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Z Vogel

Publications and source records attributed to Z Vogel.

At least 55 records · Page 3Linked to original sources
PubMed1996

Endogenous cannabinoid ligands--chemical and biological studies.

Arachidonic acid ethanolamide (anandamide) is a brain constituent that binds to the brain cannabinoid receptor (CB1). It produces many of the pharmacological effects caused by delta 9-tetrahydrocannabinol (delta 9-THC) in mice. Anandamide parallels delta 9-THC in its specific interaction with the cannabinoid receptor and in inhibition of adenylate cyclase. Two additional fatty acid ethanolamides that bind to the cannabinoid receptor, homo-gamma-linolenylethanolamide and docostetraenylethanolamide, have been identified in the brain. We believe that the anandamides are involved in the coordination of movement and short term memory. Depression of ambulation in an open field and the analgetic response to anandamide are not fully developed until adulthood, possibly due to an age-related increase in the CB1 receptor concentration. This observation has clinical implications in pediatrics. A second cannabinoid receptor (CB2) is present in the spleen. A monoglyceride, 2-arachidonyl-glycerol which binds to both CB1 and CB2 in transfected cells and inhibits andenylate cyclase in spleen cells was found in the gut. Its role is apparently associated with the immune system. These fatty acids amides and esters represent a new family of chemical modulators in the body.

Animals↗
PubMed1996

Buprenorphine differentially alters opioid receptor adaptation in rat brain regions.

Previous in vivo studies revealed that the mixed agonist-antagonist buprenorphine can down-regulate mu and up-regulate delta 2 and kappa 1 opioid receptors in rat brain. In this report brain regional differences in opioid receptor adaptation were addressed. Rats received i.p. injections with buprenorphine (0.5-2.5 mg/kg) and were killed 20 h later. Membranes from 7 brain regions were analyzed for mu (3H-[D-Ala2,N-mephe4,Gly-ol5] enkephalin), kappa 1 (3H-U-69593), delta 1 (3H-[D-Pen2, D-Pen5] enkephalin) and delta 2 (3H-deltorphin II) receptor binding parameters. Buprenorphine induced down-regulation of mu receptors in frontal cortex, occipital cortex, thalamus, hippocampus, striatum and brain stem. Kd values for 3H-[D-Ala2,N-mephe4,Gly-ol5] enkephalin were unchanged from controls. Up-regulation of kappa 1 receptors was observed in frontal, parietal, occipital cortexes and striatum. Binding to delta 2 sites was elevated in frontal and parietal cortexes. Buprenorphine did not alter delta 1 binding in any of the regions examined. Changes in opioid receptor adaptation induced by buprenorphine were further supported by data from cross-linking of 125I-beta-endorphin to cortical membrane preparations. A reduction in a 60- to 65-kDa band was detected in frontal and occipital cortices in which binding assays revealed down-regulation of mu receptors. In parietal cortex neither the 60- to 65-kDa product nor Bmax changes were observed. These results indicate that buprenorphine is a useful tool to study brain opioid receptor adaptation in vivo and the information accrued may be relevant to the mode of action of this drug in the treatment of heroin and cocaine abuse.

Adaptation, Physiological↗
PubMed1995

Increased expression of synapsin I mRNA in defined areas of the rat central nervous system following chronic morphine treatment.

Chronic opiate administration leads to a selective regulation of several cellular proteins and mRNAs. This phenomenon has been viewed as a compensatory mechanism to the opiate signaling leading to the development of opiate addiction. In this study, in situ hybridization histochemistry experiments were employed to investigate the effect of chronic morphine treatment on synapsin I gene expression. We show here for the first time that prolonged morphine exposure causes a selective increase in the mRNA levels of synapsin I in several brain regions which are considered to be important for opiate action. Quantitative analysis of the signals, obtained by hybridization of digoxigenin-labeled antisense RNA probe, revealed a 5.8- and 7-fold increase of synapsin I mRNA levels in the locus coeruleus and the amygdala of morphine-treated rats, respectively, as compared with control untreated rats. Increased expression of synapsin I mRNA was also observed in the spinal cord of morphine-treated rats (by 3.8-fold). Since opiates were shown to attenuate neurotransmitter release and reduce synapsin I phosphorylation, it is suggested that the increase in synapsin I levels would lead to the requirement of higher amounts of opiate agonists to obtain the opiate physiological effects. These results suggest that the increases in mRNA levels of synapsin I in these specific areas can be part of the molecular mechanism(s) underlying opiate tolerance and withdrawal.

