine and one isomer of cis-beta-hydroxy-3-methylfentanyl (RTI-1d) also were found to cause an increase in surface receptors. Treatment with pertussis toxin (PTX) diminished agonist-induced loss of surface receptors. Furthermore, the abilities of morphine and fentanyl to cause internalization were more impaired after PTX treatment than that of etorphine. PTX treatment also significantly enhanced the increase in surface receptor number caused by 18-h treatment with naloxone and buprenorphine. The results of this study suggest that disruption of G protein coupling by PTX treatment affects ligand-regulated mu-receptor trafficking and that partial agonists for signaling can vary greatly in the ability to regulate the number of surface mu-opioid receptors.
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PMID:Ligand-induced changes in surface mu-opioid receptor number: relationship to G protein activation? 1068 32

In this study, we explored the relationship between ligand-induced regulation of surface delta opioid receptors and G protein activation. G protein activation was assessed with [(35)S]guanosine-5'-O-(3-thio)triphosphate (GTP gamma S) binding assays conducted at both 37 and 0 degrees C. Ligand-independent (constitutive) activity of the delta-receptor was readily observed when the [(35)S]GTP gamma S binding assay was performed at 37 degrees C. We identified a new class of alkaloid inverse agonists (RTI-5989-1, RTI-5989-23, RTI-5989-25), which are more potent than the previously described peptide inverse agonist ICI-174864 (N,N-diallyl-Tyr-Aib-Aib-Phe-Leu). Treatment with these inverse agonists for 18 h caused up-regulation of surface receptors. Eighteen-hour treatment with etorphine resulted in approximately 90% loss of surface receptor, whereas fentanyl, diprenorphine, and morphine caused between 20 and 50% loss. The abilities of ligands to modulate [(35)S]GTP gamma S binding at 37 degrees C showed a strong correlation with their abilities to regulate surface receptor number (r(2) = 0.86). Interestingly, the ability of fentanyl to activate G proteins was markedly temperature sensitive. Fentanyl showed no stimulation of [(35)S]GTP gamma S binding at 0 degrees C but was as efficacious as etorphine, morphine, and diprenorphine at 37 degrees C. Neither the ligand-induced receptor increases nor decreases were perturbed by pertussis toxin pretreatment, suggesting that functional G proteins are not required for ligand-regulated delta-opioid receptor trafficking.
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PMID:Agonist-, antagonist-, and inverse agonist-regulated trafficking of the delta-opioid receptor correlates with, but does not require, G protein activation. 1150 98