Animals↗
PubMed1995

Adenylylcyclase supersensitization in mu-opioid receptor-transfected Chinese hamster ovary cells following chronic opioid treatment.

Using CHO cells stably transfected with rat mu-opioid receptor cDNA, we show that the mu-agonists morphine and [D-Ala2,N-methyl-Phe4,Gly-ol5]enkephalin are negatively coupled to adenylylcyclase and inhibit forskolin-stimulated cAMP accumulation. Chronic exposure of cells to morphine leads to the rapid development of tolerance. Withdrawal of morphine or [D-Ala2,N-methyl-Phe4,Gly-ol5]enkephalin following chronic treatment (by wash or addition of the antagonist naloxone) leads to an immediate increase in cyclase activity (supersensitization or overshoot), which is gradually reversed upon further incubation with naloxone. Phosphodiesterase inhibitors do not affect the overshoot, indicating that it results from cyclase stimulation rather than phosphodiesterase regulation. Morphine's potency to inhibit cAMP accumulation is the same before and after chronic treatment, suggesting that the apparent tolerance results from cyclase activation, rather than from receptor desensitization. The similar kinetics of induction of tolerance and overshoot support this idea. Both the overshoot and acute opioid-induced cyclase inhibition are blocked by naloxone and are pertussis toxin-sensitive, indicating that both phenomena are mediated by the mu-receptor and Gi/G(o) proteins. The supersensitization is cycloheximide-insensitive, indicating that it does not require newly synthesized proteins. This is supported by the rapid development of supersensitization. Taken together, these results show that mu-transfected cells can serve as a model for investigating molecular and cellular mechanisms underlying opiate drug addiction.

1-Methyl-3-isobutylxanthine↗
PubMed1995

Cannabinomimetic behavioral effects of and adenylate cyclase inhibition by two new endogenous anandamides.

We have previously shown that the endogenous putative cannabinoid ligand arachidonylethanolamide (anandamide, 20:4, n - 6) induces in vivo and in vitro effects typical of a cannabinoid agonist. We now report that two other endogenous anandamides, docosatetraenylethanolamide (anandamide, 22:4, n - 6) and homo-gamma-linolenylethanolamide (anandamide, 20:3, n - 6), have similar activities. The new anandamides bind to SV40-transformed African green monkey kidney cells transfected with the rat brain cannabinoid receptor cDNA and display K1 values of 253.4 +/- 41.1 and 244.8 +/- 38.7, respectively. The value found for arachidonylethanolamide was 155.1 +/- 13.8 nM. In addition, the new anandamides inhibit prostaglandin E1-stimulated adenylate cyclase activity in Chinese hamster ovary-K1 cells transfected with the cannabinoid receptor, as well as in N18TG2 mouse neuroblastoma cells that express the cannabinoid receptor naturally. The IC50 values for the inhibition of adenylate cyclase in transfected Chinese hamster ovary-K1 cells were 116.8 +/- 8.7 and 109.3 +/- 8.6 nM for docosatetraenylethanolamide and homo-gamma-linolenylethanolamide, respectively. These values were similar to that obtained with arachidonylethanolamide (100.5 +/- 7.7 nM), but were significantly higher than the IC50 value observed with the plant cannabinoid delta9-tetrahydrocannabinol (9.2 +/- 8.6 nM). The inhibitory effects of the anandamides on adenylate cyclase activity were blocked by pertussis toxin, indicating the involvement of pertussis toxin-sensitive GTP-binding protein(s). In a tetrad of behavioral assays for cannabinoid-like effects, the two new anandamides exerted similar behavioral effects to those observed with delta9-tetrahydrocannabinol and arachidonylethanolamide: inhibition of motor activity in an open field, hypothermia, catalepsy on a ring, and analgesia on a hot plate.

Adenylyl Cyclases↗
PubMed1995

The peripheral cannabinoid receptor: adenylate cyclase inhibition and G protein coupling.

Two cannabinoid receptors, designated neuronal (or CB1) and peripheral (or CB2), have recently been cloned. Activation of CB1 receptors leads to inhibition of adenylate cyclase and N-type voltage-dependent Ca2+ channels. Here we show, using a CB2 transfected Chinese hamster ovary cell line, that this receptor binds a variety of tricyclic cannabinoid ligands as well as the endogenous ligand anandamide. Activation of the CB2 receptor by various tricyclic cannabinoids inhibits adenylate cyclase activity and this inhibition is pertussis toxin sensitive indicating that this receptor is coupled to the Gi/G(o) GTP-binding proteins. Interestingly, contrary to results with CB1, anandamide did not inhibit the CB2 coupled adenylate cyclase activity and delta 9-tetrahydrocannabinol had only marginal effects. These results characterize the CB2 receptor as a functional and distinctive member of the cannabinoid receptor family.

Adenylate Cyclase Toxin↗
PubMed1995

Inotropic action of sigma receptor ligands in isolated cardiac myocytes from adult rats.

High affinity binding sites for sigma receptor ligands were found in membranes of cardiac myocytes from adult rats. The sigma receptor ligand (+)-3-hydroxyphenyl-N-(1-propyl)piperidine ((+)-3-PPP) binds with a Kd of 17.9 +/- 4.0 nM and a Bmax of 275 +/- 32.1 fmol/mg protein. Competition experiments of (+)-pentazocine with [3H]1,3-di-O-tolylguanidine ([3H]DTG) binding yielded a Ki of 6.1 +/- 1.3 nM. The majority of the sites (> 80%) were of the sigma 1 subtype. Exposure of isolated cardiomyocytes from adult rats to (+)-3-PPP (10 nM-1.0 microM) caused a marked concentration-dependent increase in the amplitude of systolic cell contraction, reaching 149% of control level, with an apparent ED50 value of 4.5 nM. The increase in the contraction amplitude was markedly inhibited by pretreatment with verapamil or thapsigargin. An increase in the amplitude of [Ca2+]i transients, similar to that in the amplitude of cell contraction, was observed in indo-1-loaded cardiomyocytes exposed to 0.1 microM (+)-3-PPP. Exposure to 10 nM of haloperidol or (+)-pentazocine induced an increase in the amplitude of contraction, reaching 188% and 138% (respectively) of control level. A lower concentration of haloperidol or (+)-pentazocine (1 nM) did not induce an increase in the contraction amplitude but rather reduced the amplitude to 70-80% of control.

Animals↗
PubMed1995

kappa-Opioid receptor-transfected cell lines: modulation of adenylyl cyclase activity following acute and chronic opioid treatments.

The opioid receptors mu, delta and kappa have recently been cloned. Here we show that kappa-agonists inhibit adenylyl cyclase activity in Chinese hamster ovary cells stably transfected with rat kappa-opioid receptor cDNA. Chronic exposure of the cells to kappa-agonists did not lead to significant desensitization of the capacity of the agonists to inhibit adenylyl cyclase. On the other hand, withdrawal of the agonist following the chronic treatment led to the phenomenon of supersensitivity ('overshoot') of adenylyl cyclase activity. Both the inhibition of adenylyl cyclase activity by the acute opioid treatment and the chronic agonist-induced supersensitivity are pertussis toxin sensitive, demonstrating involvement of Gi/Go proteins in both processes.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1995

The fourth immunoglobulin domain of the stem cell factor receptor couples ligand binding to signal transduction.

Receptor dimerization is ubiquitous to the action of all receptor tyrosine kinases, and in the case of dimeric ligands, such as the stem cell factor (SCF), it was attributed to ligand bivalency. However, by using a dimerization-inhibitory monoclonal antibody to the SCF receptor, we confined a putative dimerization site to the nonstandard fourth immunoglobulin-like domain of the receptor. Deletion of this domain not only abolished ligand-induced dimerization and completely inhibited signal transduction, but also provided insights into the mechanism of the coupling of ligand binding to dimer formation. These results identify an intrinsic receptor dimerization site and suggest that similar sites may exist in other receptors.

Animals↗
PubMed1995

Dynorphins modulate DNA synthesis in fetal brain cell aggregates.

Previously, opioid peptide analogues, beta-endorphin, and synthetic opiates were found to inhibit DNA synthesis in 7-day fetal rat brain cell aggregates via kappa- and mu-opioid receptors. Here dynorphins and other endogenous opioid peptides were investigated for their effect on DNA synthesis in rat and guinea pig brain cell aggregates. At 1 microM, all dynorphins tested and beta-endorphin inhibited [3H]thymidine incorporation into DNA by 20-38% in 7-day rat brain cell aggregates. The putative epsilon-antagonist beta-endorphin (1-27) did not prevent the effect of beta-endorphin, suggesting that the epsilon-receptor is not involved in opioid inhibition of DNA synthesis. The kappa-selective antagonist norbinaltorphimine blocked dynorphin A or B inhibition of DNA synthesis, implicating a kappa-opioid receptor. In dose-dependency studies, dynorphin B was three orders of magnitude more potent than dynorphin A in the attenuation of thymidine incorporation, indicative of the mediation of its action by a discrete kappa-receptor subtype. The IC50 value of 0.1 nM estimated for dynorphin B is in the physiological range for dynorphins in developing brain. In guinea pig brain cell aggregates, the kappa-receptor agonists U50488, U69593, and dynorphin B reduced thymidine incorporation by 40%. When 21-day aggregates were treated with dynorphins, a 33-86% enhancement of thymidine incorporation was observed. Because both 7- and 21-day aggregates correspond to stages in development when glial cell proliferation is prevalent and glia preferentially express kappa-receptors in rat brain, these findings support the hypothesis that dynorphins modulate glial DNA synthesis during brain ontogeny.

Animals↗
PubMed1995

Low doses of anandamides inhibit pharmacological effects of delta 9-tetrahydrocannabinol.

It has been shown previously that the endogenous cannabinoid receptor ligand arachidonylethanolamide (anandamide 20:4, n-6) induces in vivo and in vivo effects typical of a cannabinoid partial agonist. We now report that the synthetic docosahexaenylethanolamide (anandamide 22:6, n-3) shows similar activities. In addition we show that these two anandamides, under certain experimental conditions, antagonize the effects of delta 9-THC both in vivo and in vitro. Thus a significant decrease in the potency of delta 9-THC-induced inhibition of adenylate cyclase was observed in N18TG2 neuroblastoma cells that were pretreated with low concentrations of anandamides. At these low concentrations of anandamides had no effect when applied alone. In vivo, Sabra or ICR mice were subjected to a tetrad of tests, designed to detect cannabinoid-induced effects. Mice pretreated (i.p.) with 10 mg/kg of delta 9-THC received injections with anandamides. Only low doses (0.0001-0.1 mg/kg) of the anandamides, which had no effects when administered alone, partially or fully inhibited the THC-induced effects. These findings suggest that the inhibition of delta 9-THC-induced effects by low doses of anandamides may be due to partial agonistic effects of these materials. It is possible that low doses of the anandamides are capable of activating a Gs protein mediated signaling pathway, or may cause an allosteric modulation of the cannabinoid receptor.

Animals↗
PubMed1994

A monoclonal anti-idiotypic antibody to opioid receptors labels desipramine-induced opioid binding sites on rat C6 glioma cells and attenuates thymidine incorporation into DNA.

Treatment of rat C6 glioma cells with the tricyclic antidepressant desipramine induces opioid binding. Here the distribution of these opioid-binding sites on C6 cell membranes and a functional property were investigated. Immunohistochemical examination of C6 cells was performed using a monoclonal anti-idiotypic antibody to opioid receptors (Ab2AOR). Ab2AOR uniformly labeled > 97% of the cells exposed to desipramine over their entire surface. The opioid-receptor antagonist naltrexone completely blocked Ab2AOR binding. Ab2AOR, which has opioid agonist properties, also inhibited DNA synthesis in desipramine-treated but not in naive C6 cells. Similarly, morphine blocked C6 cell proliferation only after desipramine treatment. The antineurotrophic action of Ab2AOR was reversed by naltrexone and was insensitive to pertussis toxin. These findings demonstrate that Ab2AOR suppresses the proliferation of C6 glioma cells by binding to desipramine-induced opioid receptors.

Animals↗
PubMed1994

Opioids inhibit endothelin-mediated DNA synthesis, phosphoinositide turnover, and Ca2+ mobilization in rat C6 glioma cells.

Opioid agonists inhibit DNA synthesis in C6 rat glioma cells that express opioid receptors, induced by desipramine (DMI). This inhibition was not observed in cells that were not treated with DMI, and thus did not express opioid-binding sites. Endothelin, a known mitogen, increased thymidine incorporation dose dependently (up to 1.7-fold) in DMI-treated C6 cells. This increase was reversed by an anti-idiotypic antibody to opioid receptors, Ab2AOR, which has opioid agonist properties. The opioid antagonist naltrexone blocked the inhibition caused by Ab2AOR. Endothelin also stimulated phosphoinositide (PI) turnover and this effect was inhibited by morphine (50%) or by Ab2AOR (72%) in DMI-treated but not in DMI-untreated C6 cells. These actions of morphine and Ab2AOR were reversed by naltrexone. The inhibition of PI turnover and of thymidine incorporation by Ab2AOR or morphine was insensitive to pertussis toxin (PTX). Since PI turnover is known to induce Ca2+ mobilization, it was of interest to examine the effects of the applied opioids on intracellular Ca2+ concentrations. Endothelin increased the concentration of cytosolic free Ca2+ in the cells while Ab2AOR, morphine, and beta-endorphin reversed the endothelin-induced Ca2+ mobilization in DMI-treated but not in DMI-untreated C6 cells. The effect of these agonists was also blocked by naltrexone. The results indicate that glial cells can be a target of an opioid receptor-mediated antimitogenic action and that an abatement in PI turnover and Ca2+ mobilization may be associated with this mechanism.

Animals↗
PubMed1994

Sigma receptor ligands modulate contractility, Ca++ influx and beating rate in cultured cardiac myocytes.

Specific binding of [3H]-1,3-di-o-tolylguanidine (DTG) and (+)-[3H]-(3-hydroxyphenyl)-N-(1-propyl)-piperidine [(+)-3-PPP] to membranes of cultured cardiac myocytes from neonatal rats revealed the presence of sigma receptors on these cells. Exposure of cultured cardiomyocytes to nanomolar concentrations of (+)-3-PPP, (+)-pentazocine and haloperidol induced specific patterns of changes in contractility of electrically paced cultures. The amplitude of systolic cell-motion (ASM) decreased by 10 to 25% 1 to 2 min after drug addition, then transiently increased (3-10 min) and finally decreased to about 75% of control level. Fluorescence measurements on indo-1 loaded cardiomyocytes revealed drug-induced changes in the size of the concentration of free cytosolic calcium ([Ca++]i)-transients, similar to the changes observed in ASM. These changes appear to be mediated by corresponding changes in the rates of 45Ca++ influx which increased 2 to 7 min after the addition of (+)-3-PPP and decrease to 50% of the control level thereafter. Preincubation with thapsigargin, which depletes the sarcoplasmic reticulum-Ca++ stores, did not affect the pattern of changes in ASM, induced by the subsequent addition of (+)-3-PPP. This indicates that the changes in [Ca++]i are not mediated by sarcoplasmic reticulum-Ca++ transport systems. Exposure to sigma ligands did not affect the apparent sensitivity of the myofilaments to Ca++, as indicated by the relationships between changes in ASM and in [Ca++]i-transients. Cultures which were not paced, contracted spontaneously at a constant rhythm. Sigma receptor ligands caused changes in beating frequencies which were followed by irregular contractions.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Modulation of thymidine incorporation by kappa-opioid ligands in rat spinal cord-dorsal root ganglion co-cultures.

beta-Endorphin, met-enkephalin and several mu-selective opioid agonists were shown to decrease thymidine incorporation into DNA in various neural cell cultures. We now report that the kappa-selective opioid agonists U50488, U69593 and MR2034 modulate [3H]thymidine incorporation into DNA in rat spinal cord-dorsal root ganglion co-cultures. U50488 at 10 microM increased by 60% thymidine incorporation in 6-day-old cultures. The thymidine incorporation induced by U50488 was blocked by the kappa-selective antagonist nor-binaltorphimine, as well as by pertussis toxin and LiCl. U50488 treatment stimulated phosphatidylinositol turnover by three-fold compared with untreated controls. These findings suggest that kappa-opioid agonists modulate DNA synthesis in spinal cord-dorsal root ganglion co-cultures through a mechanism which involves pertussis toxin-sensitive GTP-binding proteins, as well as activation of phosphatidylinositol turnover.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1993

Cannabinoids inhibit agonist-stimulated formation of inositol phosphates in rat hippocampal cultures.

The effect of cannabinoids on phosphoinositide metabolism stimulated by activation of muscarinic receptors, alpha 1-adrenoceptors or glutamate receptors was examined in rat hippocampal cultures. Carbachol stimulated phosphoinositide turnover by 5.5-fold over basal level, whereas glutamate and norepinephrine stimulated phosphoinositide turnover by 2-fold. Addition of cannabinoids, such as delta 8-tetrahydrocannabinol, delta 9-tetrahydrocannabinol or the psychoinactive cannabidiol inhibited formation of inositol phosphates evoked by carbachol, glutamate or norepinephrine by 55-90%. The cannabinoids alone only slightly inhibited the basal unstimulated formation of inositol phosphates. The inhibitory effect of the cannabinoids was dose-dependent and was achieved within the range of pharmacologically relevant concentrations. IC50 values for delta 8-tetrahydrocannabinol, delta 9-tetrahydrocannabinol and cannabidiol were 9.6 +/- 1.0, 9.7 +/- 0.3 and 7.9 +/- 0.4 microM, respectively. Pretreatment with pertussis toxin (100 ng/ml, 18 h) did not affect the carbachol-induced stimulation of phosphoinositide turnover or its inhibition by the cannabinoids. This suggests that the inhibition by the cannabinoids of the stimulated formation of inositol phosphates is not mediated through a pertussis toxin-sensitive GTP-binding protein nor through the known effect of the cannabinoids on adenylate cyclase inhibition.

Adenylate Cyclase Toxin↗
PubMed1993

Opiate receptor agonists regulate phosphorylation of synapsin I in cocultures of rat spinal cord and dorsal root ganglion.

Kappa opiate receptor agonists applied to cocultures of spinal cord and dorsal root ganglion neurons have been previously shown to inhibit voltage-dependent Ca2+ influx and adenylate cyclase activity. Here we describe the effect of kappa opiate receptor agonists on phosphorylation of synapsin I, a synaptic-vesicle-associated protein whose phosphorylation was shown to be regulated by cAMP and Ca2+ concentrations. Depolarization of spinal cord-dorsal root ganglion cocultured cells (by high K+ or veratridine) and the addition of forskolin (which activates adenylate cyclase) led to increased phosphorylation of synapsin I. Addition of kappa opiate agonists attenuated both the depolarization- and the forskolin-induced phosphorylation of synapsin I. This attenuation was blocked by the opiate antagonist naloxone. mu and delta opiate receptor agonists had much weaker effects on the depolarization-induced phosphorylation of synapsin I. Similarly, kappa opiate agonists decreased (by 40-60%) the high-K+- or veratridine-induced phosphorylation of synapsin I in spinal cord synaptosomes. These results show that opiate ligands modulate synapsin I phosphorylation. Moreover, the data could explain the reduction in synaptic efficacy observed after opiate treatment.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